A plastic clip used to retain a patient support failed, resulting in an occupant death. Veryst was asked to determine the cause of failure.
Polymer foams may exhibit extreme strain rate-dependence due to their structure. The low stiffness means testing the materials at high strain rates is particularly difficult. Veryst has developed multiple test methods to test and model these materials.
Obtaining accurate results from finite element analyses of polymers is not easy. Polymers are often highly temperature- and rate-dependent, exhibiting significant stress-relaxation, creep, and recovery. In this forming case study, Veryst examines the steps required to produce an accurate constitutive model of an example polymer, polyether ether ketone (PEEK), and shows the consequences of oversimplification.
All commercial FE packages provide material models for polymers, but Veryst Engineering’s PolyUMod® material library has advanced material models at the leading edge of polymer mechanics. We demonstrate the accuracy of a PolyUMod material model with native material models from Abaqus, ANSYS, and LS-DYNA.
Designing an assembly process using a thermoset adhesive can be challenging without an understanding of the adhesive curing kinetics. Veryst engineers use FTIR spectroscopy to analyze curing and optimize processing steps.
Materials that have been deformed past their yield point and into the plastic strain region often display permanent deformation upon removal of load. How much of this deformation is truly permanent? Veryst has developed a method to measure the residual strain of materials following unloading as a function of time.
Shear thickening and jamming in dense particulate suspensions can lead to undesirable processing inefficiencies and failure modes across a variety of product applications, including inkjet printer nozzles, medical autoinjectors, and porous filtration systems. In this case study, Veryst simulated the flow of a dense suspension through a syringe needle to evaluate the conditions that lead to shear jamming.
Knowledge of thin film mechanical properties is important for device operation, reliability, and simulation. Veryst measured the elastic modulus of a low stress silicon nitride thin film using nanoindentation and validated the technique with atomic force microscopy.
Medical devices, combination products, consumer products, and manufacturing processes often include components that slide past each other. These products and processes can fail when the friction forces between the surfaces are too high, due to surface roughness, lubrication, materials, or environmental conditions. Here Veryst introduces a specialized fixture to measure the friction between a small metal wire and three polymer materials, to select a backup supplier for dual sourcing that would maintain low friction in a medical device.
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.
Tempered and plate glass are manufactured to produce very different fracture patterns when they break. Veryst can use this information to identify installed glass products and discuss the implications of their use.
Shape memory alloys, like nickel titanium alloy (nitinol), are common in medical device applications. Nitinol is often used in fine wire form and can be difficult to test. Veryst has developed methods to test fine nitinol wires in uniaxial tension at different temperatures to obtain a stress-strain curve.
The material properties of a climbing shoe’s outsole rubber directly affect a rock climber’s performance. Veryst performed friction and compression testing of two climbing shoe rubbers to quantify and compare their performance.
Many engineering applications require understanding the behavior of polymers under cryogenic temperature conditions. Veryst developed a test fixture and method to test materials submerged in liquid nitrogen (LN2) at its boiling temperature of -196°C.
Veryst assists clients with the selection of adhesive materials, development of bonding processes, and mechanical analysis of interfaces. We employ chemical characterization, mechanical testing, and advanced computational methods to design robust adhesively bonded structures and to understand delamination failures.