Characterization of Residual Stresses in Composite Parts Manufactured by Material Extrusion Technology Using Reflection Photoelasticity

TL;DR

This paper explores using reflection photoelasticity to visualize and compare residual stress relaxation in 3D-printed composite parts made with aramid fiber-reinforced ASA.

Contribution

The study introduces a practical method combining abrasive water jet cuts and reflection photoelasticity for full-field residual stress analysis in FFF composites.

Findings

Reflection photoelasticity effectively visualizes residual stress relaxation in 8–10 mm thick FFF composite samples.

Annealing significantly reduces global maximum fringe orders in thicker samples.

AWJ relief cuts provide a repeatable stress-release method with minimal thermal impact.

Abstract

Residual stresses are a persistent challenge in the additive manufacturing of composite parts by FFF (Fused Filament Fabrication) and can impair dimensional accuracy and mechanical performance. This article evaluates reflection photoelasticity (PhotoStress) as a full-field optical technique to visualize and compare residual-stress relaxation in ASA (Acrylonitrile Styrene Acrylate) reinforced with aramid fibers. The approach combines a controlled AWJ (Abrasive Water Jet) relief cut to induce local stress release with subsequent optical recording of isochromatic fringe fields using a reflection polariscope. Samples with thicknesses of 2–10 mm were manufactured and evaluated in two conditions: non-annealed and after annealing (80 °C/5 h). Under identical optical settings, no discernible isochromatic fringes were detected for 2–6 mm (Nmaxlobal < 0.60 in both conditions), whereas resolvable fringe patterns were observed for 8–10 mm. For 8 mm, the response was localized near the relief cut, with Nmax,global = 1.0 in the non-annealed condition and Nmax,global < 0.60 after annealing. For 10 mm, the response was more spatially extensive, and annealing reduced the global maximum from Nmax,global = 1.2 to 0.9. Taken together, these results demonstrate that reflection photoelasticity supports comparative full-field visualization of residual-stress relaxation in FFF composite specimens under fixed measurement conditions. In addition, an AWJ relief cut constitutes a practical and repeatable stress-release feature with limited additional thermal influence in the present configuration.

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