The equivalent laminate assumption is a commonly-used method to model the random architecture of discontinuous composites, but which has never been validated experimentally. This study aims to verify the equivalent laminate assumption, focusing on tow-based discontinuous composites (TBDCs), which have higher fibre-content and thus improved modulus and strength, compared to conventional discontinuous-fibre composites. This verification was achieved by manufacturing and testing (i) actual TBDCs with randomly oriented tows and (ii) their equivalent laminates (ELs), at two different tow thicknesses. The results show that ELs exhibit the same failure mechanisms as TBDCs, and are similarly weakened by an increase in tow thickness. However, ELs lack the spatial variability in local fibre-content and local tow orientations, which makes ELs stronger than TBDCs. Therefore, the equivalent laminate assumption is suitable for predicting the modulus of discontinuous composites, but cannot predict their strength without considering the local variability in their microstructure.

等效叠层假设是对不连续复合材料的随机结构进行建模的常用方法，但尚未经过实验验证。这项研究旨在验证等效叠层假设，重点放在基于丝束的不连续复合材料（TBDC）上，与传统的不连续纤维复合材料相比，它们具有更高的纤维含量，从而改善了模量和强度。通过生产和测试（i）具有随机取向的丝束的实际TBDC和（ii）两种不同丝束厚度的等效层压板（EL）来进行此验证。结果表明，ELs具有与TBDCs相同的失效机理，并且由于丝束厚度的增加而被削弱。但是，ELs在局部纤维含量和局部丝束取向方面缺乏空间可变性，这使得EL的性能比TBDC强。因此，等效的叠层假设适合于预测不连续复合材料的模量，但如果不考虑其微观结构的局部变化性就无法预测其强度。