Biomechanics and Traditional Use of Raphia matombe Rachis in Northern Angola

The huge rachis of Raphia matombe is intensely used by local people in Northern Angola for the construction of stools, chairs, shelfs, beds, or baskets. This is not only because it is a charming, fast-growing, renewable, and locally abundant material with a high aesthetic value but also due to its extremely light weight structure. Nevertheless, up to now the anatomical and mechanical features of rachises have hardly been studied, although monocotyledonous stem tissues have been the subject of numerous papers. This study presents an analysis of the rachis of Raphia matombe and its material gradients over its whole length and cross-sectional area. The modulus of elasticity increased from the inner towards the outer layers, whereas no clear axial gradient from the base to the apex was found. However, the specific modulus of elasticity increased from the base to the apex in relation to the density, reaching maximum values of 19.0 MPa/kgm-³. Still, the high anatomical and mechanical heterogeneity of the rachis impede quick and easy processing.