Memo Report
To: David Thacker
From: Desiree Reed
Subject: Technical Definition and Description (Assignment 3)
Date: October 18, 2013
Introduction
For this assignment, our class was required to write a technical description and definition that
pertains to our field of study. I selected “Statics” as my word because I’m a mechanical
engineering major, and it is one of the subjects that beginning engineering students study.
Audience
My audience for this assignment is second-semester engineering students. The audience will
have basic understanding of physics and most likely have already taken some sort of introductory
engineering class. For this reason, terms like stress, moment, and forces are not defined because
they are covered in the introductory course as well as basic physics which many engineering
students have already taken or are taking currently.
Need and Placement
The technical definition, which will be placed in a course catalogue, will provide students who
are taking the class with a simple description of what the course and topic are about. The course
catalogue is one of the few adequate places for a definition this short to be located. The
definition will help them decide whether or not to take the class at that point in their curriculum.
It may also be the first time they have seen the word in their life, and a thorough definition is
useful for communicating the idea of what the word really means.
The technical description will communicate what statics is and how it applies to the world. The
description is placed in the introductory chapter because that is the most probable and
appropriate location where it will be seen and referenced. The description also provides a
preview of how Statics will be used in their engineering career and education.
Visuals
The first figure I used is a statics system that one might solve for a homework problem during
their statics course. It is located at the top to provide a general example of how statics is used.
The particular system used is a truss that one may see in the rafters of a building or on the front
of a store. The choice of the figure aimed at providing a familiar picture of how statics is used.
The following is the link to the picture used:
http://www.mathalino.com/reviewer/engineering-mechanics/problem-410-pratt-rooftruss-method-joints
The second figure I used is what we call a finite-element analysis of a bike frame. The reason
behind using a bike frame is because it is an everyday object that most people are familiar with,
and the use of a bike frame adds a little bit of cool factor to statics. The following is the link to
the source for figure 2:
http://www.mechanicalengineeringblog.com/2234-types-of-finite-element-analysis-finiteelement-analysis-capabilities-finite-element-analysis-engineering-services/
Rhetorical Choices
Throughout the technical description, the main objective is to provide a broad-based description of where
and how statics is used in the real world. Explanations are also provided for where and how students will
use what they learn in later coursework. The aim is to provide readers with examples of why statics is
important. Hopefully, it will provide some additional motivation to take statics seriously.
I took particular care in avoiding didactic prose by avoiding delving into specifics for each term used. It is
understood that they already are familiar with the terms used or will become familiar with them while
reading the textbook. The only term they may not know is second-moment of inertia, but it is covered
later in statics courses. The reader will not be able to do any statics just from reading the technical
description.
All of the technical description is written from my experience as an engineering student. There wasn’t a
necessity to use outside sources because I had already learned all of the material that I presented in the
description.
Audience: Students taking Statics for their engineering degrees
Problem: The word Statics sounds self-explanatory, and the subject is easy to shrug off as an
incoming engineer, but it is used so widely utilized that the audience needs to be informed of this.
Technical Definition
Placement: Course description
Statics is the analysis of non-moving parts in a system. It involves analysis of stress, forces, and moments.
This analysis later helps to determine it the part is likely to break under its expected load. Statics is widely
used in engineering to design systems.
Technical Description
Placement: Introductory chapter of a textbook
Statics analyzes forces and stresses on a nonmoving system.
Knowledge of this enables us to understand how an object will
behave over its lifetime. If the object has large loads on it, it
may break during service. If the loads are small, the object or
system may not require replacement for a long time. Statics is a
tool engineers use to predict how a product will behave once it
Figure 1. A Free-Body Diagram of a Statics
leaves the factory. New engineering students study basic statics
system.
first. The concepts learned can be applied to a vast multitude of
other engineering topics. Calculations done using basic statics concepts can even be used to come up with
estimates as well as solutions to engineering problems.
Students learning statics become familiar with moment analysis, shear and bending moments, and second
moment of inertia. Figure 1 is an example of a figure used to describe a statics problem. For example, the
problem statement may ask for the force or stress in section BC. While it is impossible to master every
aspect of statics in a single semester, understanding the basics is important to learning concepts and
applications taught in future courses.
Problem solutions in statics can become quite extensive and
involved. These problem sets may come up in later courses
such as mechanics of materials. It is relatively easy to find
solutions for simple geometries, but the more complex
geometries require more methodical procedures and sometimes
computer-aided modeling as well. For that, finite-element
analysis is used which involves static calculations for smaller
sections of the part.
When doing a finite element analysis, a mesh is selected where
the statics will be evaluated at each section of the mesh. As
seen in figure 2, finite-element analysis reveals specific points Figure 2. Finite-element analysis is done on a
bike frame. Red areas experience the most stress
where stress is the highest. Knowing this information is useful during this situation.
because points of high stress are where a part is most likely to break. Also, if there are welds there, they
are not as strong as raw material and the welds themselves may break depending on the analysis. The grid
of this mesh can be easily seen.
Part of statics involves the use of an equation solver such as TK Solver, EES, or Matlab, but while many
engineering modeling programs are capable of calculating loads, they still require a person who
understands the mathematics involved to utilize them accurately. Anyone who has used the above
mentioned approaches will easily testify just how hard it is to get accurate information with simply
plugging in equations or using the default settings on a finite-element analysis.