**Appendix A**

Calculation of scalars *Bi* for calculation of orientation tensor averaged sti ffness tensor from unidirectional sti ffness tensor *Cii* (written in compacted notion) [11]:

$$B\_1 = C\_{11} + C\_{22} - 2C\_{12} - 4C\_{66} \tag{A1}$$

$$B\_2 = \mathbb{C}\_{12} - \mathbb{C}\_{23} \tag{A2}$$

$$B\_3 = \mathcal{C}\_{66} + \frac{1}{2}(\mathcal{C}\_{23} - \mathcal{C}\_{22}) \tag{A3}$$

$$B\_4 = \mathbb{C}\_{23} \tag{A4}$$

$$B\mathfrak{s} = \frac{1}{2}(\mathcal{C}\_{22} - \mathcal{C}\_{23})\tag{A5}$$
