A generic approach for analysis of mechanical assembly

• Published in: Precision engineering Vol. 54; pp. 361 - 370
• Main Authors: Liu, Ting, Zhao, Qijian, Cao, Yanlong, Yang, Jiangxin
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.10.2018
• Subjects: Assembly tolerance analysis; Jacobian model; Parallel joints; Serial joints; Skin model shapes; Small displacement torsors; Serial joints; Skin model shapes; Assembly tolerance analysis; Jacobian model; Small displacement torsors; Parallel joints
• ISSN: 0141-6359; 1873-2372
• DOI: 10.1016/j.precisioneng.2018.07.005

Assembly tolerance analysis is increasingly becoming an innovative method for checking whether specified tolerances satisfy assembly functional requirements. Skin model shapes that employ discrete geometry methods can be addressed efficiently when covering geometric tolerances, especially form defects over the product's lifecycle. The point cloud–based discrete geometry uses the actual surfaces to replace the ideal or substitute surfaces in conventional methods, which brings a significant improvement in analysis accuracy and reliability. However, the level of detail and the ordinal simulations restrict their use to simple assemblies. To overcome the issue of the skin model shape in representing deviation propagation, integration of the Jacobian model is proposed; the resulting skin model shapes-Jacobian model combines easy-to-use tolerance propagation and tolerance representation with accuracy guarantees. Besides, Relative positioning method enables calculation of the small displacement torsors for serial or parallel joints, which makes the proposed method a generic approach applicable to both serial and partial parallel kinematic chains. The obtained torsors in the Jacobian model are then used to calculate the final deviations of the functional requirement. The approach is finally illustrated by a practical example. •Application of skin model shapes represents the real surface for each toleranced feature in mechanical assembly.•Integration of Jacobian model overcome the issue of skin model shape in representing deviation propagation.•The integrated model is a generic approach applicable to both serial and partial parallel kinematic chain.