FEA SEEMS TO BE LINING UP WITH MY CALCS! In the right range!
Sharp corners are likely to have the highest stresses. This was also observed by fixing the hole surface of the rod end hole; the pointed edge of the hole had the highest stress in that case.
Filleting seems to be good
Bend doesn’t affect it a lot
The mesh doesn’t need to be crazy small
It’s okay if it’s not like the previous steering arm, since our loading case is different
Why are our loading conditions so different from MSXII’s?
What happens when you make it thinner and taller? This increases moment of inertia; is it better for torsion? Test this tomorrow
How does it work without any fillets? Test this tomorrow
11/05/19
Max stress = 233.59 MPa
Max deformation = 0.84289 mm
Making the arm thinner was an okay idea
Refining mesh made results more predictable
Filleting isn't crucial
Our culprit is not the rod end hole, but the steering bracket hole
MESH CONVERGENCE WAS NOT TESTED and this needs to be done tomorrow!
Can we add weight reduction slots? Is it better on the top, bottom, left, or right sides?
Should the wall thickness change around the steering bracket hole? Maybe the shape shouldn't be so rectangular there? Look into other shapes.
11/07/19
Max stress = 293.7 MPa
Max deformation = 1.1682 mm
Started looking into convergence. Dilemma: the Mesh Numbering object must be used to allow Ansys to recognize that the 32k nodes (max number of nodes for student version) hasn't been reached, BUT you can't use Mesh Numbering with the automatic convergence object. It's just not allowed
We might wanna make the end that attaches to the steering bracket even beefier. But the steering bracket is to be changed soon so the contact points will likely be changed as well.
Going forward, there definitely are stress concentrations at edges. Deal with this by filleting and removing/filleting the bend in the arm. The bend doesn't need to be so prominent. Brainstorm a more creative way to get flat surface at steering bracket end without the stress concentration in the bend
Should the end attached to the steering bracket end be beefier? Is that normal?
What is the maximum acceptable deflection?
11/08/19
Max stress = 361.68 MPa
Max deformation = 1.7686 mm
The end of the steering arm was changed to be a clevis end. It's failing at the edge of the hole in the clevis end.
The clevis end should be thicker. To accommodate for this, extra material can be removed in the middle (i.e. the side profile should look tapered, not like a rectangle so much anymore)
How do different rod end thread sizes (i.e. hole sizes) impact the stress?? TEST THIS WITH SEVERAL GEOMETRIES! Try M10, M12, M14, M16 tomorrow
11/24/19
Max stress = 99.646 MPa
Max deformation = 0.0064676 mm
Min safety factor = 2.5089
NEW LOADING CASE is way more realistic
Loading calculations in google sheet seem accurate except for at stress concentrations
Steering arm is likely overbuilt but that is okay for DFM, also for load cases we haven't considered
12/05/2019
Max stress = 179.83 MPa
Max deformation = 0.29162 mm
Min safety factor = 2.4467
geometry got changed so steering arm is now raised towards the front of the car
most dimensions remained the same, some changed to allow stuff to fit better
Version 1: 4 mm clevis wall thickness, 20 mm height as upright mount point end
Max stress = 106.47 MPa
Max deformation = 0.17873 mm
Min Safety factor = 4.1328
Mesh convergence = 3.7142%
Version 2: 3 mm clevis wall thickness, 16 mm height as upright mount point end
Max stress = 155.05 MPa
Max deformation = 0.23124 mm
Min Safety factor = 2.8379
Mesh convergence = 2.1453%
A slot was added at the end to remove need for a washer
A 3 mm thickness at the clevis end passed (SF = 2.1453 > 2), but this seems too thin. MSXII has a thickness of 6 mm
It may be worth it to combine aspects from both versions: 4 mm wall thickness and 16 mm height at upright mount end
Add slots so that material is minimized in the center of the steering arm, similar to MSXII.
Look into other cuts which could reduce the weight of the part
Version 1: 5 mm clevis wall thickness, 4mm deep straight slots on either side
Max stress = 90.166 MPa
Max deformation = 0.15161 mm
Min Safety factor = 4.8799
Mesh convergence = 4.2974%
Version 2: 5 mm clevis wall thickness, 5 mm deep triangular slots on either side
Max stress = 90.607 MPa
Max deformation = 0.15431 mm
Min Safety factor = 4.8562
Mesh convergence = 3.2009%
Clevis wall thickness was changed as 3mm is a risk. MSXII used a wall thickness of 6 mm. 5mm seems to be a reasonable amount since the safety factor is the lowest at the clevis end, and both cases yielded a safety factor greater than necessary.
Changing the slot dimensions did not change the Von Mises stress. As the loading on the steering arm will change during travel, it may not be a good idea to increase the slot depth. At a slot depth of 5 mm, the minimum distance between slot faces is 10.4 mm.
Discuss slot depth with other steering members
Version 1: extruded cut through all, 5mm wall thickness
Max stress = 175.74 MPa
Max deformation = 0.68664 mm
Min Safety Factor = 2.8621
Version 2: extruded cut through all, 6mm wall thickness, R3.28mm fillet inside cut
Max stress = 128.87 MPa
Max deformation = 0.46128 mm
Min Safety Factor = 3.9336
Version 2: extruded cut through all, 5.5mm wall thickness, R3.5mm fillet inside cut
Max stress = 151.55 MPa
Max deformation = 0.55678 mm
Min Safety Factor = 3.3189
The design was changed to be more rectangular for DFM
Version 1 failed; SF>=3 is required
Version 2 is more manufacturable; the radius of the cut * 5 = the height of the section. It is 3.28 mm. This should be changed to a larger standard radius in V3. change it to 4 mm
V3 has a wall thickness of 5.5 mm because 6 mm caused the steering arm to be overbuilt
