This study aims to evaluate the impact of heat treatment on mechanical properties by means of different mechanical measurement methods such as tensile strength and comparison between two results taken by the same test, experimental and 7D image analyses.
In this work, two different types of natural fibers, namely alfa and jute fibers, were used as reinforcing materials for the development of fiber-reinforced hybrid composites. Alfa fiber, due to its availability in the Laghouat region of Algeria, represents a good alternative for the development of an eco-responsible natural reinforcement for plastic composites. In this sub-Saharan region materials are subjected to very high temperatures that can easily reach 50°C and often more. For this reason, the composites of this study made with a weight fraction of 40% of either alfa or jute fibers were subjected to aging in an oven at a temperature of 50°C. A sampling was carried out at regular intervals, i.e. 0, 30 and 60 days.
There is a considerable change between the experimental results and the image analysis software from one element to another, being based on the behavior of each element relative to the other elements of the test piece, which results in a non-homogeneous behavior of the tensile curve.
This initial work highlights the superior potential of polyester composites reinforced with treated esparto fiber, suggests a novel methodology and provides a strong foundation for optimizing and modeling biosourced composite materials intended for thermally sensitive environments. Depending on the type of fiber and the treatment received, thermal aging can either strengthen or weaken specific mechanical directions, according to an analysis of aging-induced anisotropy that clearly shows the differences in the evolution of longitudinal and transverse performances. In order to supplement traditional testing, a sophisticated image analysis technique (7D) was used, which revealed local strain variations of up to ±25% that were not detectable using traditional methods. This demonstrates that in order to investigate composite materials with intricate microstructures, more sensitive measurement instruments are required.
