TY - JOUR
T1 - Forming characteristics of Al-alloy large-diameter thin-walled tubes in NC-bending under axial compressive loads
AU - Jing, Yan
AU - He, Yang
AU - Mei, Zhan
AU - Heng, Li
PY - 2010/8
Y1 - 2010/8
N2 - Tube thinning control without wrinkling occurring is a key problem urgently to be solved for improving the forming qualities in numerical control (NC) bending processes of large-diameter Al-alloy thin-walled tubes (AATTs). It may be a way solving this problem to exert axial compression loads (ACL) on the tube end in the bending. Thus, this article establishes a three-dimensional (3D) elastic-plastic explicit finite element (FE) model for the bending under ACL and has its reliability verified. Through a multi-index orthogonal experiment design, a combination of process parameters, each expressed by a proper range, for this FE model is derived to overcome the compression instability on tube ends. By combining the FE model with a wrinkling energy prediction model, an in-depth study is conducted on the forming characteristics of large-diameter AATTs with small bending radii and it can be concluded that (1) The larger the tube diameters and the smaller the bending radii, the larger the induced tangent tension stress zones on tube intrados, by which the tube maximum tangent compression stress zones will be partitioned in the bending processes; thus, the smaller the ACL roles in decreasing thinning degrees and the larger the compression instability possibilities on tube ends. (2) The tube wrinkling possibilities under ACL are larger than without ACL acting in the earlier forming periods, and smaller in the later ones. (3) For the tubes with a size factor less than 80, the ACL roles in decreasing thinning degrees are stronger than in increasing wrinkling possibilities.
AB - Tube thinning control without wrinkling occurring is a key problem urgently to be solved for improving the forming qualities in numerical control (NC) bending processes of large-diameter Al-alloy thin-walled tubes (AATTs). It may be a way solving this problem to exert axial compression loads (ACL) on the tube end in the bending. Thus, this article establishes a three-dimensional (3D) elastic-plastic explicit finite element (FE) model for the bending under ACL and has its reliability verified. Through a multi-index orthogonal experiment design, a combination of process parameters, each expressed by a proper range, for this FE model is derived to overcome the compression instability on tube ends. By combining the FE model with a wrinkling energy prediction model, an in-depth study is conducted on the forming characteristics of large-diameter AATTs with small bending radii and it can be concluded that (1) The larger the tube diameters and the smaller the bending radii, the larger the induced tangent tension stress zones on tube intrados, by which the tube maximum tangent compression stress zones will be partitioned in the bending processes; thus, the smaller the ACL roles in decreasing thinning degrees and the larger the compression instability possibilities on tube ends. (2) The tube wrinkling possibilities under ACL are larger than without ACL acting in the earlier forming periods, and smaller in the later ones. (3) For the tubes with a size factor less than 80, the ACL roles in decreasing thinning degrees are stronger than in increasing wrinkling possibilities.
KW - axial compression
KW - bending
KW - finite element modeling
KW - forming
KW - large-diameter Al-alloy thin-walled tubes
KW - numerical control systems
UR - http://www.scopus.com/inward/record.url?scp=77955862439&partnerID=8YFLogxK
U2 - 10.1016/S1000-9361(09)60242-9
DO - 10.1016/S1000-9361(09)60242-9
M3 - 文章
AN - SCOPUS:77955862439
SN - 1000-9361
VL - 23
SP - 461
EP - 469
JO - Chinese Journal of Aeronautics
JF - Chinese Journal of Aeronautics
IS - 4
ER -