SURVEY OF SUPPORT SOFTWARE
FOR RELIABILITY ENGINEERING
By Reid Willis
Washington Chapter, Society of Reliability Engineers
April 1, 2006
This report is a survey of reliability support software tools that are distributed in the U.S.
by vendors who offer a variety of reliability programs that can share common target
system data.
Any errors or omissions are the sole responsibility of the author, who requests comments
by readers. Contact him by e-mail at reidwillis@juno.com.
SURVEY OF SUPPORT SOFTWARE
FOR RELIABILITY ENGINEERING
April 1, 2006
Normally we think of computer support as a great labor and time saver. R&M
software tools can guide data acquisition, respond quickly to system changes, provide
mathematical support, and help prepare presentation of the results. But nothing is ever
that easy. When selecting computer tools for the support of reliability analyses, the user
should carefully consider several important factors including the R&M standards
employed, data sharing, special capabilities and features, user friendliness, vendor
support, and cost.
Adherence to a given standard is one of the most popular features of support
software–––and one of the most annoying. The user is on safe ground if the software
strictly enforces conformance to the chosen procedure. However, if the user wants to
incorporate a variation that is not in the rules, the tool’s program may not allow it.
Commonality of user project data is a strong argument in favor of choosing a suite of
tools from the same vendor. This means that the user can establish a project data base for
the target system that supports and coordinates all ongoing reliability analyses for that
project.
Computer tools from different vendors that support a particular task may offer a wide
variety of special features. The features deserve a close look, because they strongly
affect the most significant cost of a reliability analysis task: the professional hours
involved. The vendor directory and program summaries below are intended to suggest
which tools might meet a user’s needs, and how to locate the vendor for further
information.
It can be said that a buyer will never get his money’s worth out of a tool if he and his
engineers don’t like it because it is difficult for them to learn or awkward to operate. The
vendors normally provide free demonstration versions of their software. When it comes
down to final selection among competing programs that seem to have the desired
capabilities, it is a worthwhile investment to obtain demos and try them out.
This is also an opportunity to test the vendor’s support. The initial use of any
scientific software is bound to be a frustrating experience because functions and displays
that seemed obvious to the software producer may not be obvious at all to the new user.
The best vendors have experts who can solve problems by phone or e-mail the same day.
1. Vendors
Over a dozen vendors are currently in the R&M support software business. In
general, their products are associated with the normal R&M tasks: prediction and
allocation, fault trees, FMECA, mission simulation, etc. No single vendor touches all the
analytical bases, but four of them, Relex, ReliaSoft, Item and Isograph, each offer a suite
of programs that can share a common project system description.
Figure 1
SELECTED VENDOR LIST
Isograph Incorporated
8001 Irvine Center Drive
Suite 1430
Irvine, CA 92618
(949) 502-5919
www.isograph-software.com/
Fax: (949) 502-5933
Item Software, Inc. (USA)
2190 Towne Centre Place, Suite 314,
Anaheim, CA 93806
(714) 935-2900
www.itemsoft.com
item@itemsoft.com
Relex Software Corporation
540 Pellis Road,
Greensburg, PA 15601
(724) 836-8800
www.relexsoftware.com
info@relexsoftware.com
ReliaSoft Corporation
ReliaSoft Plaza
115 S. Sherwood Village Drive,
Tucson AZ 85710
(888) 886 0410
www.reliasoft.com
sales@reliasoft.com
2. Coverage
Reliability engineers usually think of a system’s life cycle in terms of phases:
concept development, system design, parts selection, prototyping, production, and field
operation. The phases may have other names and their boundaries may be blurred while
different parts are in different stages of development but whatever they are called, each
phase can be associated with certain R&M tasks.
Figure 2 lists common R&M tasks that are considered appropriate to each phase of a
system’s life cycle. These tasks may change their form over time, for example data
analysis may begin during design with analyses of component experience, and then, once
prototypes have been built, refocus on test results; and finally on system performance in
the field. The tasks that are fully supported by at least one of the four vendors listed
above are shown in color.
Figure 2
MISSION PHASES AND R&M TASKS
Tasks supported by vendor tools shown in color
Concept
& Design
Parts
Selection
Prototype
Production
Field
<======================== Reliability Program ====================== >
<===== Prediction ======>
<== Allocation ==>
<====== FMECA ======>
<==== Risk Analysis ====>
<==Fault Tree Analysis===>
<===================== Mission Simulation ===================>
<=================== Data Statistical Analysis ========================>
<============ Life Cycle Cost =============>
<===== Failure Reporting and Corrective Action =====>
<========== Reliability Growth Analysis =========>
<======= Maintenance Planning =======>
<= Reliability Test =>
<===== ALT =====>
<== Maint Demo ==>
<= Quality Control =>
<= Parts Screening = >
<== Age-==>
Reliability
3. Standards
R&M tools are concerned with two kinds of standards: standard definitions and
procedures for performing R&M tasks, and standard libraries of device failure rates:
Over the past few years the Department of Defense has phased out U.S. military
standard procedures and data bases, to be replaced by new American and international
commercial standards. The Mil-Stds can no longer be made mandatory in government
contracts and are no longer updated, but some old favorites are still in effect for optional
use. Today there are a great many international and manufacturers’ association standards
to choose from. This report lists only those supported by at least one of the selected
R&M tool vendors.
