Evaluate the Fatigue Life of CFRC Subjected to Coupled Thermo–Mechanical Loading

Abstract

Mechanical properties of composites manufactured by high-temperature polymer polyether ether ketone (PEEK) with continuous reinforced fibers are closely dependent on ambient temperature variations. In order to effectively study fatigue failure behaviors of composites under the coupled thermo–mechanical loading, a well-established microscopic model based on a representative volume element (RVE) is proposed in this paper. Stiffness degradation behaviors of the composite laminates at room and elevated temperatures are firstly investigated, and their failure strengths are compared with experimental data. To describe the fatigue behaviors of composites with respect to complex external loading and ambient temperature variations, a new fatigue equation is proposed. A good consistency between theoretical results and experimental data was found in the cases. On this basis, the temperature cycling effects on the service life of composites are also discussed. Microscopic stress distributions of the RVE are also discussed to reveal their fatigue failure mechanisms.

The Shape Memory Properties and Actuation Performances of 4D Printing Poly (Ether-Ether-Ketone)

“…Moreover, the unique high-temperature resistance and radiation-resistant properties [18,19] endow PEEK with a more extensive prospect than other SMPs as an aerospace material. Existing research for PEEK mainly aims at enhancing its mechanical properties [20][21][22][23], such as chemical modification [24] and fiber-reinforced integration [25,26]. Though the shape memory effect of PEEK was characterized in a previous study under small strain with tensile mode [27], bending rather than tension is the main actuation method in the applications of SMPs [28][29][30].…”

New jig adapted for compression fatigue tests on composite materials

“…Particularly, the carbon fiber reinforced polymer (CFRP) composite fatigue life limit reaches about 60 to 80% of their static stress limit value, while in metals this limit is around 30%. [4][5][6] Besides, under inevitable fatigue loads, different damage profiles in composites can arise during service. In general, these damages, regardless of if the load is applied by tensile, shear or compression, can be divided in three main phases as following: matrix cracks, delamination of the fiber/matrix interface and fiber breaks.…”

“…In general, these damages, regardless of if the load is applied by tensile, shear or compression, can be divided in three main phases as following: matrix cracks, delamination of the fiber/matrix interface and fiber breaks. [6][7][8][9] In aircraft structures these events can occur simultaneously. Delamination refers to the separation between adjacent layers due to the failure of the interply resin interface.…”