Damage Evaluation of Two Equatorial Hardwoods under Uniaxial Compression: Case of <i>Entandrophragma cylindricum</i> (Sapelli) and <i>Chlorophora exelcia</i> (Iroko)

Abstract

This work aims at characterizing the evolution of the damage of two tropical hardwoods. Two species from Cameroon, the Entandrophragma Cylindricum and the Chlorora Exelcia were used for the purpose. Repeated compressive loading has been made on specimens strictly selected along with longitudinal and radial directions of each species. Each cycle was made of one phase of monotonic loading and a phase of elastic release. From data obtained, we determined the variation of Young modulus and plastic deformation during each cycle of loading, and we had deduced the damage of the material. Results show that the damage appears only after a certain threshold of the plastic deformation; that damage then grows exponentially to reach a threshold after which the failure of the material occurs. As well, we noticed that the growth of damage is accompanied by the progressive decrease of the Young modulus; this confirms the deteriorating effect of the damage on the mechanical properties. Elsewhere, the damage failure threshold is less than the theoretical value, and differs from one direction to another. Finally, we noticed that the damage failure threshold of sapelli is greater than that of iroko that allows concluding that iroko gets damaged and fails more rapidly than sapelli.

Investigating the Damaging Effects of the Cyclic Discharge in the Uni-Axial Compression of <i>Raphia vinifera</i> L. Arecacea

“…In addition, he observes that the critical threshold of the damage variable is lower than the theoretical value of damage in the 03 directions under loading. This information will be confirmed the same year by the research of Fothe et al [13] during the study of the behavior under cyclic loading of the species Entandrophragma cylindricum (sapelli) and Chlorophora exelcia (iroko).…”

Modeling of the Stress-Strain Relationship of Wood Material Beyond Its Elasticity Limit under Cyclic Compressive Loading: Comparative Study of Two Models

“…The envelope curves of the cyclic compression tests obtained by Fothe et al [29] were plotted and approximated by the models of Mazar-Pijaudiercabot and Fosao-Foudjet. It is observed that both models give a good approximation of the stress-strain curve for stress levels below the yield stress where the material exhibits linear behavior.…”

“…The experimental results used in this study are those obtained by Fothe et al [29] when studying the damage of wood subjected to cyclic compressive loads. Thus, the details of the experimental tests will not be presented in the present work, for more simplicity.…”

“…Thus, the details of the experimental tests will not be presented in the present work, for more simplicity. We invite the reader to refer to [29] for further information. However, we present here some in formations on the experimental device and the Protocol of the tests.…”