CAE Engineering Optimization Case Studies

CAE Engineering Optimization - Crossmember

CAE Engineering Optimization - Crossmember

Background and Objective
Back-of-cab crossmember was found to develop cracks during durability testing.

Results - Baseline
Maximum von Mises stress of 754 MPa was observed during FE simulation.

Stress areas above yield of the material correlated with areas where the cracks formed during durability testing.

Design Optimization - Proposal I
Topology optimization resulted in design shown.

Stress analysis resulted in a maximum von Mises stress of 633 MPa.

Design Optimization - Proposal II
New design space defined.

Stress analysis resulted in a maximum von Mises stress of 427 MPa.

Summary of Results

CAE Engineering Optimization - Engine Front Cover

CAE Engineering Optimization - Engine Front Cover

The first frequency of the first mode was found to be low - 388 Hz. The low first mode caused noise and vibration issues. With the development of production parts frozen, the only feasible solution was the addition of ribs. Therefore, it was decided to perform an Engine Cover Design Sensitivity Analysis to identify optimal rib locations to increase the first modal frequency of the part.

Modification Proposed by Design Team
The design team at our customers location recommended adding ribs in the locations illustrated in the picture below. Addition of the ribs resulted in an increase in the first modal frequency from 388 Hz. To 584 Hz. which did not meet the design requirement.
Design Space Definition
Optimal along with the customer, defined all possible locations where ribs could be added. A Design Sensitivity Analysis was then performed to identify critical rib locations.

DSA and Optimization Results
Results from the DSA and optimization analysis identified critical rib locations. Ribs that are color coded black were found to be ineffective.

Optimal's Proposed Design

Results - Proposed Design
Using the proposed design, the first mode increased from 382 Hz. To 1204 Hz. This exceeded the design target. Additionally the second and third modes also benefited by the proposed ribs.

CAE Engineering Optimization - Motor Holder

CAE Engineering Optimization - Motor Holder

During laboratory testing, noise that was identified as the excitation of the motor at the 12th harmonic was observed. Optimal was asked to re-design the motor holder to reduce the noise generated.

Baseline Correlation Model Analysis
A finite element analysis was performed on the baseline model. The analysis resulted in the extraction of several modes. The first mode was found to be at 60 Hz. and the analysis correlated with the laboratory test. The torsional mode was obtained at 204 Hz.

Topology Optimization Model
In order to conduct a topology optimization, the design space was first designed. The space between the motor and the holder was filled with solid elements.

Results & Proposed Design
The topology optimization runs resulted in a honeycomb structure for the motor holder. The baseline finite element model was then updated to reflect the optimization results.

Results - Proposed Design
The final modal analysis gave the following results:

  • First mode increased from 60 Hz. to 269 Hz.
  • The torsional mode increased from 204 hz. to 695 Hz.
The increase in natural frequencies resulted in the elimination of the noise.

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