高速三维数字图像法测量手机跌落全场应变

为了测量手机跌落时的变形与应变,基于数字图像相关法及双目立体视觉原理,提出一种用于手机跌落试验中变形与应变测量的方法,并研制了相应的高速三维全场应变光学测量系统。针对手机跌落碰撞过程中,角度变化导致散斑匹配失败率高,变形应变场缺损严重的问题,利用高速相机高速采集图像,并改进图像匹配方法,采用顺序逐帧基准匹配,保证了测量精度,提高了应变场完整度。研制了光学测量系统,设计了试验方案,进行了数字图像测量方法与动态应变仪测量结果的对比,对改进的散斑匹配方案进行了验证。试验结果表明,本文的方法使变形应变场的完整度提高了21%,其位移动态测量精度为0.42%,应变测量精度为0.5%。本文的方法和系统可以满足手机跌落碰撞全场变形与应变测量的要求,与传统测量方式相比有明显优势,是研究手机跌落碰撞变形规律的有效途径。

Measurement of full-field strain incell phone dropping test by high-speed 3D digital image correlation method

A three-dimensional deformation method was proposed based on digital image correlation and binocular stereovision to measure the deformation and strain in a cell phone drop test and a 3D full field strain optical measuring system was developed. To solve a problem inherent in the process of collision due to falling in mobile phones, where the change in angle led to a high rate of failure in speckle matching leading to a serious defect in the strain field, high-speed cameras were used for rapid data acquisition of digital images. Furthermore, the speckle matching method was improved using a successive-frame benchmark, and the integrity of the strain field and the measuring accuracy were improved. Subsequently, an optical measurement system was developed and a test scheme was designed. The results measured using the digital image method and the dynamic strain gauge were compared. The improved speckle matching scheme was verified by comparing the data before and after the application of the proposed method. The study proves that this method improved the integrity of the deformation strain field by 21%, the dynamic accuracy of the displacement measurement is 0.42%, and the accuracy of the strain measurement is 0.5%. Compared with traditional measurement methods, this method can measure three-dimensional deformation and strain data of mobile phones more comprehensively and intuitively, and it was an effective way to study the deformation effects in drop tests.