Electromagnetic Gage Techniques for Dynamic Tensile Fracture

硬岩的开挖受动态拉伸断裂控制，这是一个鲜为人知的过程。关于岩石和陶瓷等脆性材料的动态抗拉强度的现有数据非常有限，而且现有数据存在问题，因为这些数据是通过表面测量获得的，而表面流动可能会对断裂特性产生影响。这个研究项目涉及到动态抗拉强度的测量，在测试试样的内部放置一个嵌入的量规。具体地说，该研究计划需要开发一种小尺寸的电磁计，它可以检测与施加的动态应力有关的粒子速度。在标本中放置测量仪器的技术将是该项目的重要组成部分。这些数据将被数字化记录并自动处理，以在动态破裂过程中给出速度、位移和应力作为时间的函数。将演示该方法，并确定几种脆性岩石、塑料、复合材料和陶瓷的动态拉伸强度和/或韧性。Sunburst Recovery是一家小公司，有一个很好的实验室来进行这个实验项目。首席研究员具有良好的岩石力学背景，并证明了使用电磁换能器测量地质材料性质的可行性。建议颁发奖项。

YOUNG Excavation of hard rock is controlled by dynamic tensile fracture which is a process that is poorly understood. Available data on the dynamic tensile strength of brittle materials such as rocks and ceramics is extremely limited, and the data available is open to question because it is obtained by surface measurements where surface flws may have an influence on the fracture properties. This research program involves the measurement of dynamic tensile strength with an embedded gage placed in the interior of the test specimen. Specifically, the research program entails the development of an electromagnetic gage of small dimension which will sense particle velocities which can be related to the imposed dynamic stresses. Gage placment techniques in the specimen will be an important part of the project. The data will be recorded digitally and processed automaticallly to give velocity, displacement and stress as a function of time during the dynamic fracture process. The method will be demonstrated and dynamic tensile strength and/or toughness will be determined for several brittle rocks, plastics, composites and ceramics. Sunburst Recovery is a small company with an excellent laboratory for conducting this experimental program. The principal investigator has an excellent background in rock mechanics and has shown the feasibility of using electromagnetic transducers in measuring properties of geo- materials. An award is recommended.