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.
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.
Accurate simulation of golf ball behavior during impact with a club is challenging due to the nonlinear impact event, the complexity of the polymeric ball material at the high strain rates experienced during impact, and the scarcity of material properties at these high strain rates. Veryst Engineering developed an accurate model that accounts for these complexities.
Foam materials often exhibit high strain rate sensitivity, with large increases in stiffness as materials are loaded at higher rates. Veryst performed high-rate compression tests of a foam material, reaching impact strain rates of over 1500/s.
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.
This case study demonstrates the testing and calibration of a polycarbonate material at a high strain rate of 1000 sec-1. The testing was done with the Split Hopkinson Pressure Bar (SHPB) system and the calibration is performed with the MCalibration® software, originally developed by Veryst Engineering.
PEEK materials are increasingly used in a variety of industries with elevated temperature applications. This example shows how Veryst Engineering developed a temperature-dependent, nonlinear model of PEEK behavior for use in commercial FEA codes.
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.
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.
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.