Stress Evolution of Amorphous Thermoplastic Plate during Forming Process

Area of Science:

• Materials Science
• Polymer Engineering
• Computational Mechanics

Background:

• Amorphous thermoplastics are vital engineering materials requiring process optimization for high-performance products.
• Residual stresses in thermoplastic plates are critical for product quality but challenging to measure directly.

Purpose of the Study:

• To model and analyze the residual stress evolution during the forming of polyetherimide (PEI) plates.
• To validate the finite element analysis (FEA) model with experimental warpage data.

Main Methods:

• Finite Element Analysis (FEA) was employed to simulate the PEI plate forming process.
• Experimental validation was conducted by comparing simulation results with warpage measurements.

Main Results:

• The forming process was segmented into three stages relative to the glass transition temperature (Tg) of PEI.
• Cooling from above Tg to below Tg (the second stage) is a major contributor to residual stress development.
• Residual stress distribution through the plate thickness follows a parabolic pattern.

Conclusions:

• Cooling rate and plate thickness are key factors influencing the final residual stress magnitude.
• Understanding these stress dynamics aids in enhancing amorphous thermoplastic plate quality and production efficiency.