Mid term project Due July 11th

A tensile load passes through the hinge assembly shown below. A pin, surrounded by titanium bushings is
used to make the connection between two components. Your client has provided you with a simplified
CAD model (in mm) of the arm only, which doesn’t include the fillets, bushings or pin. Your goal is to
determine the factor of safety for the arm, assuming that the failure mode is considered to be yielding of
the material. The bushings are titanium (E = 112GPa, ν = 0.34, bearing yield stress =1480MPa) and the
arm material is listed according to your names. Properly site your literature source for the material
properties of the arm.

The simplified geometry provided to you is shown below. You should first run a preliminary analysis
without the bushings and fillets and then compare the results with bushings and fillets included, stress
concentration and value is expected to vary. Assume any missed geometry.
 Student name Tensile Arm Arm length Arm width Arm Face height Face
load (kN) material (mm) (mm) thickness (mm) length
(mm) (mm)
Adugnaw Assaye 120 Aluminum 500 250 250 350 500
Destaye Dessalegn 110 Steel 450 300 300 400 450
Fissha Muche 100 Stainless 400 350 350 450 400
steel
Araya Mahtem 90 Copper 350 250 250 350 350
Assmamaw 90 Aluminum 350 300 300 400 350
kassaw
Bayou muche 100 Steel 400 350 350 450 400
Yesuf Mohammed 110 Stainless 450 250 250 350 450
steel
Eyerusalem Asfaw 120 Copper 500 300 300 400 500
Addisalem Maru 120 Aluminum 450 350 350 450 450
Zelalem Aychew 90 Steel 400 300 300 400 400
Adualem mulugeta 110 Stainless 350 350 350 450 350
steel
Estifanos Yibabie 100 Copper 450 250 250 350 450
Anwar Jemal 120 Aluminum 400 250 250 350 400
Agidew Amsalu 130 Steel 350 350 350 450 350

Assumptions: -

• A contact model is not required. Assume that the other component and the pin exert the given load
as bearing load on the arm holes instead of using contact between the parts. You should explain
why this assumption is valid.
• You only need to consider the given load along the longitudinal axis of the hinge assembly
(horizontal) and you don’t need to worry about the hinge rotating to different angles.
 • Assume that the pin does not bend, ie. there is no moment between the pin and the bushings.
Because of this, you can apply a boundary condition to the inside of the arm that prevents the
flanges from moving inwards.

• The titanium bushings are 3mm thick (inner and outer diameters of 19mm and 25mm respectively)
and fit tightly inside the holes in the arm. It can be assumed that the bushings are “glued” to the
hole in the hinge.
• Assume that the pin fills the bushings.

Deliverables:-
• A detailed lab report following the guidelines in the document “Report Requirements”.
• An overall description of any preliminary models.
• A description of the final model including a screenshot of the final mesh size that you think
produces accurate results.
• A well constructed mesh that incorporates local sizing
• A convergence study and associated plot of the critical region in the arm.
• Include screen shots illustrating the largest and smallest mesh sizes that were considered.
• The maximum stresses for the critical regions in the arm and the resulting factors of safety.
• Include images of the overall results, a hand calculation verifying the stress results anywhere in
the model, and discuss the overall response of the arm.
Formal Lab Project Report Requirements:
In general lab/project reports should be clear, concise, and neatly presented with no typos or grammar
mistakes. Reports showing links between classroom theory and practice as well as in depth discussions
will be rewarded. Reports should follow the overall outline shown below.
Introduction/Problem Description

• A description of the physical problem ie. what does the assembly do, how does it physically work,
how does it interact with other components, how it is loaded. You have to assume the reader does
not know anything about the assembly.
• The description may include a picture or sketch of the physical structure with a coordinate system
shown.
• Explain the purpose of the model ie. what are you hoping to achieve by performing a finite element
analysis?

Model Description
- This section describes the model that was created and should be in enough detail that a reader would
be able to understand all the steps involved in the analysis (without including commands). Any
assumptions that were made when representing the physical structure should be clearly stated in
the appropriate section (ie. the ground was represented by a fixed boundary condition, the contact
between the two parts was represented by a pressure of XX, the wood was assumed to be isotropic
as knots and the grain direction was not considered…)
o Overall approach
▪ What parts of the assembly are you including
▪ Are you performing a linear or non-linear analysis and why
▪ Are there any major assumptions you are making (ie. in reality it is a dynamic problem,
but the model is of a point in time where static equilibrium is being assumed)
o Geometry
▪ State the dimension of the model (ie. Line, planar or solid model)
▪ Describe any geometric simplification from the physical structure (ie. what parts were
considered and what was ignored, fillets not modeled …).
▪ Either include a dimensioned drawing, or a sketch/picture with the key dimensions
mentioned in the text. The reader should know what the overall size of the component
is.
o Material Properties
▪ what is the material (ie. AA5754 aluminum alloy)
▪ what material model was used and why (ie. linear isotropic…)
▪ values of the material properties (ie. E = 70GPa)
o Element Type and Mesh
▪ State the element shape and order used (ie. higher order brick elements)
▪ Include a plot of the mesh, along with a description and its specifications (ie. a sweep
mesh of brick elements with a size of 0.5mm was used in the web of the structure,
while tetrahedral elements with a global size of 0.1mm were used in the end regions…)
o Loading and Boundary Conditions
 ▪ State the values and directions of any loads and boundary conditions (ie. the face on
the inside of the bolt hole was constrained in the X, Y and Z directions).
▪ Clearly explain any assumptions or simplifications (ie. contact between the two
components was not included, rather a pressure representing the contact force was
applied to the end face)
▪ If the loading in unconventional ie. bearing load, explain the details of how it works.
o Solution
▪ State whether the analysis is linear or non-linear.
▪ State any defined solution parameters (ie. 1 loadstep was used)

Model Results
- Only the required results are presented and you should not include any unnecessary figures that are
not referenced or discussed. It is up to you to decide how to best present these results and they
could be in the form of contour plots, probed results or tables. Results typically presented are:
o Overall description of the component behavior. (ie. the applied moment caused the component
to twist about its longitudinal axis and vertical deflection was also seen at the free end). This is
required.
o Contour plots and descriptions of the applicable results such as stress results, deflections or
deformed shape for the overall model or at specified locations.
o State the value and the location of maximum stresses and displacements.
o Identify any unrealistic results (ie. the stresses around the bolt holes are not realistic as they
were constrained in all directions instead of being modeled in contact with the bolts).

Discussion
- This section will include a discussion of the results and will show a validation of why you think the
model results are correct.
o Discuss whether the results make sense (ie. does the structure deform as expected, are the
highest stresses in the expected locations, does the stress distribution appear correct?)
o Show a hand calculation or some form of validation and comment on the comparison with the
model predictions.
o Any requested studies are discussed such as a convergence study or design study.
o List any applicable sources of error.
o Discuss the limitations of the model, how could it have been improved.
o Answer any questions that have been asked

Reference and formatting