PSG COLLEGE OF TECHNOLOGY
COIMBATORE
DEPARTMENT OF METALLURGICAL ENGINEERING
COURSE: CAD, CAE AND CAM LABORATORY
COURSE CODE: 23Y411
NAME: AJAY PERUMAL
ROLL NO:23Y101
FINITE ELEMENT ANALYSIS ON SPANNERS
1. Introduction
A spanner, commonly known as a wrench in some countries, is one of
the most fundamental tools used in mechanical, automotive, and
construction industries. It is primarily designed to grip and turn
fasteners such as nuts and bolts. Despite its simple shape, the spanner
plays a vital role in assembly and maintenance operations. The tool
must resist bending, twisting, and breaking when subjected to forces
applied by users. This makes the strength and durability of a spanner
essential for safe and efficient operation.
When a force is applied to a spanner, it experiences mechanical stress
and deformation. Stress is the internal force per unit area that
develops inside a material, while deformation refers to the change in
shape or size of the spanner. Excessive stress or deformation can lead
to failure, such as bending or fracturing, which can be dangerous for
the user and may cause damage to the machinery involved. Therefore,
understanding these behaviours under load is critical during the
design and manufacturing stages of the tool.
Traditionally, physical testing was performed on prototypes to
determine the strength and safety of tools. However, physical tests are
time-consuming, costly, and sometimes destructive. With the
advancement of computational technology, engineers now use Finite
Element Analysis (FEA) as an efficient method to simulate and
predict how objects behave under different physical conditions. FEA
allows engineers to divide the spanner into many small elements and
calculate stress, strain, and deformation at each point, giving a
detailed insight into its mechanical performance.
In this project, ANSYS Workbench, a leading FEA software, is used
to analyse the structural behaviour of a spanner under load. A 3D
CAD model of the spanner is imported into ANSYS, where material
properties such as Young’s modulus, Poisson’s ratio, and yield
strength are assigned based on structural steel—the material typically
used for spanners due to its high strength and toughness.
A fixed support condition simulates the grip of a user holding the
spanner firmly at one end, while a force is applied at the other end,
replicating the torque applied during tightening or loosening
operations. The simulation results provide the magnitude and
distribution of stress and deformation, helping to identify critical
regions where failure may occur.
The main aim of this analysis is to ensure the spanner design can
withstand expected loads safely without permanent damage. This
virtual testing process saves both time and resources by reducing the
need for multiple physical prototypes. Furthermore, it allows
engineers to optimize the design for better performance and reliability.
2. Objective of the study
The main objective of this study is to perform a comprehensive Finite
Element Analysis (FEA) of a spanner to evaluate its mechanical
behaviour under typical working conditions. By simulating the forces
and constraints a spanner experiences in real life, the study aims to
understand how the tool responds in terms of stress, strain, and
deformation. This knowledge is crucial to ensure that the spanner is
safe, durable, and reliable for practical use.
Specifically, the objectives include:
To Model and Analyse the Spanner Geometry:
Create or import an accurate 3D CAD model of the spanner and
prepare it for finite element simulation. This step ensures the
geometry is correctly represented and ready for analysis in the
software environment.
To Assign Appropriate Material Properties:
Select a suitable material, Structural Steel in this case, and assign its
physical and mechanical properties such as Young’s modulus,
Poisson’s ratio, density, and yield strength. These parameters are
essential for realistic simulation of the spanner’s behaviour under
load.
To Apply Realistic Boundary Conditions and Loads:
Simulate the actual use case by fixing one end of the spanner (to
represent the grip of the user) and applying a force at the other end (to
simulate torque applied during tightening or loosening bolts).
Correctly defining these conditions is critical for accurate results.
To Generate an Optimized Mesh:
Discretize the spanner geometry into small elements using an efficient
meshing strategy that balances computational cost and solution
accuracy. A good mesh is vital for capturing stress concentrations and
deformation patterns.
To Evaluate Structural Responses:
Calculate and study the total deformation, equivalent (von-Mises)
stress, and equivalent elastic strain in the spanner under applied loads.
These results help in identifying the critical areas that experience the
highest stress and potential risk of failure.
To Compare Results Against Material Strength Limits:
Assess whether the maximum stress values remain below the yield
strength of the material to ensure the spanner operates safely without
permanent deformation or failure.
To Understand the Safety and Durability of the Design:
Determine the factor of safety and confirm that the spanner’s design
and material choice meet industrial standards for strength and
reliability.
