Abstract The present work analyses the reliability of the Brazilian test with loading arcs. A new testing set up has allowed to determine in an effective way the real load of the failure initiation as this moment was not always or correctly detected by the universal testing machine. The instrumentation used is a simple and low-cost method that allows to know the possible pressure distribution in the contact zone as well as the final contact angle. It has been observed that the success of the test depends mainly on the surface finish of the parts involved, their geometric tolerances and the symmetry of the applied load. These boundary conditions have a direct effect in the contact pressure distribution. The possible failure modes observed experimentally have been simulated with the finite element methods. For this, the contact boundary condition has been changed and the possible stress distribution in term of Griffith equivalent stress has been obtained. The numerical analysis allows to study the influence of the initial contact condition on the success of the test and agrees with the experimental results. Furthermore, an uncertainty analysis in the expression of the tensile strength confirms that, when the test is valid, a crack appears suddenly in the central area of the disk, as observed experimentally, so there is no need to determine if the starting point is in the centre. Additionally, it has been observed that the initial crack length depends on the type of pressure distribution in the contact zone. Finally, a series of recommendations are given in order to minimize both the variability of the final contact angle and the risk of premature failure of the Brazilian disk.

中文翻译：

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巴西加载弧试验成功的边界条件实验验证。使用混凝土圆盘的不确定性方法

摘要 目前的工作分析了巴西加载弧试验的可靠性。新的测试装置允许以有效的方式确定故障引发的实际负载，因为万能试验机并不总是或正确地检测到这一时刻。所使用的仪器是一种简单且低成本的方法，可以了解接触区中可能的压力分布以及最终接触角。据观察，测试的成功主要取决于所涉及零件的表面光洁度、它们的几何公差和所施加载荷的对称性。这些边界条件对接触压力分布有直接影响。实验观察到的可能的失效模式已经用有限元方法进行了模拟。为了这，改变了接触边界条件，并获得了可能的 Griffith 等效应力分布。数值分析允许研究初始接触条件对测试成功的影响，并与实验结果一致。此外，拉伸强度表达式的不确定性分析证实，当测试有效时，如实验所观察到的，在圆盘的中心区域突然出现裂纹，因此无需确定起点是否在中心。此外，已经观察到初始裂纹长度取决于接触区压力分布的类型。最后，