Thermoelastic and Creep Analysis of a Reinforced Plastic Interrupter Shell Assembly

Abstract

In the present paper an interrupter shell assembly that forms an essential part of electrical switch gears is considered for creep analysis and subjected to thermal loads in addition to static leads actuated by circuit breakers. This exercise forms a part of the design evaluation of a new product. The shell is made out of a high strength fiberglass reinforced thermoset polyester sheet molding compound. A conventional finite element formulation based on the classical theory of semicoupled thermoelasticity is employed. The creep phenomenon is considered as an initial strain problem and a time hardening law is followed for creep analysis in the secondary zone. The structure is discretized by bilinear thick and thin flat shell isoparametric elements. Results show the contrasting deformation patterns, creep and thermomechanical stresses with the strains for two temperature cases. Creep characteristics of the shell are depicted for the entire service life of the component.

Tensile creep of thermoplastics: Time‐strain superposition of non‐iso free‐volume data

“…Nonlinear creep behavior of polypropylene was found2, 33 to obey a relatively simple equation where W (σ) is a function of stress, and 0 ≤ n ≤ 1 is a constant independent of elapsed time and applied stress. Isothermal nonlinear creep of polymers was also plausibly fitted24, 38–41 by the power law where m ≥ 1 ( m = 1 in the region of the linear stress‐strain relationship) and 0 ≤ n ≤ 1.…”