Some standards for reliability prediction are associated with failure data libraries.
R&M prediction, allocation, fault tree, failure modes effects and criticality analysis
(FMEA/FMECA) and mission simulation tasks may draw on these libraries of device
failure rates. Each library lists thousands of devices and their known failure rates under
various operating conditions and (in some cases) different quality levels.
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Mil-Hdbk-217F notice 2, the old warhorse for electronic devices
Bellcore TR-332 Reliability Prediction Procedure for Electronic Equipment
(also called Telcordia SR-332)
The Reliability Analysis Center’s PRISM, which is primarily for electronics
but incorporates infant mortality, reliability growth and software.
The French CNET 93, which is similar to 217 but more up to date
British HRD5, which is simpler
International Electrotechnical Commission TR 62380 (formerly RDF 2000),
for telecommunications electronics, developed in France by the Union
Technique de l’Electricite
Chinese GJBz 299B parts stress
The Naval Surface Warfare Center’s NSWC Mechanical, for non-electronics
NPRD 95, Non-electronics Parts Reliability Data, by RAC
NOTE: The Mil-Hdbk-217 and NPRD libraries have not been updated for many years
and are not recommended. Other libraries, notably the Italian Italtel RPH 2003, are not
available with any of the products covered in this survey.
Some vendors offer commercial data packages to extend the standard libraries, and
provide for users to add their own data.
Other tasks may employ procedural standards such as Mil-Hdbk-472 for
maintainability prediction, the Air Transport Association’s MSG-3 for maintenance
planning, and the Society of Automotive Engineers’ J1739 for failure modes and effects
analysis. In all cases it is important to recognize tasks that will require options and
exceptions from the standard in order to suit a particular project, and determine which
tool has the necessary flexibility.
4. Data Sharing
Each of the four vendors listed above provides for sharing project data among its
tools that support R&M tasks. The user can create a common database of his project’s
system description, component failure and repair rates, functional requirements and
maintenance support strategy. Different tasks may assume different formats for the same
input data, for example data entered for mission simulation in reliability block diagram
form may appear for other tasks in level-of-indenture tree form or in spreadsheet tables.
This kind of data sharing greatly simplifies the R&M Manager’s ability to
synchronize experimental alternatives, design changes and data updates in all on-going
tasks. It also provides for freezing project data in order to produce a set of analyses as of
a given date, and then releasing an update for the next set.
In any case, expect the common project database itself to be stored in a format that is
unique to the vendor. Some vendors provide for automatic translation to a conventional
industry format such as Computer Aided Design, Logistic System Analysis, Microsoft
Excel and Access, or delimited text. However, the initial setup for such transfer may
require work by an expert in computer data export-import.
5. Tool Capabilities
Vendors’ brochures cite the special-purpose advantages of their products. These
documents can help eliminate some candidates that plainly are unsuited to the user’s
needs. If requested, for further selection, vendors may be willing to provide user
manuals, which require much more study but clarify the tool’s options and features from
a user’s viewpoint, give a feel for the degree of user-friendliness, and offer a starting
point for technical discussion with the vendor.
One significant feature concerns the production of displays. The presentation of
results to others who are not R&M experts is an essential part of the R&M manager’s
work, and good graphics can be crucial to his success. Vendors vary widely in the
potential they offer for data display, and in the degree of user effort required to produce
displays. User manuals are a good source for evaluating the graphics options and amount
of learning involved in using them
Important mathematical features include the statistical distributions of failure and
repair that can be identified through data analysis and then input to models; reliability
growth analysis methodology; and measures for quantitatively ranking components by
their R&M importance. Mission simulators may represent single- or multi-phase
missions and may employ Markov, analytical (closed-form), or Monte Carlo (open-form)
algorithms; each has its advantages and disadvantages.
6. Vendor Support
One vendor (Isograph) is a British firm with a U.S. distributor and the other three in
this survey are American, but all are well established in the U.S. and responsive to user
requests for assistance.
Each vendor packages technical support with the tool in some combination of:
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Comprehensive R&M guidebooks
Hard-copy or e-mail newsletters and magazines with articles and tips for users
For a period of time, such as 3 months, access by telephone to a
knowledgeable engineer who can usually answer questions on-line, or at most
in a few hours
For a further period, response to e-mail, normally with a one-day turnaround
For some period, such as until the next release, free or reduced-price software
upgrades
A free web library of technical articles
Extra-cost long-term support contracts for technical advice and free or
reduced-price upgrades
Regional or on-site classes, free or for a fee, on the use of specific products.
NOTE: ReliaSoft is unique in providing technical support to users by phone, fax, and email for an unlimited period.
7. Products
Figure 3 on the next page lists the R&M tools marketed in the U.S. by four vendors
who offer support of several R&M tasks sharing common project data.. In some cases
the method, standard, or other characteristic is shown, to indicate major differences
among vendor programs.
