Development of similarity-based scaling criteria for creep age forming of large/extra-large panels

Abstract

A scaling method is developed for the creep age forming (CAF) process to downscale manufacturing of large/extra-large panels to lab-scale experimental trials for industrial application. Similarity theory is applied to identify both the geometrical and physical (non-geometrical) similarities between large-size prototypes and scaled-down models in all process stages of CAF, including loading, stress-relaxation and unloading (springback). A constitutive model is incorporated into the theory in order to identify the similarity in the highly non-linear stress-relaxation behaviour for aluminium alloy plates during CAF, and to obtain the effective scaling criteria for the CAFed plates after springback. The method was demonstrated by scaling down CAF manufacturing of both singly curved and doubly curved large plates under both proportional and non-proportional geometrical scaling conditions. The analytical results of the scaling method and numerical results obtained by CAF FE modelling were found to be in good agreement. Scaling diagrams linking the key deformation (springback) and structural (flexural rigidity) variables to scaling ratios under both proportional and non-proportional conditions were generated, and the developed scaling diagrams have been validated by corresponding CAF experiments. The scaling method developed in this study provides guidance on the design of scaled-down CAF experimental trials and will be used in the practical CAF process of large/extra-large panels.

Evaluation of drawing force by a new dimensionless method in deep drawing process

“…1–6 Also, it should be noted that even though the scale changing for generalization of experimental results is not a new challenge and has been extensively used in fluid and dynamic applications, so far no attention has been paid to use it in metal forming. 7–9…”

“…[1][2][3][4][5][6] Also, it should be noted that even though the scale changing for generalization of experimental results is not a new challenge and has been extensively used in fluid and dynamic applications, so far no attention has been paid to use it in metal forming. [7][8][9] Dimensional analysis plays an important role in evaluating the process on different scales. Although this method depends on the complexity of the problem, its simplicity, where there is no need for understanding of the fundamental process model, general dimensionless process model diagnosis and process trend prediction in different scales are the most important advantages of this method.…”