Charles Weaver's Research

Biography:

Charles Weaver

Research:

"Currently, industry standards for pallet load stability, such as EUMOS 40509, specify a standardized dynamic test profile to certify that a stretch-wrapped unit load will withstand transport without unacceptable deformation. The standard prescribes a fixed trapezoidal acceleration pulse and specifies allowable elastic and permanent deformation limits; however, recent field research has shown that this prescribed pulse does not reflect actual truck braking conditions. When calibrated to match real-world braking severity, the standard test has been shown to overestimate load deformation by 70% to 150% compared to field-measured events, suggesting current testing practices may be driving unnecessary overuse of stretch film and other load stabilizers.

A physics-based model exists (Matyja’s N-layer model) capable of predicting how a stretch-wrapped, layered unit load deforms during braking by accounting for interlayer Stribeck friction and the restoring force of the stretch film. This model has only been evaluated against synthetic, EUMOS-style braking pulses and has never been validated against measured field data — a gap that limits its usefulness for revising current testing standards.

For these reasons, this project is focused on validating the Matyja model against real-world field braking events and applying the validated model to establish a physics-grounded basis for revising laboratory test profiles. We are developing a physical unit load avatar and independently characterizing the mechanical parameters the model requires — interlayer friction and breakaway velocity, stretch film stiffness, and initial containment force. Once these parameters are established, the avatar will be subjected to controlled braking events in a box truck to obtain field deformation data and the corresponding vehicle deceleration profile, which together will serve as the model’s validation input. We will also evaluate the current EUMOS 40509 profile against these benchmarks to characterize the extent and consistency of its overestimation across varying friction conditions. With these results, the validated model will be used to computationally map laboratory-executable test profiles capable of reproducing field-realistic deformation.

The goals for summer 2026 are to finalize the mechanical characterization protocols and physical construction of the unit load avatar, and to complete independent measurement of the governing model parameters."