For a more complete listing and descriptions of R&M tasks, see MIL-STD-785B.
Although cancelled long ago and now somewhat out of date, it is arguably the best R&M
standard ever written, because it: (a) presents a menu of tasks from which the user may
choose those appropriate to the target project, and (b) strongly recommends tailoring the
standards to suit the user’s needs. 785B and other MIL-STDs may be downloaded at no
cost from http://www.weibull.com/knowledge/milhdbk.htm
Task
Field and Test
Data Analysis
Reliability
Prediction
Maintainability
Prediction
Accelerated
Life Test
FIGURE 3
SUMMARY OF R&M TOOLS
Isograph
Item*
Relex
Weibull
4 distributions
(also Allocation)
217, Telcordia,
NSWC, 299B,
62380, PRISM
MTTR
Mil-Hdbk-472
Event Tree
FaultTree+
Measures of
importance
p/o FaultTree
Importance
Mission
Simulation
AvSim+
Monte Carlo,
Multi-phase
Network
Simulation
NAP
Importance
Fault Tree
Maintenance
Planning
FMECA
Life Cycle Cost
Quick
Simulation
Reliability
Management
RCMCost
MSG-3, Spares
optimization
FMECA
7 standards, Risk
Weibull
8 distributions
(also Allocation
and Derating)
217, Telcordia,
NSWC, 299B,
62380, NPRD5
MainTain
Mil-Hdbk-472
(also Allocation)
217, Telcordia,
NSWC, CNET,
HRD, 299B,
62380, PRISM
Maintainability
Mil-Hdbk-472
FaultTree
15 distributions
Fault Tree
Measures of
importance
p/o Fault Tree
Importance
Event Tree
Importance,
Consequences
RBD
Closed-form,
Single phase,
Importance
SpareCost
Spares
Optimization
FMECA
1629, BS 5760,
SAE J1739, ISO
9000, IEC 61508
lccWare
AvSim+/RBD
Multi-phase
Markov
Multi-phase
RBD
Closed-form or
Monte Carlo,
Multi-phase
BlockSim
Monte Carlo,
Single phase
OpSim
Spares
Optimization
FMEA/FMECA
10 standards
MPC 3
MSG-3, Spares
optimization
Xfmea
4 standards, ISO
9000, Risk,
Enterprise grade
LCC
p/o BlockSim
Markov
Single phase
Markov
Multi-phase
FRACAS+
Reliability
Growth
Analysis
*Item also distributes ReliaSoft products.
Reliasoft
Weibull++
10 distributions,
2 upgrades
Lambda Predict
(also Allocation)
217, Telcordia,
NSWC, 299B,
62380
p/o BlockSim &
p/o RCM++
ALTA
PRO upgrade
BlockSim FTI
Measures of
imporance
Markov
Single phase
BlockSim
Single phase
FRACAS
p/o FRACAS
Reliability curves
XFRACAS
Web-based,
Enterprise grade
RGA
8 Models,
Statistics,
PRO upgrade
8. Isograph
Isograph offers the “Reliability Workbench” suite of closely related modules,
together with independent R&M tools. The Workbench modules and the independent
tools can all share common user data defining the project system configuration and
failure and repair data, in the vendor’s unique format. They all can import data from
CAD and other sources; send output to either Isograph pre-defined tables and graphs or to
customized text reports, graphs and diagrams; and exchange data with Microsoft Access
data bases, Excel spreadsheets; and text files. Web site www.isograph-software.com
describes the program features and technical specifications, and you can download
demos. (Isograph also offers RiskVu and HazOpPLUS, two programs that can share the
common project data but are not discussed in this survey.)
The Workbench modules are accessed as tabs in the Workbench home interface:
Prediction, FMECA, RBD, MTTR, FaultTree+ and Markov.
Prediction software has five optional failure data library modules: Mil-Hdbk-217,
Telcordia, NSWC, IEC 62380, and 299B. 217 includes parts count and stress methods.
Telcordia comes with three procedures: steady-state, one-year and mixed (library, field
and test) data. The user may extend the standard libraries with additional data taken from
manufacturers’ spec sheets and other sources. Workbench also offers a link to the RAC
PRISM library. The predictions also support reliability allocation with a choice of
models.
MTTR prediction is incorporated into Prediction, and conforms to Mil-Hdbk-472.
For maintainability prediction the user adds his own maintainability data, either by
entering part MTTR values or by a guided analysis of the step-by-step repair process.
The FMECA module conforms to Mil-Std-1629A, British BS 5760, aeronautical
FMEA, SAE ARP5580 and SAE J1739, and accepts user modification to the standards.
The user can adopt two approaches: a functional approach during system design or a
hardware approach after component selection. Failure modes can be assigned at any
level and can be defined as detectable or non-detectable. The module includes an
apportionment library derived from Mil-Hdbk-338 that aids the user in grouping
commonly used components and failure modes. The program creates a handy lexicon of
user phrases. Users may also add the optional Design and Process FMEA upgrade, which
accepts detection rankings and evaluates risk.
