Young´s modulus measurements in metals using impulse excitation technique

ABSTRACT The impulse excitation, as non-destructive technique, allows to determine the elastic constants of materials by means of measurement of natural frequency of vibration of bars in different modes, excited by an impact in a point. In this work, the Young’s modulus of copper, aluminum and copper-based alloys samples was determined. The measurements were performed using different vibration modes: flexural in supported bars, and longitudinal. As a first step, the Young´s modulus of a sample was determined using different modes, finding consistency in results. On the other hand, the variation of the Young´s modulus was determined as a function of the temperature and microstructural parameters such as grain size. The capabilities and disadvantages of using the impulse excitation technique as a low-cost alternative in the field of research in metals and alloys are analyzed.摘要：脉冲激励法（impulse excitation）作为一种无损检测技术，可通过测量受单点冲击激发的不同振动模式下试样杆的固有振动频率，来确定材料的弹性常数。本研究测定了铜、铝以及铜基合金试样的杨氏模量（Young’s modulus）。本次测试采用了两种不同的振动模式：支承杆弯曲振动模式与纵向振动模式。首先，通过多种振动模式对单一样本的杨氏模量进行测定，结果显示各模式下的测试值具有一致性。此外，本研究还探究了杨氏模量随温度以及晶粒尺寸这类微观组织参数的变化规律。最后，分析了将脉冲激励法作为金属及合金研究领域低成本替代方案的优势与局限性。