Fatigue crack propagation in polypropylene reinforced with short glass fibres

Fatigue Fracture of Neat and Short Glass Fiber Reinforced Polypropylene: Effect of Frequency and Material Orientation

“…In the first stage of the fatigue test the FCP rate decreases as already observed in previous works [2,5,10] for both neat and short glass fiber reinforced …”

“…In particular, the fatigue properties are of paramount importance for many intended applications where components are subjected to load and environmental histories which vary in time over the period of service [2][3][4][5][6][7][8][9][10]. Fatigue damage is associated with the initiation and propagation of cracks in the matrix and/or the destruction of the bonding at the fiber/matrix interface.…”

“…Fatigue damage is associated with the initiation and propagation of cracks in the matrix and/or the destruction of the bonding at the fiber/matrix interface. Final failure of PP and its short-fiber reinforced (SFR) composites under alternating loadings, mainly occurs by fatigue crack propagation (FCP) [2,5,6,10] characterized by a stable crack acceleration range which can be reasonably well described by the Paris-Erdogan relationship [11]: (1) where da/dN is the crack growth per each cycle, A and n are constants and ∆K is the stress intensity amplitude at the crack tip under mode I (opening mode). In general, the most important testing variables affecting the FCP rate are frequency and wave form of the alternating load, temperature, environment, stress ratio and mean load [5].…”

Effect of Thickness on Fatigue Crack Propagation in Injection Molded Short Carbon Fiber Reinforced Plastics

“…The fiber orientation produced by injection molding has a big influence on the propagation rate and path of fatigue cracks [1][2][3][4][5][6][7][8]. Because the crack propagation rate perpendicular to aligned fibers is much slower than that parallel to fibers, the crack propagation rate is different between in the shell layer and in the core layer.…”

Evaluation of Structural Degradation of Polymeric Composites Subjected to Self-Heating by the Thermal Diffusivity Analysis

“…This is because a major amount of dissipated mechanical energy transforms into heat; however, a small amount of this energy dissipates toward development of plastic mechanisms [2] and microcracking [3]. The degradation process of a composite structure under conditions of fatigue loading accompanied with the self-heating effect can be featured with a characteristic three-stage degradation model, which is observable both in decrease in mechanical properties [4,5] as well as in evolution of the self-heating temperature [1,6,7]. The selfheating effect, due to the character of its development, can be classified into two types: In the first case, when stationary self-heating occurs, the self-heating temperature grows until reaching a certain temperature value and stabilizes at this value due to reaching a thermal equilibrium between the generated and convected thermal energy, while in the second case, the self-heating temperature growth has nonstationary character, which leads to significant influence and domination on the fatigue process.…”