A methodology for describing creep‐fatigue interactions in thermoplastic components

Abstract

In service, some plastics components are subjected to intimate mixtures of creep and fatigue loading, such that both have the potential to cause component failure. This paper examines, for the case of a single design of an injection molded fitting that comprised part of a polyethylene pipeline system, the response of that fitting to fatigue loading patterns that included significant elements of creep loading. The performance of the fitting was monitored and the data interpreted in terms of the concepts of fractional fatigue and fractional creep damage. The approach helps in identifying the design criteria to be used for components that are to be subjected to complex fatigue loadings. For the cases where significant creep‐fatigue interactions occur, such that the additive damage was nonlinear, the method can identify critical frequencies at which maximum damage occurs. This style of analysis will be most useful for plastics components that are used in critical applications where failure has to be avoided.

Creep–Fatigue Relationship in Polymer: Molecular Dynamics Simulations Approach

“…This confirms previous experimental work [13,15] that indicated the same processes are happening in both conditions. If fatigue and creep are based on chains sliding against each other as indicated by the MD simulations, it can be speculated that blocking the possibility to slide would increase fatigue and creep performance.…”

Tensile, creep and fatigue behaviours of short fibre reinforced polymer composites at elevated temperatures: a literature survey

“…Bowman and Barker examined effect of creep–fatigue loading condition on a polyethylene pipeline component experimentally. The stress‐controlled tests were done on an injection moulded 90° Tee type pipeline component by applying cyclic waveforms with different hold‐times.…”

“…Cross plot of fractional stress rupture damage against fractional fatigue damage for polyethylene pipeline component …”

“…28 Cross plot of fractional stress rupture damage against fractional fatigue damage for polyethylene pipeline component. 76 TMF and creep-fatigue interaction of SFRPCs, although complex topics, are of highly practical nature because of the operating environment of many components and structures made of these materials. Experimental and analytical studies on this topic are currently scarce.…”

Cyclic creep and creep-fatigue interaction in sandwich beams

“…In order for meaningful results to be gained from the creepfatigue interaction damage from equation (12), it is important to obtain suitable creep stress rupture times, T CR , and pure fatigue lifetime data for determination of N 0 f . Because the author's experimental programme did not include extensive creep testing displaying stress ruptures and also pure fatigue cycling, it was found in some cases necessary to use other published shear test data with the same 'Airex' R63.80 core material.…”