基于数字图像相关的近熔池应变场原位测量

焊接时进行原位应变测量可以直接观测焊接过程中的力学现象,同时也可以用于验证焊接过程计算机模型。目前常见应变测量方法主要采用应变片,无法得到全场应变。使用数字图像相关(DIC)技术,测量了在不锈钢厚板表面进行激光堆焊时熔池周围的应变场分布,直接观测由于焊接过程中的非均匀热膨胀造成的焊接热影响区及其周围材料的变形。结果表明,在熔池侧面存在一定的负应变。在熔池后,随着材料逐步冷却,最终形成了正应变。

In-situ Strain Measurement near Weld Pool Using Digital Image Correlation

In-situ measurement of strain is important to understand mechanics during welding. It is also a useful method to validate computational model of weld process. This work utilized 3D digital image correlation (DIC) techniques to measure the strain field near weld pool on a 304L stainless steel plate during laser welding. The deformation in heat affected zone caused by non-uniform thermal expansion was studied. The results show that during welding, there was a negative strain zone immediately adjacent to the weld pool. However, as the plate was cooled down to room temperature, the transverse strain became less negative and finally the positive residual strain was retained in heat affected zone.