This work uses the M-theta method on a new proposed specimen called "I-specimen" for the numerical modeling of cracks on some tropical hardwoods in general and in particular on some Cameroonian woods. The finite element analysis of fracture in an orthotropic medium is developed. The fracture algorithm is introduced in a finite element software Cast3M and, with an incremental orthotropic formulation, the simulation of crack growth is computed. Using this method, stress intensity factors and energy release rate are calculated for Mode I and II failures. The energy release rate and stress intensity factors are numerically deduced using “I-specimen” to characterize three Cameroonian hardwoods under mode I and II loading for different crack growths. The specimen used has better characteristics than other samples generally used in the literature and its geometry is very simple to define. The proposal of a new geometry that can guarantee the reproduction of the different failure modes while exhibiting some stability of the crack parameters G and K during propagation was evaluated and compared to other specimens given by the fracture mechanics literature. For each fracture mode, the influence of the orthotropy rate parameters on the energy release rate was investigated.

这项工作在一个名为“I-specimen”的新提议样本上使用 M-theta 方法，用于对一些热带硬木（特别是一些喀麦隆木材）的裂缝进行数值模拟。开发了正交各向异性介质中断裂的有限元分析。在有限元软件 Cast3M 中引入断裂算法，并使用增量正交各向异性公式计算裂纹扩展的模拟。使用该方法，可以计算 I 型和 II 型故障的应力强度因子和能量释放率。使用“I-样本”对三种喀麦隆硬木在不同裂纹扩展的模式 I 和 II 加载下的特征进行了数值推导，得出了能量释放率和应力强度因子。所使用的样本比文献中通常使用的其他样本具有更好的特性，并且其几何形状非常容易定义。评估了新几何形状的提议，该几何形状可以保证不同失效模式的再现，同时在扩展过程中表现出裂纹参数 G 和 K 的一定稳定性，并与断裂力学文献给出的其他样本进行了比较。对于每种断裂模式，研究了正交各向异性率参数对能量释放率的影响。