3. About Spanners
Spanners are indispensable tools in mechanical and engineering
fields, used primarily for gripping and turning nuts, bolts, and other
fasteners. Though they seem straightforward, their design must
address important factors such as ergonomics, strength, and durability.
A spanner is generally composed of a handle and one or more jaws
designed to fit specific fastener shapes, most commonly hexagonal.
The force applied by the user through the handle is transmitted to the
jaw, which then applies torque to the fastener. Different types of
spanners exist, including open-end, box-end, adjustable, and
combination types, each serving specialized purposes depending on
the application and accessibility of the fastener.
The design of a spanner must ensure it can handle the forces applied
during tightening or loosening without undergoing permanent
deformation or failure. This involves selecting appropriate materials
and geometric design to withstand bending and torsional stresses. An
efficient spanner design will not only be strong but also comfortable
to use and resistant to wear. Therefore, understanding the mechanical
behaviour of spanners under load is critical for safety, reliability, and
user efficiency.
4. Applications of Spanners
Spanners are used extensively across various industries and everyday
tasks. In the automotive industry, spanners are essential for engine
assembly, brake maintenance, and other mechanical repairs.
Mechanics use spanners to apply torque to fasteners, ensuring parts
are securely attached. Similarly, in plumbing, spanners help tighten or
loosen pipe fittings and valves, which require precise torque to
prevent leaks. Manufacturing industries rely on spanners for
assembling machines and equipment, where consistent and safe
fastener tightening is crucial for operational safety. In home repair and
maintenance, spanners are common tools used for furniture assembly,
appliance repair, and DIY projects. Because spanners must handle
varying loads and environmental conditions, their design and material
selection must consider durability and resistance to corrosion,
ensuring long-lasting performance in different settings.
5. Introduction to Finite Element Analysis (FEA)
Finite Element Analysis (FEA) is a powerful computational technique
widely used in engineering to predict how structures behave under
various physical conditions. It works by dividing a complex geometry
into smaller, simpler pieces called finite elements. These elements are
connected at nodes, and equations describing the physics of the
problem are solved for each element. The results from all elements are
combined to give a detailed picture of the stresses, strains, and
displacements in the entire structure. This method allows engineers to
analyse complicated shapes and load conditions that would be
difficult or impossible to test physically.
FEA has revolutionized product design and testing by enabling virtual
simulations. It helps identify weak points, optimize material usage,
and improve overall design safety before any physical prototype is
made. For hand tools like spanners, FEA can simulate the effect of
forces applied by users, predicting deformation and stress
concentrations. This reduces the risk of tool failure and enhances
design reliability, making FEA an essential tool in modern mechanical
design.
6. Software Used – ANSYS Workbench
ANSYS Workbench is an advanced simulation software widely
recognized for its robust and versatile finite element analysis
capabilities. It integrates geometry modelling, mesh generation,
solution, and post-processing in one environment. The software
supports multiple physics simulations, including structural, thermal,
fluid flow, and electromagnetic analyses. For this study, ANSYS
Workbench was chosen because of its user-friendly interface, precise
solvers, and extensive material libraries, making it ideal for
simulating the spanner’s structural response.
The imported spanner model is meshed automatically with options for
refinement near stress concentration areas. Material properties for
structural steel are applied, and boundary conditions and loads are
defined to replicate real-world usage. ANSYS then computes
deformation, stresses, and strains, displaying the results visually. The
detailed output helps engineers assess the design and make informed
decisions for improvements if necessary.
7. Geometry of the Spanner
The spanner’s 3D geometry used in this study was modelled using
CAD software and saved in the IGES format for compatibility with
ANSYS. The model replicates a standard box-end spanner, including
the handle and the closed jaw designed to grip hexagonal fasteners
securely. The length of the spanner is approximately 164 mm, with a
width of about 35 mm and thickness around 10 mm, dimensions
typical of a hand tool designed for moderate torque applications.
This precise geometry allows for an accurate representation of how
forces distribute across the tool during use. Particular attention is
given to the jaw area, where stress concentrations are expected due to
direct contact with the fastener. The smooth transitions in the model’s
geometry also help in reducing stress risers that could lead to failure.
8. Importing CAD Model
Importing the CAD geometry into ANSYS Workbench is a critical
step for setting up the simulation. The IGES file format allows
seamless transfer of the spanner model, preserving all its geometric
details. After import, the model is examined to ensure it is free from
defects such as gaps or overlaps that could cause errors during
meshing or solving.
