Polymer Mechanics

Accelerated Creep Testing of Polymers with Time-Temperature Superposition

A medical device designer wanted to forecast the creep performance of a plastic part for at least two years. Veryst tested the material using time-temperature superposition to characterize the material’s long-term performance quickly and efficiently to determine if the design performs adequately after two years.

Additively Manufactured Lattices

Additive manufacturing (AM) enables the production of complex lattice structures that cannot feasibly or economically be manufactured any other way. However, there are complicating factors that engineers are likely to confront when designing fine AM lattice structures: geometric inaccuracy and anisotropic material properties.

Anisotropy of 3D-Printed Polymers

Many additively manufactured polymers exhibit anisotropic mechanical properties which must be accounted for by engineers designing with these materials. This case study illustrates the importance of testing additively manufactured polymers at many orientations to identify the range of isotropic behavior as well as the optimal build orientation.

Fatigue Failure of a Plastic Lever

A plastic lever on a consumer product failed unexpectedly in service. Veryst determined the root cause of the failure and provided design recommendations to prevent similar failures from occurring again.

Peeling of a Soft Polymer Film

The peel test is widely used to measure the adhesion of thin, compliant films to rigid substrates. An accurate model of the peeling mechanics is required to extract the interface adhesion energy. Veryst used the PolyUMod® material model library along with a cohesive zone model of interface adhesion to simulate the peeling of a soft viscoplastic film from a rigid substrate.

Strength of Additively Manufactured Parts

Veryst can predict the ultimate strength and failure modes of design concepts generated using topology optimization and produced using additive manufacturing. We use advanced finite element analysis (FEA) that accounts for the nonlinear behavior of the material being used to make the part.

Publication in Materials and Design journal

Dr. Jorgen Bergstrom has co-authored a paper titled "Mechanical properties of 3D printed polymeric cellular materials with triply periodic minimal surface architectures" published in the journal Materials and Design (Vol. 122, 2017).

Publication: Veryst develops advanced constitutive model for UHMWPE

Ultra-high molecular weight polyethylene (UHMWPE) is used extensively in biomedical devices due to its mechanical properties, including high impact and wear resistance. Veryst developed an advanced thermomechanical constitutive model for UHWMPE where the microstructure of the material is represented using three structural domains that capture the experimentally-observed, nonlinear, time- and temperature-dependent response at small and large strains.