3D Mechanical contact and elastic-plastic analysis
Challenge and Ambition
FOSS uses a diamond-based sealing between a cuvette and a retainer ring in a liquid analysis instrument. The system should be designed so that:
- The sealing remains closed during thermal cycling, where differences in the thermal expansion of the components can result in leakage.
- The stress state in the diamond sealing does not induce fracture.
To achieve this the cuvette-holder geometry and material can be changed.
Solution
To accurately capture the behavior at the diamond-to-cuvette-holder interface, an FEA analysis in COMSOL Multiphysics is carried out, observing the following:
- The diamond-to-cuvette-holder interface can change status (go in and out of contact) during a thermal cycle – thus the analysis must include a contact formulation.
- The cuvette holder will yield locally in the contact region, and this will in turn affect contact pressure, thus the analysis must account for plastic yielding.
- The cuvette-holder can undergo deformation leading to ovalization, thus a 3d analysis accounting for the full structure is needed.
- The analysis is carried out for several candidates for cuvette-holder material, the geometry is parameterized, and a combination that fulfills the requirements is chosen.
The simulation work saved a large number of expensive prototypes otherwise needed to find the optimal design. It also promoted an in-depth understanding of the system used for later design modifications.
Customer: FOSS Analytics
Industry: Food tech
Discipline: Structural Mechanical
