Acoustic emission characterization of damage in short hemp‐fiber‐reinforced polypropylene composites

Abstract

This article aims at investigating the effects of hygrothermal aging on the damage mechanisms of short white Hemp Fiber Reinforced Polypropylene (HFRP) composites with various fiber contents (10, 20, 30, and 40 wt%). Injected molded specimens were subjected to hygrothermal aging with a relative humidity of 80% and two temperatures, 25 and 50 C. The water absorption and its effect on tensile properties of HFRP composites were investigated. The Acoustic Emission (AE) technique combined with scanning electron microscopy observations was used to identify microstructural damage events leading to overall failure of the HFRP composites. This identification according to hempfiber content and hygrothermal aging was made with an unsupervised method based on a statistical multivariable analysis (k-means algorithm). The AE results indicate that the quality of fiber-matrix interface plays a major role in the damage process of HFRP composites, shown by the number of AE signals induced by the interface failure and their amplitude ranges.

Effect of alkali treatment on Alfa fibre as reinforcement for polypropylene based eco-composites: Mechanical behaviour and water ageing

“…For the natural fibre reinforced polymer composites, the moisture absorption is strongly related to fibre content because of their hydrophilic nature [25]. Accordingly, we present in Figure 2 the water uptake of untreated and treated AFRP composites according to the water absorption time.…”

“…AE measurements were achieved by using two piezoelectric sensors with a frequency range 100 kHz-1 MHz, coupled on one of the sides of the specimens with silicon grease. More details about adjustment and calibration of the AE system can be found in a previous publication of the authors [25].…”

Evaluation of the damping of hybrid carbon–flax reinforced composites

“…Thus, due to their good specific properties, natural fibres could constitute, in particular applications, an interesting alternative to glass fibres [2,3]. Consequently, various natural fibres reinforced polymer composites were the subject of several studies [4][5][6][7][8][9][10][11][12][13][14]. In particular, the effect of natural fibres treatment on the mechanical properties of these composites, the degradation of their mechanical properties in a hygrothermal environment and their different damage modes during the failure process were studied [4,9,11,14].…”

Failure Assessment and Evaluation of Damage Development and Crack Growth in Polymer Composites Via Localization of Acoustic Emission Events: A Review

“…AE signals may be superimposed, especially in the final stage of the loading; thereby their characteristics can be distorted. Nevertheless, simple burst-type AE parameters may be used well for failure assignment in discontinuous fiber 24,112 and mat-reinforced composites. 33,34,96 However, sophisticated clustering of AE signal characteristics should be used to identify individual damage features 113 and especially to track the failure mode which is associated with a detrimental worsening of performance.…”