Isograph’s RBD module solves reliability block diagrams for basic system figures of
merit such as reliability, availability, mean time to failure and expected number of
failures. Component failure and repair rates are limited to the Exponential statistical
distribution and single-phase missions. The simulation engine uses minimal cut-set
algorithms. Component importance (ranked responsibility for system failures or
downtime) is measured in the user’s choice of four methods. The module also evaluates
common cause failure factors and can conduct simple sensitivity analyses by
automatically varying selected input values.
FaultTree+ integrates fault tree, event tree and Markov analysis. The software employs
minimal cut-set algorithms to solve for fault tree top events, common cause failures
(CCF), and a choice of four measures of importance. For weighted event tree
consequences, it evaluates CCF, uncertainty, sensitivity, and importance. FaultTree+
also offers an optional Dynamic Link Library which allows users to construct
applications, using C or Visual Basic language, and interface them directly with
FaultTree+, for example other programs can run fault tree functions. FaultTree+ has
been used on large trees to the order of 20,000 gates and events and can solve even larger
trees.
The Markov simulator is integrated into Isograph’s Fault Tree software. It can share
project system models or accept interactive inputs in reliability block diagram, fault tree
or transition diagram form. It can simulate multi-phase missions in which the system
configuration and requirements vary at fixed times. Markov also accepts time-dependent
failure rates that are phased-Weibull distributed. The simulation employs numeric
solution of the Markov differential equations to calculate a wide variety of system figures
of merit.
AvSim+ is a mission simulator that can model system availability and reliability over
a mission that may consist of a sequence of operational phases. The user may enter
system configuration data in either fault tree or reliability block diagram form,
accompanied by failure and repair rates and optional man-hours and spares data. Failures
and repairs may be Exponential, Weibull, Normal or Lognormal distributed. The user
may also enter spares constraints and costs at three supply echelons, labor constraints and
costs, and safety and environmental effects.
The simulation employs a Monte Carlo engine that calculates mission availability and
reliability, and optionally man-hours, spares, safety and environmental consequences, at
any level of system configuration. The relative significance of system components is
indicated by their unreliability, with a choice of median, 90% or 95% confidence. A
report generator can produce pre-formatted or customized graphs and tables, which can
be displayed directly or inserted into Word reports
Weibull is a module of AvSim+, RCMCost and FRACAS+ that supports statistical
analyses of field data. The user can select one of several distributions including
Exponential, Normal, Lognormal, Weibayse, and seven variations of Weibull for
designated fields in the user’s project data base. The program calculates the MTBF or
MTTR mean value and other statistics.
RCMCost is a Reliability-Centered Maintenance planning tool that conforms to
MSG-3 and Mil-Std-2173. It assists the user in entering or importing system FMECA
data and structuring it in MSG-3 form, analyzing failure experience to develop a
preventive maintenance plan or update it, compare maintenance strategies, predict
maintenance man-hours and spares demands, and prepare either standard or tailored
reports.
lccWare is the Isograph life cycle costing tool. It aids the user in defining a cost
breakdown structure, entering mathematical functions for cost elements, and estimating
ownership costs at user-defined points in the system’s life cycle. The cost functions can
be entered in Visual Basic-compatible language and the variables may be timedependent. A “Part Tree” capability simplifies data input for frequently used equipment,
and lccWare aids the user in creating a cost element library and establishing data security.
NAP is a tool for creating and analyzing a network diagram. The user defines
network nodes and the communication links among them, including bi-directional paths.
NAP can analyze networks that cannot be modeled in conventional reliability block
diagrams. NAP assists in creating user parts and element libraries. The network analysis
employs minimal cut set methodology to calculate system availability and reliability.
NOTE: Markov tools have a similar capability, but as systems grow in complexity, their
Markov models become more difficult to create and validate.
FRACAS+ supports the Failure Reporting, Analysis and Corrective Action System
method of monitoring and managing product reliability. It aids the user in structuring a
data base of equipment descriptions and locations and entering failure reports and
corrective actions. FRACAS+also assists in browsing failure reports by equipment or
location, analyzing the data for Weibull or other statistical distribution, and tracking
subsequent actions.
NOTE: Although not part of standard FRACAS, a complete reliability management
system might include a formal Failure Review Board or other management responsibility
for reports discipline, configuration tracking, and assigning and following-up member
actions. These functions are not directly supported by FRACAS+.
9 Item
Item Software offers a “ToolKit” prediction and analysis suite and two related quality
assurance programs, Design FMEA and Process FMEA. All of the programs share
common project data. Input can be by a combination of RBD, level-of-indenture tree,
and tabular grid graphics. Export-import data formats include Excel, Access and
delimited text. Users can customize the toolbars and tailor the output report formats.
Diagrams, charts, tables and diagrams, including reliability block diagrams, are
compatible with Microsoft Word. Item’s Multi Document Interface manages target
project data sharing.
Item also distributes six ReliaSoft products: Weibull++, Xfmea, ALTA, BlockSim,
MPC and QTMS; RAC PRISM; iQRAS risk assessment; and three TFD Group programs
for life cycle costing, spares optimization, and total ownership cost. These tools are not
participants in the Toolkit project data management system.
