Case study

FEA of Absorbable PLLA Bone Screw
The nonlinear deformation and material relaxation associated with modeling the polymer screws for anterior cruciate ligament (ACL) reconstruction makes predicting key quantities such as stresses and holding forces challenging. Veryst, with its unique ability to test and model PLLA materials, was able to develop material and finite element models that predict the important short-term pull-out forces as well as the evolution of stresses over time.
FTIR Microscopy Analysis of Thermoplastic Solvent Bonding
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.
Guidewire Entanglement
Guidewires and stents can become entangled during deployment. Veryst assisted in determining whether product design plays any role in these events.
High Rate Temperature Response of Polymers
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.
High Strain Rate Testing of Fiber-Reinforced Thermoplastics
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.
Impact Fracture Toughness of Adhesive Joints
Veryst developed a new test method for measuring fracture toughness under impact loading that does not require measurement of load or crack length. We have used this method to help clients in the automotive and electronics industry understand how adhesives fail under impact conditions.
Insufflation Analysis
To compare the performance of two gas humidification devices, Veryst Engineering performed gas flow testing, device examination, and CFD analysis.
Osteotome Fracture
An osteotome unexpectedly failed during a plastic surgery operation. Veryst was hired to explain the failure.
PEEK Temperature Dependence
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.
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.
Plastic Clip Failure
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 Foam Testing & Modeling
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.
Polymer Forming Simulation
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.
Polymer Material Models in Different FE Packages
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.
Real-Time Monitoring of Adhesive Curing and Kinetic Model Calibration
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.

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