Stability analysis of free-form workpieces in fixtures

The stability analysis of workpiece in fixtures is considered as one of the stages of the fixture verification system. The stability of free-form workpieces in fixtures is affected by different agents including weight, locators, clamps and machining wrenches. In this study, a mathematical model has been presented for part stability analysis based on the minimum norm principle that led to a non-linear quadratic optimization problem. The solution to this problem is the reaction forces at the contact points between workpiece and locators. The study includes the workpiece stability analysis at the loading stages, determination of stability span for workpiece and the investigating the effect of the base locators distances on the workpiece stability through examples. A turbine blade model was incorporated as the case study to evaluate the suggested model capabilities in stability analysis. The loading procedure of this part into the fixture was categorized into sequential stages and its stability was investigated in contact with the locators. The results included the stability span of [15°-58°] for the workpiece on base locators, increased stability by the distanced base locators and the confirmation of the main locating plan through the stability verification at the loading stages. The results showed the model efficiency and accuracy in analyzing the free-form part stability in contact with the fixture elements. The proposed dexterous model can be integrated into the CAFD platform to be used at the early stages of locating and clamping system design applications.