The ToolKit suite includes five optional prediction modules: MIL 217 (Mil-Hdbk217F), Bellcore (Telcordia R332), Mechanical (NSWC), IEC 62380 (ex-RDF 2000), and
China 299B. Add-on library packages are available including electronic devices and
non-electronic NPRD 95. The prediction modules contain five allocation and seven
derating methods. The system hierarchy may incorporate redundancy.
RBD is the ToolKit’s mission simulation module. It is limited to single-phase
missions but can generate 15 statistical distributions of component failure and repair
times. The simulation engine converts the user’s system description to minimal cut-set
logic and calculates system figures of merit by solving differential equations, using the
Latin Hypercube sampling technique. Results are displayed as reliability, availability and
related figures of merit at user-designated system and subsystem hierarchical levels. The
simulator also rates each component’s impact on system R&M performance by a choice
of three importance measures.
The Markov module calculates system figures of merit at discrete or continuous
intervals along a multi-phase timeline. Input is in the form of Markov transition
diagrams, guided by a model editor that draws on the system data base. Component
failure, repair and other transition rates are limited to the Exponential statistical
distribution. The simulation engine operates by closed-form solution of differential
equations to calculate reliability and availability figures of merit. Markov analysis is
especially useful for mission simulations that consider degraded system states, and for
optimizing operation and repair strategies.
Item FMECA (Failure Modes Effects and Criticality Analysis) conforms to Mil-Std1629A and standards that have replaced it, including British BS 5760, SAE J1739 and
IEC 61508. Input is by hierarchy tree (level of indenture), tabular text, or a customizable
sreadsheet-like grid. A large phrase library may be customized by the user. There is also
a Mil-Hdbk-338 failure mode apportionment library that can be accessed manually or
automatically when transferring system data from a prediction module. The program
automatically rolls up the end effect to the failure mode at the next higher level. For
special analyses the user can relate failures to multiple effects and redefine the severity
categories.
Fault Tree analysis identifies and ranks the combinations of events that can lead to
system failures. Users construct the tree via the drawing canvas or through the system
tree view. The input screens have a comfortable intuitive feel with familiar cut-and-paste
and drag-and-drop operation. The fault tree module provides 15 distributions and allows
for time phase analysis.
Item ARALIA works with Fault Tree to enhance its capabilities. Aralia is a recently
developed mathematical technique for quick decision processing that produces precise
results rather than approximations. It also provides for the statistical distribution of
failure probabilities, computes exact measures of event importance, supports time
dependent analyses, and can model incoherent fault trees.
SpareCost is a ToolKit module that employs the British RepStock and OptCost
models and algorithms. SpareCost optimizes spares stock costs at two repair echelons for
a specified out-of-stock risk. Parts data is structured in configuration trees. The analysis
assumes that the system is serial (all parts are equally important), skilled repairmen are
available, and repair time is insignificant. Output reports include parts stock levels, costs,
and performance over user-defined periods.
Maintain can share system data with other ToolKit modules. It conforms to
procedure V method A of Mil-Hdbk-472. The analysis is an extension of reliability
prediction that is used to predict system downtime, maintenance manhours and costs, and
identify problem areas. Maintenance activities are characterized by procedural steps.
Item Software also offers a suite of quality assurance modules that can share project
data with the ToolKit modules. Of these, Design FMEA, Process FMEA and iQRAS are
of special interest to reliability engineers. The first two are special FMEA applications
that simplify and discipline data collection and access in support of design, process and
control management. They meet the requirements of ISO 9000, SAE J1739 and
automotive QS-9000. iQRAS is a quantitative, multiphase mission risk assessment tool.
10. Relex
Relex Software is the vendor of the “Relex” prediction and analysis suite, as well as a
user-customizable FRACAS platform. The programs can share common data (system
configuration and component failure and repair rates), under management of a central
Project Navigator. The data format is unique to Relex products. Or data can be
transferred externally by CAD or delimited text import-export. Standard reports and
graphs are provided for presentation of results, all of which can be customized.
The “Relex” suite consists of 17 optional modules for reliability prediction, data
analysis and other support. Nine of them are prediction modules, based on a choice of
standards: Mil-Hdbk-217, Telcordia, NSWC, 217 Parts Count, PRISM, CNET, HRD,
299B and IEC 62380. Each module comes with the related standard procedures and data
library. All of the prediction modules also support reliability allocation. Library search
aids, for example by part number, are included. Or users may enter their own test data
and get an extrapolation of the failure rate. PRISM data analyses can be applied to the
other libraries.
In addition to the prediction modules, the Relex suite includes eight optional R&M
analysis modules: Weibull, RBD, OpSim, Markov, FMEA/FMECA, Fault Tree/Event
Tree, Maintainability, and LCC..
