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.
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.
An adhesive joint was failing in the field. Veryst used DSC to investigate and determined the root cause to be improper curing of the adhesive.
Joining polyolefins such as polyethylene and polypropylene with adhesives can be challenging. Polyolefins have low surface energy, which creates weak bonds between the polyolefin material and the adhesive. Veryst used corona discharge plasma treatment to improve the bond strength and create a more robust joint.
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.
Bioabsorbable materials, such as polylactic acid (PLA), are finding increasing applications in medical devices. These polymers exhibit a nonlinear anisotropic viscoplastic response when deformed, which requires a sophisticated material model for accurate finite element predictions.
Cohesive zone modeling is a powerful tool for predicting delamination in adhesively bonded structures. Veryst engineers use their expertise in experimental and computational fracture mechanics to calibrate cohesive zone models for accurate prediction of adhesive failure.
Composite materials, such as carbon fiber reinforced polymers, provide a high strength-to-weight ratio for structures ranging from aerospace components to biomedical implants to consumer sports products. These materials require thorough and specialized methods for material testing and validation due to their anisotropic material properties.
Polymers are prone to deform slowly over long periods of time when subjected to applied load, a phenomenon known as creep. Over time, the deformation can grow so large that the part no longer functions as intended. Veryst utilized creep testing to compare material choices and set temperature specifications for polymers.
A high-strength reinforced hose failed in service under normal operating conditions well before its intended design life. Inspections of the subject hose revealed that failure was mainly due to delamination.
Elastomer foams make excellent vibration dampers, but accurately designing these dampers requires an advanced material model. Veryst calibrated a PolyUMod® material model to design the vibration damper.
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.
Solvent bonding, although an effective way to join thermoplastics, can pose process challenges that reduce bond strength. Veryst uses FTIR microscopy to characterize the interface structure of solvent bonds, obtaining a “chemical image” of the solvent-bonded interface. The result is a full understanding of the bond and ways to improve its strength and reliability.
Polymers exhibit significant temperature-dependent mechanical response. Veryst tested a PEEK material at multiple temperatures and calibrated the PolyUMod® Three Network (TN) material model for finite element simulation.
Understanding composite materials’ impact response as a function of fiber direction is important for a wide range of uses, from automotive applications for crashworthiness to consumer product uses for drop and impact resistance. Veryst evaluated the high strain rate response of both glass fiber and carbon fiber reinforced PEEK (polyether ether ketone) using the Split Hopkinson Pressure Bar test method.