Product Liability Expert Witnesses for Defective Plastic Products

FEA (Finite Element Analysis) models stress distribution throughout a plastic part to determine whether the design evenly distributes loads or concentrates them at weak points. Wrong material selection for service requirements (heat exposure, chemical environment, UV radiation) is a common cause of premature failure. Parts must be designed to account for both mechanical stress patterns and mold fill patterns, because knit lines from the molding process create weak points that interact with service stresses.

CT scans reveal voids near surfaces where cracks initiate, incompletely fused knit lines, and other internal defects invisible from outside. Molding conditions must be optimized and maintained throughout production: temperature, pressure, cooling rate, and cycle time all affect part quality. Contaminated resin is a serious issue: in one case, a folding step stool made in China contained foreign PVC particles embedded in what should have been pure polypropylene (PP). Chemical analysis confirmed the PVC contamination weakened the material's strength.

SEM reveals the fracture mode (environmental stress cracking (ESC), tensile overload, fatigue, creep, or high-speed impact), each of which leaves distinctive 'tell-tale marks' on the fracture surface traceable to the crack origin. Chemical incompatibility is a critical failure mechanism: amorphous plastics like polycarbonate (PC) are vulnerable to hydrocarbon chemicals, while crystalline plastics like polypropylene (PP) resist them. The classic example is Tupperware: made from PP, it resists nearly all household chemicals. But a PC water bottle exposed to the wrong cleaning chemical can crack catastrophically. ABS drain traps exposed to acetone-based drain cleaners fail the same way.

We evaluate whether a product was used as intended, maintained as instructed, or subjected to conditions or forces beyond its labeled specifications. In medical-device cases, this can include patient or caregiver handling that departs from the instructions for use, off-label application, or improper cleaning and sterilization outside manufacturer protocols. In consumer and industrial cases, it can include modification, overloading, or continued use after visible damage. Our methodology applies the same objective standard regardless of which side retains us: SEM fractography, FTIR chemical analysis, and CT scanning identify the physical evidence of overload, contamination, or wear patterns consistent with misuse, and we report what the evidence shows even when it does not support the retaining party's position.