Analyzing the long-term creep behavior of composite pipes: Developing an alternative scenario of short-term multi-stage loading test

Abstract

Glass Fiber Reinforced Polymer pipes (GFRP) are used in a variety of industries such as water, oil and gas, aerospace and chemical industries. In the present paper, the creep response of GFRP pipes undergoing compressive transverse loading is analyzed through experimental observations and numerical modeling. Firstly, the long-term creep response of a GFRP pipe is investigated under single-stage loading till more than 400 days. Then, the creep response of another sample from the same pipe is evaluated under multi-stage loading with four 720-h steps (totally 2880 h). Theoretical modeling is performed using a two-level model based on short-term viscoelastic behavior of resin. A procedure is proposed to replace a long-term creep test under a single stage loading with short-term creep tests with multi-stage loading. The proposed procedure is validated through experimental study. The proposed multi-stage creep test scenario is very valuable to reduce the duration of experimental creep test. Utilizing the proposed method during the design process of a GFRP pipe, the creep response of the pipe can be estimated and its long-term properties can be ensured by performing equivalent short-term tests. The proposed procedure is validated through experimental study.