Weibull analyzes field histories and test results to find the best fit among eight
statistical distributions of failure and repair data: Weibull, Normal, Exponential,
Lognormal, Gumbell +, Gumbell –, Rayleigh or Weibayes. A test plan calculator and
general statistics calculator are included. The user can display confidence bounds and
overlay data sets for direct comparison. Failure and repair data can be directed as inputs
to system prediction, FMEA and simulation modules, and Monte Carlo simulation results
can be directed to Weibull for statistical analysis.
RBD is a multi-phase mission simulator. It models system configuration, component
failure and repair rates and system requirements. Where possible it uses quick closedform algorithms to solve for reliability, availability and other figures of merit against
system requirements. Otherwise it employs Monte Carlo mathematics to calculate the
system figures of merit. Component rates may be in any of the statistical distributions
determined by Relex Weibull analysis. RBD can operate either stand-alone or linked to
the prediction modules, and can also convert data from CAFTA format.
The OpSim simulator model is an extension of RBD that optimizes system
maintenance procedures and guides maintenance planning. The model encompasses onand off-site repair teams, spares, preventive maintenance and inspection schedules, parts
and labor costs, and aging. The optimizing objective may be cost, reliability, or capacity.
Markov is a closed-form simulator that accepts system state sequences in the form of
Markov transition diagrams and employs cut-set algorithms to calculate mission
reliability, availability, MTBF, MTTR and other figures of merit. The mission consists
of a single phase of system operation and requirements, and component failure and repair
rates are limited to the Exponential distribution. Markov models are especially useful for
analyzing common cause failures, degraded states and other cases where the sequence of
events is important.
The FMEA/FMECA module supports failure modes, effects and criticality analyses,
using the same data libraries as the prediction modules. The project system configuration
may be entered graphically in either tree (level-of-indenture) or tabular (spread sheet)
form. Procedures conform to the user’s choice of application and standards: Process,
Design, Piece Part, Mil-Std-1629, SAE ARP5580, Ford, GM or Daimler-Chrysler.
Results are compatible with logistic system analysis (LSAR) format.
The Fault Tree/Event Tree module supports both fault tree and event tree analysis.
(Fault and event trees model system failures or events, structured as logical sequences.)
The program applies cut-set algorithms for quantitative solution. It offers Lambda-Tau
representation of well-maintained systems, supports disjoint-event simplification of the
tree, and has a neat tree-pruning feature. The user has a choice of four standard
procedures and three measures of component importance: Birnbaum, Criticality or
Fussell-Vessely.
An advantage of fault tree analysis is that it can represent human errors and
subsystem-interface failures that are not usually considered in other models. It is the
user’s responsibility to include them.
Maintainability is an extension of reliability prediction that forecasts system
maintainability as a function of component failure modes and maintenance times.
Maintenance actions can be modeled in up to seven procedural steps conforming to MilHdbk-472. Results are consistent with LSAR format.
LCC is a life cycle cost model. It accommodates inflation factors, net present value,
and cost- or work-breakdown structure. LCC allows users a choice of parametric,
analogy, bottom-up or direct procedures, estimates design, production, warranty, repair
and disposal cost, and makes net present value calculations. It provides an industry
standard cost breakdown structure, modified by user-defined cost functions, and
generates standard or user-tailored reports.
The FRACAS (failure reporting, analysis and corrective action system) package
provides a systematic way to organize and discipline failure data collection, examine data
statistics using optional analytical programs, and assign and track corrective action. It is
ISO 9000- and TickIT-certified.
Relex offers FRACAS at three optional editions: Team, Corporate or Enterprise.
The Team edition gives users the choice of a secure web browser or access to Windows
data bases of system failures and other incidents, and aids in scoring departmental
responsibility for failures, analyzing trends, and generating reports. The Corporate
edition provides an SQL data base and assists the user to create custom data forms and
tables, calculate MTBF and MTTR values, link to prediction results and Weibull
statistical analyses, perform user-defined calculations, and create unique reports. The
Enterprise edition can interface with several concurrent data bases, including those
managed by SQL and Oracle, and track multiple products and participants. Depending
on the edition, standard and optional modules may help the users monitor the data base
and trigger alert messages; keep audit histories of incidents, design changes and other
data; maintain security; assist in organizing projects, and assign and track actions.
11. ReliaSoft
ReliaSoft Corporation’s products include Weibull++, ALTA, BlockSim, RGA,
Lambda Predict, Xfmea, RCM++, MPC3 and XFRACAS. All of them can share a
common set of project data, and all output reports are compatible with Word and Excel.
The vendor has also introduced RENO, a useful simulator.
Weibull++ examines field and test failure data and finds the best fit among several
statistical distributions: Exponential, Normal, Lognormal, Weibull, generalized Gamma,
Logistic, Loglogistic, Gumbell, Weibull-Bayesian, mixed-Weibull (with up to four
subpopulations), or competing failure modes. Software is included to support nonparametric, warranty, degradation, and recurrent life data analyses, and test planning.
Weibull++ DE (Developer Edition) is an extra-cost upgrade that allows users to write
their own applications using ReliaSoft’s math and plotting engine.
The ALTA program supports quantitative accelerated life testing (testing under high
operating and environmental stress to forecast the effect of aging on reliability) where the
applied stresses are not a function of time. Although accelerated tests are normally used
to precipitate failures, ALTA supports forecasting long-term reliability in normal use.
