Investigation of the Influence of Viscoelastic Behaviour on the Lifetime of Short Fibre Reinforced Polymers

Abstract

Short fibre reinforced polymers are getting more important for structural applications. Becasue of lightweight actions, components are designed for a specific application and lifetime. The bearable numbers of cycles can be estimated using material data and models for the consideration of influence factors. Further static loadings affect material behaviour, which influences the component lifetime. Commonly used models are not able to capture these effects. Therefore, material tests, with different load sequences, on 40% short glass fibre reinforced polypropylene have been performed. These sequences are combinations of cyclic and static loads at different, defined levels. Our research shows a lifetime elongation or reduction of a polymer, depending on the amount of static load time and quantity. For a certain stress level, the time to failure can be elongated or shortened more than a decade by another stress level, as compared to pure cyclic load. Additionally, the stiffness development of the composite is investigated in order to capture the damage course. Accordingly, these effects needed to be considered in lifetime prediction.

Effect of the Glass Fiber Content of a Polybutylene Terephthalate Reinforced Composite Structure on Physical and Mechanical Characteristics

“…After increasing the GF rate in the structure, same behavior as PBT/GF composite was noted for PA66, polyester and rubber-toughened nylon 6, where there was an increase in fragility expressed by the increase in the tensile strength and Young modulus versus a decrease in the elongation at break [ 2 , 5 , 8 , 9 ]. The same trend of ameliorating the mechanical properties and especially increasing tensile strength when increasing the percentage of GF reinforcement was found in the literature [ 6 , 7 , 9 , 23 , 24 ]. PLA (Poly(Lactic)Acid) reinforced by different GF rates showed a linear decrease in elongation at break and a linear increase in Young’s modulus and tensile strength [ 7 ].…”

Accounting for viscoelastic effects in a multiscale fatigue model for the degradation of the dynamic stiffness of short-fiber reinforced thermoplastics

“…Abdo et al [13] studied frequency-dependent loss and storage moduli of fiber reinforced PBT. Stadler et al [14] investigated the life time of short fiber reinforced polymers under combined cyclic and creep load.…”

Investigation of the geometric parameters on the performance of glass fiber reinforced polymer laminated mechanical joints under fatigue loading

“…In certain applications, components experience repeated loads over time, which gradually lead to damage and reduced material strength. 8,9 Ferdous et al 10 explored vinyl ester GFRP composite laminate behavior across stress levels (25%-80% of ultimate tensile strength (UTS)) and loading frequencies in tension fatigue tests. Findings indicate pure tension failure at high stress, with stress concentration dominating at low stress.…”