m cb, (5) where Em∗ is the Young’s modulus of the damaged matrix phase and εcb denotes the mini-composites’ strain at failure, cf. Fig. 3. Presupposing that no fibre-matrix debonding occurs, i.e. εf = εm = εcb, the Young’s modulus Em∗ of the micro-cracked matrix phase follows from the Rule of Mixtures