基于应变信号的复合材料层合板低速冲击损伤识别研究

LOW VELOCITY IMPACT DAMAGE IDENTIFICATION OF COMPOSITE LAMINATE USING DYNAMIC STRAIN SIGNALS

为了进行复合材料层合板的冲击损伤识别研究,设计了由小到大的14个等级的冲击能量,对应由小到大的冲击损伤,其中最小能量的冲击没有造成损伤,最大能量的冲击造成穿透复合材料板的损伤。应用冲击过程中测试得到的应变响应进行损伤识别。基于冲击过程中获得的脉冲应变信号,提出了10个新的冲击损伤识别指标:脉冲上升时间、下降时间、总时间、上升时间比下降时间、下降时间比上升时间;脉冲上升面积、下降面积、总面积、上升面积与下降面积之比、下降面积与上升面积之比。将提出的10个新冲击损伤识别指标与冲击能量的关系进行了对比研究。研究表明:脉冲下降时间、脉冲总时间、脉冲下降面积、脉冲总面积与冲击能量之间的关系大体上都是单调的,这4个指标适合0.8J/mm到6.67J/mm的大范围的冲击损伤程度识别,其余6个指标在一定的冲击能量范围内可以识别冲击损伤程度。应用脉冲下降面积、脉冲总面积指标进行了冲击定位识别研究,研究表明,这两个指标也可以识别冲击损伤的位置。

Fourteen levels of impact energy were designed in order to identify the damages of composite laminates. Corresponding to the minimum level of impact energy, composite laminates were intact. Corresponding to the maximum level of impact energy, composite laminates were penetrated through. Strain responses during the impacts were used to detect impulse damages of composite laminate specimens. Based on the collected impulse strain signals under the impacts, the following ten new impact damage indexes are suggested. They are rising shock duration （RSD, the interval from the starting time to peak time of the impact）, descending shock duration （DSD, the interval from the peak time to the end time of the impact）, shock duration （SD, the interval from the starting time to the end time of the impact）, the ratio of the RSD to the DSD, the ratio of the DSD to the RSD, rising area （RA, the integral of the impulse strain response from the starting time to the peak time of the shock）, descending area （DA, the integral of the impulse strain response from the peak time to the end time of the shock）, total area （TA, the integral of the impulse strain response from the starting time to the end time of the shock）, the ratio of the RA to the DA, the ratio of the DA to the RA. The relationship between the ten damage indexes and the impact energies was researched. The results indicate that such indexes as the DSD, the SD, the DA and the TAvary monotonically, depending on the increasing impact energies on the whole. Thusly, the four damage indexes are suitable for identifying the impact energies within the range from 0.8J/mm to 6.67J/mm. The six rest damage indexes can identify impact damage quantification within some shock energy range. The results also show that the DA and TA can also be used to identifv the imnaet locantion.