ANSYS provides tools to repair and clean the geometry if needed,
ensuring that the model is watertight and suitable for finite element
meshing. This preparation guarantees the quality of the mesh and the
accuracy of the simulation results, setting a strong foundation for the
entire analysis.
9. Material Selection
Structural steel was selected for the spanner material due to its
favourable mechanical properties, availability, and cost-effectiveness.
Structural steel offers a good balance of strength, ductility, and
toughness, making it a popular choice for hand tools that must
withstand repeated loading and mechanical abuse.
The material properties assigned in ANSYS include a Young’s
modulus of 200GPa, which measures the stiffness of the material, and
a Poisson’s ratio of 0.3, describing its volumetric response to loading.
The density of 7.85 g/cm³ was used for mass and inertia calculations.
Yield strength and ultimate tensile strength were set to 250 MPa and
460 MPa respectively, which help in evaluating safety margins during
analysis. These realistic material values ensure that the simulation
closely represents the actual behaviour of the spanner under load.
10. Meshing
Meshing is the process of dividing the spanner geometry into small
finite elements that form the basis for numerical calculations. An
optimal mesh balances accuracy and computational efficiency. For
this study, a 3D solid mesh with 1048 nodes and 146 elements was
generated.
Adaptive mesh refinement was applied around the jaw area where
high stress gradients were expected. The elements were checked for
shape quality to avoid distorted or poorly shaped elements, which can
reduce solution accuracy. A medium smoothing algorithm was used to
ensure element connectivity and improve mesh quality. This careful
meshing strategy helps capture stress concentrations and deformation
patterns accurately.
11. Boundary Conditions
To simulate real working conditions, one end of the spanner,
representing the handle held by the user, was fixed in all degrees of
freedom. This boundary condition restricts any translation or rotation,
simulating a firm grip. This constraint is crucial to apply the load
realistically on the other end. It ensures the spanner’s response in the
simulation reflects actual usage, where the user’s hand prevents the
handle from moving while force is applied to the jaw.
12. Load Conditions
A downward force of 200 N was applied at the spanner’s jaw,
simulating the torque exerted by a user to turn a bolt. This load
direction and magnitude represent a typical tightening or loosening
scenario.The force was applied as a surface load on the contact faces
of the jaw to distribute the stress realistically. This load application
allows the software to calculate resulting stresses and deformations
throughout the spanner’s structure.
13. Analysis Settings
The analysis type chosen was static structural, focusing on the
spanner’s response to steady load without dynamic effects. The solver
used was the Mechanical APDL solver, which is robust and reliable
for such mechanical simulations.
Temperature effects were not considered since the spanner operates
near room temperature. Small deflections were assumed as the
deformation was expected to be minimal. Convergence criteria were
set to ensure the solution’s accuracy, with iterative steps controlled by
displacement and force residuals.
14. Total Deformation Results
The maximum deformation recorded was approximately 0.126 mm at
the free end of the spanner jaw where the load was applied. This small
deformation confirms the tool’s rigidity and structural integrity.
The deformation gradually decreased toward the fixed handle end,
showing the expected load transfer behaviour. These results indicate
the spanner is unlikely to bend excessively during typical use.
15. Equivalent Stress (von-Mises Stress) Results
The maximum von-Mises stress found was about 44.84 MPa,
primarily localized near the jaw area where bending stress
concentrates. This stress level is well below the structural steel’s yield
strength of 250 MPa, indicating a wide margin of safety. The stress
distribution was smooth, without sudden spikes, demonstrating a
well-designed geometry free of critical stress concentrators.
16. Equivalent Elastic Strain Results
The maximum elastic strain was found to be approximately 2.24 ×
10⁻⁴ mm/mm, a very low value consistent with the elastic behaviour
of steel under normal working loads. This means the spanner returns
to its original shape after the load is removed, with no permanent
deformation.
The strain contours also followed the stress patterns, concentrating
near the loaded jaw and reducing toward the handle.
17. Conclusion
The finite element analysis of the spanner demonstrated that it is
structurally sound under the applied load of 200 N. The deformation
and stress levels are well within safe limits, confirming that the design
and material selection are appropriate.
FEA proved to be a valuable tool in assessing mechanical tool
performance virtually, enabling designers to optimize and validate
designs before physical production. This study supports the continued
use of structural steel for spanners and encourages the use of
simulation in future tool development.