FEA Analysis to Enhancing Stiffness & Fatigue Life of Rubber-to-Metal Bonded Parts

Project Overview

Bony Polymers, a trusted manufacturer of precision rubber-to-metal bonded parts in India, approached us to improve the performance of a critical side bumper assembly. The goal was to increase the component's static stiffness to 0.7 kN/mm for a displacement range of 5–10 mm, while also ensuring that the part could reliably withstand at least 600,000 load cycles.

The application demanded not just mechanical integrity, but also longevity under fatigue, especially given the repeated stress such components experience in real-world use. Our task was to use finite element analysis (FEA) and material modeling to evaluate, refine, and validate a design that could meet both mechanical stiffness and durability targets.

The Challenge

The initial version of the side bumper exhibited suboptimal stiffness and unclear fatigue behaviour. While the basic geometry and material selection were in place, there was a lack of clarity on whether the part could meet the required mechanical response within the allowed deformation limits or survive long-term cyclic loads.

The specific challenges included:

Achieving a static stiffness of 0.7 kN/mm between 5 mm and 10 mm deflection
Ensuring consistent load response across a broad force range (up to 18 kN)
Modeling complex rubber behavior accurately
Validating that the component could withstand 600,000 fatigue cycles, especially in high-strain zones

It became clear that a deep dive into hyperelastic material modeling, fatigue simulation, and load path optimization was necessary to meet these targets.

Our Solution

We began by reviewing the initial simulation model and identified several areas for refinement. These included boundary conditions, material definitions, and how loads were applied. After cleaning up the setup, we modified the geometry to better distribute stresses and reduce peak strain zones.

Advanced FEA Modeling

The updated simulation model was built in ANSYS, and it included:

Fixing inaccuracies in the initial geometry setup
Applying realistic boundary conditions (fixed face and precise load application)
Assigning the correct elastic modulus (12.4 MPa) for the bottom rubber plate

To capture the true non-linear response of rubber, we introduced hyperelastic material models, including Neo-Hookean and Marlow, both of which are better suited for elastomeric simulations than traditional linear elastic assumptions.

Stiffness Evaluation

We conducted multiple FEA iterations to optimize the design. A key outcome was when a 7 kN force produced exactly 10 mm of deformation, confirming that the stiffness had reached:

7 kN / 10 mm = 0.7 kN/mm

This value met the exact target set by the client.

We also extended the load range to verify behavior under higher forces. Simulations ran up to 18 kN, showing deformation behavior stayed within safe limits without overstressing any region of the part.

Fatigue & Durability Analysis

Fatigue simulation was then performed using ANSYS. The fatigue load was set at 18 kN, representing a conservative estimate of operational stress. The analysis revealed:

The main load-bearing rubber areas exceeded the 600,000-cycle requirement
Localized areas near the edges of the bottom plate had a lower life (~170,000 cycles), but these regions primarily serve damping functions, not structural roles, and thus did not compromise the functionality

Final Reporting & Approval

We compiled all results, including:

Stress and deformation plots at various load levels
Fatigue life maps
Graphs showing deformation versus force
A stiffness curve confirming mechanical targets

The complete report was shared with Bony Polymers, who reviewed the solution and officially approved the final design for production use.

Results & Benefits

This project resulted in a robust, validated solution that:

Achieved 0.7 kN/mm stiffness precisely within the target deflection range
Demonstrated stable deformation behavior across a wide loading spectrum
Surpassed the 600,000-cycle fatigue durability requirement
Maintained performance even under worst-case loading (18 kN)
Minimized stress concentrations through design optimization

The integration of hyperelastic modeling made the predictions much more reliable, reducing the need for excessive physical prototyping and helping the client accelerate their design-to-approval timeline.

Conclusion

For Bony Polymers, this project validated that simulation driven design can deliver real-world performance. Through a strategic blend of advanced FEA techniques, realistic material modeling and fatigue simulation, we were able to exceed both mechanical and durability expectations.

The new side bumper design is now approved for use, and the process helped reduce development cost, improve confidence in long-term reliability, and ensure compliance with the application's demanding performance criteria.

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What Our Clients Says

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