The program guides a choice of Arrhenius, Eyring, Inverse Power Law and other life-
stress models. From test data the user can determine such parameters as chemical shelf
life, system mean time to failure, B(x) life, failure modes, and warranty factors. The
program employs maximum likelihood estimation and is integrated with Weibull++ to fit
a Weibull, Exponential or Lognormal statistical distribution and calculate confidence
bounds. A report generator produces tables and automated 2D and 3D plots.
An ALTA PRO upgrade provides additional models for analyzing time-dependent
stress profiles or up to eight simultaneous stress columns.
BlockSim is the ReliaSoft mission simulator. BlockSim is limited to single-phase
missions. It accepts user system data by reliability block diagrams, fault trees, level-ofindenture trees, or spreadsheet tables. Failure and repair can be assigned any of the
distributions that Weibull can identify, or data can be imported directly from Weibull++
or ALTA. The diagrams can be solved analytically (closed form) and cost-based
optimizations and reliability allocations can be performed based on this closed-form
solution. Alternatively, the main simulation engine is Monte Carlo, including quick
calculation of subsystem performance. The simulation includes inspection and
preventive maintenance, crew and spares policies and costs. Users can create and
beautify an unusually wide variety of graphics in support of preparing input data, drawing
conclusions and presenting the simulation results.
BlockSim FTI is an upgrade to BlockSim that supports fault tree analysis. User input
can be a mix of reliability block diagram and fault tree graphics.
RENO is an unusual stochastic event simulator that can perform simulations and
spreadsheet calculations employing a novel graphic user interface. The user defines
entities and flowcharts a model for Monte Carlo probabilistic solution. Inputs may be
assigned 20 distributions including Normal, Weibull, and Exponential.
NOTE: RENO is a useful stand-alone tool for the reliability analyst but not limited to
R&M applications. To share project data with the ReliaSoft R&M suite, it must be
printed out.
MPC 3 conforms to the Air Transport Association’s MSG-3 standard for creating and
optimizing maintenance plans. It guides the user in:


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Establishing a system data base using standard aeronautical work structure
numbering and attaching documents in Word format.
Identifying maintenance-significant items and describing related functions,
failures, causes and effects
Assisting Maintenance Review Boards in assigning tasks, developing and
updating a maintenance program and preparing reports in ATA format.
Xfmea is a FMEA and FMECA (failure modes effects and criticality analysis) tool. It
supports SAE J1739 and ARP5580, AIAG FMEA-3, and Mil-Std-1629A and allows
customization to other standards. It conforms to ISO 9000 and Six Sigma guidelines, and
can be configured to the client’s analysis and reporting procedures. Xfmea offers a
choice of FMECA or of design, process, machinery, system or service FMEA, and
includes risk analysis. Input and editing may be in tabular (spreadsheet) or tree (level-ofindenture) format. Output displays provide for recommended actions and follow-up
status.
Xfmea is available in an Enterprise edition that is compatible with SQL data bases.
XFRACAS is FRACAS software that the user accesses on the web to acquire,
manage, analyze and resolve product failure data. The data may reside in an SQL or
ORACLE database. Features include system tracking, customized queries and reports,
and a configurable user interface. XFRACAS also supports the user’s Failure Review
Board in establishing test and field incident reporting procedures, tracking systems,
conducting data analyses, assigning and tracking corrective actions, querying the data
base, and preparing reports.
RGA supports reliability growth analysis, a method of forecasting the degree of
system reliability and maintainability that can be achieved, tracking progress, and
generating reports. ReliaSoft’s standard version is intended for use during system testing.
A test planning utility is included. The test data may be continuous time-to-failure or
discrete failure. The user has a choice of eight statistical models: Crow-AMSAA, Crow
Extended, Power Law, Duane, Gompertz, Modified Gompertz, LLoyd-Lipow and
Logistic. Depending on the data type, the program employs either maximum-likelihood
or least-squares algorithms to calculate system figures of merit including MTBF,
reliability and failure rate (intensity), as well as goodness-of-fit and trend analysis. The
user can generate a variety of graphics and prepare reports for export into Word or Excel.
An RGA PRO upgrade adds support of reliability improvement programs for fielded
repairable systems. It includes Power Law and Crow Extended models for reliability
projection and advanced techniques for data analysis.
12. Technical Support
Isograph supports users by telephone, web meetings, e-mail and fax for 4 months at
no cost following their purchase. Isograph also offers extended technical support and
maintenance contracts that include upgrades to their products. Isograph can also provide
utilities and services to convert models from obsolete software products.
Isograph offers two annual User Group meetings in the United States; schedules
regular one-day courses in their products at Newport Beach CA, Washington DC and
Warrington UK; and will arrange other courses there or on site. Isograph logs user
queries and solutions, and requests for program enhancements. The Customer area on
Isograph’s web site provides up-to-date information on program releases, user group
presentations, user requests, utilities, etc.
