Round-robin programme for longitudinal tensile testing of unidirectional composites: results, conclusions, and recommendations

作者：Babak Fazlali, Christian Breite, Gergely Czél, Bodo Fiedler, Dennis Gibhardt, Masaki Hojo, H. Koerber, Rajnish Kumar, M.L. Velasco, Ian McEnteggart, Lars Pilgaard Mikkelsen, F. Parı́s, Ichiro Taketa, Michael R. Wisnom, Yentl Swolfs · 发表于：Polymer Testing · 年份：2025 · DOI：10.1016/j.polymertesting.2025.108974 · 被引用次数：4 · 研究领域：Mechanical Behavior of Composites、Structural Behavior of Reinforced Concrete、Structural Load-Bearing Analysis

The longitudinal tensile behaviour is one of the most important and basic characteristics of a unidirectional composite, yet its experimental characterisation is not straightforward. Therefore, we conducted a round-robin programme with seven test labs and six coupon designs where the panels were manufactured and cut by the same lab. Our results indicate that careful manufacturing and cutting enable consistent and reliable results for the different labs and coupon designs. High-speed videos confirmed that many coupons failed away from the grips, which is the targeted failure location. In addition to the modulus, failure strain and strength results, we present results and novel recommendations related to the coupon preparation and testing methodology. We recommend using a non-contact strain measurement method and discarding tests with significant stress drops before final failure. • An extensive round-robin programme with seven labs and six coupon designs is presented. • Rigorous test plate and coupon preparation resulted in particularly low variation. • Most of the novel coupon geometries matched or exceeded the results of standard ones. • Non-contact strain measurement methods performed better for failure strain determination. • Coupons that experienced more than 3 % load drop before failure should be disregarded.