Item provides with each module a free three-month maintenance contract that covers
technical support, product updates and web-based training classes. Most technical
questions are answered immediately; a few may require 24 hours to resolve. Failure data
libraries are updated monthly, at no cost.
Item publishes a monthly newsletter of product bulletins and training course
announcements. Their web site’s Tech Corner offers tool tip videos and articles on R&M
practice. Item schedules 2-, 3-, and 4-day courses and workshops covering basic theory
through advanced methodology in Anaheim, CA and College Park, MD. Attendees
receive 45 days’ use of the ToolKit suite of products.
Relex supports buyers free for 3 months, including technical support by phone,
software and library upgrades, free instructor-led on-line training, and a discount on
classes. After 3 months, technical support by e-mail or fax is still free and the vendor
will furnish program and data upgrades at a reduced price. Long-term support contracts
are available.
Relex publishes QuarterFlash, a hard-copy quarterly newsletter that describes new
products or upgrades and contains a helpful column of tips to users. The vendor will
conduct a three-day course at the site of a major customer, schedules about ten free
training courses for users around the country every year, and has developed an interactive
training CD called Reliability 101 that is included with every software purchase. Helpful
articles concerning the selection and use of Relex tools also appear on their web site.
Reliasoft provides unlimited free technical support and minor software updates to
registered users via phone, fax, e-mail and web meetings. User manuals are accompanied
in most cases by a reference handbook. Reliasoft publishes the Reliability Edge
newsletter, posted on the internet or in hard copy by free subscription, and posts or emails Reliability HotWire, an e-magazine that includes useful how-to information. The
vendor publishes four on-line textbooks. A free web site, http://www.weibull, has
thousands of pages of technical papers. Reliasoft offers a free seminar as part of an
annual users group meeting, and also conducts five collections of courses for a fee:
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About two dozen five-day seminars a year, on different subjects and in
different cities world wide,
Three- and five-day training courses on R&M tasks,
One-day courses in R&M management,
Two- and three-day courses on related quality/reliability topics, and
Three-, four- and five-day courses in preparation for advanced subjects.
13. Prices
The cost of R&M tools is not as important as it may seem, considering the far higher
cost of the professional hours required to learn and apply them, not just by R&M analysts
but by the demands on design engineers and production, operations and maintenance
supervisors.
The vendors included in this survey are highly competitive and the costs of their
products would probably be similar to the rough estimates shown in Figure 4, if their
pricing were similarly based. The vendors structure their products differently, for
example some tools incorporate other tools, or require other tools in order to operate.
ReliaSoft prices are posted on their web site. The other vendors will quote current prices
by phone or e-mail.
Figure 4 illustrates typical prices of unbundled single items, licensed to a single user
and bought outright, rather than rented or accessed on the internet.
Figure 4
Typical Cost of Single User License for Purchased Product
Task
Data Statistical Analysis
R&M Prediction
(1 Library)
R&M Prediction
(4 Libraries)
Mission Simulation
FMECA
Maintenance Planning (MSG-3)
$ Cost *
1,000
2,000
6,500
2,500
2,000
5,000
Training
Instruction at vendor’s site, per person, 1 day
At vendor’s site, per person, 3 days
At customer’s site, per classroom, 1 day
At customer’s site, per classroom, 3 days
500 – 750
1,000 – 1,500
3,500**
8,000**
* Prices will be higher for multi-user site license or with add-ons, lower for rental
or for internet operation
** Plus instructor’s expenses
For new releases, bargains are usually offered to early shoppers and to upgrade
current customers to the new release level. Unadvertised discounts are available for
academic or government buyers. And total cost can often be significantly reduced for
tools purchased in volume or bundled with other tools, training packages, or extended
maintenance (warranty). Extended maintenance typically consists of some combination
of long-term technical support by telephone and free upgrades to new releases.
Isograph offers various price options for single-user licenses, network license and
special packages that include software products commonly used together. Extended
maintenance follows a descending discount structure that is dependent on the length of
the maintenance agreement.
Item offers site and network licenses, sold by module and number of concurrent
users. Discounted combination packages are available for the most commonly used
configurations. Call or e-mail them at the telephone number and address shown in
paragraph 1.
Relex: For prices contact Relex directly at the telephone number or e-mail address
listed in paragraph 1 above. Relex products can be bought outright, or accessed on the
internet for a user fee.
ReliaSoft maintains an updated price list on the web at http://www.reliasoft.com
/order_form.htm. Network license and multi-user site license prices are available on
request. A “Gold License” is available that includes all of ReliaSoft’s shrink-wrapped
tools and one training course per year. Software can also be rented at an annual cost of
half the retail price.
Extended maintenance costs 20%, 30% or 45% of the retail price for 1-, 2- or 3-year
terms. .
14. A Whiff of Snake Oil
A final note: Some enthusiastic software marketers publish brochures and
newsletters making it seem that their products can substitute computer tools for
engineering expertise. Be not deceived. Even in the computer age it is still true that the
single most important factor in any system analysis is how well the analyst understands
the system. And engineers, operators and maintainers must still provide valid input
information, and must still assist in translating the outputs into practical
recommendations for action.