scholarly journals Effects of Residual Stress and Equivalent Bending Stiffness on the Dimensional Stability of the Thin-Walled Parts

2021 ◽  
Author(s):  
Hanjun Gao ◽  
Xin Li ◽  
Qiong Wu ◽  
Minghui Lin ◽  
Yidu Zhang
Keyword(s):  
Residual Stress ◽  
Dimensional Stability ◽  
Removal Rate ◽  
Optimization Technique ◽  
Bending Stiffness ◽  
Topological Optimization ◽  
Machining Deformation ◽  
Equivalent Bending Stiffness ◽  
Measuring Machine ◽  
Thin Walled

Abstract The monolithic thin-walled parts are widely used in the aeronautic and astronautic field because of its excellent mechanical performance and light weight, but the thin-walled parts are vulnerable to the machining deformation due to its low stiffness and high material removal rate. According to the relative basic theory, the stiffness and internal residual stress of the part are the critical factors affecting the dimensional stability. In this work, the influences of equivalent bending stiffness and residual stress on the dimensional stability of thin-walled parts are studied. Nine typical thin-walled parts in three groups with two materials (7075 aluminum alloy for A1~A3 and B1~B3, and Ti6Al4V titanium alloy for B4~B6) are machined and treated with different processes. Topology optimization technique is used to optimize the structure of parts to enhance the bending stiffness. Corresponding finite element method (FEM) simulations are carried out to further investigate the generation mechanism. The deformations in 312 hours after machining are measured using coordinate measuring machine, and the deformation changes of the parts are obtained and analyzed. Finally, based on topological optimization and stress relief technology, a machining deformation control method for the monolithic thin-walled parts is proposed. Results show that the maximum and average deformations of thin-walled are evidently decreased using the proposed method.

scholarly journals Effects of TVSR process on the dimensional stability and residual stress of 7075 aluminum alloy parts

2021 ◽  
Vol 60 (1) ◽  
pp. 631-642
Author(s):  
Yan Xu ◽  
Zhongjun Shi ◽  
Bianhong Li ◽  
Zhang Zhang
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Dimensional Stability ◽  
Stress Relief ◽  
Bending Stiffness ◽  
Machining Process ◽  
7075 Aluminum Alloy ◽  
Maximum Deformation ◽  
Equivalent Bending Stiffness ◽  
Thin Walled

Abstract Residual stress generated during the blank forming and machining process significantly influences the dimensional stability of the mechanical parts. The equivalent bending stiffness and thermal vibration stress relief (TVSR) are two factors that affect the deformation of thin-walled workpiece. To increase the machining accuracy, on the one hand, increase the equivalent bending stiffness in manufacturing, and on the other hand, usually conduct the stress relief process to reduce the residual stress in manufacturing. In the present study, morphology optimization and TVSR process are conducted on a thin-walled part Specimen B of 7075 aluminum alloy to control the residual stress and machining deformation before finish machining. As a contrast, Specimen A is machined in one step. The deformations vary with time of Specimen A and B are measured. The corresponding finite element model is built to further study the stress and distortion during the machining process. Results showed that (1) deformation decreased with the increase of equivalent bending stiffness, compared with Specimen A, the maximum deformation of Specimen B decreased by 58.28%. (2) The final maximum deformation of Specimen B can be reduced by 38.33% by topology reinforcement to improve the equivalent stiffness and TVSR to reduce the residual stress.

scholarly journals Improving accuracy of bulk residual stress characterization in ribbed geometries through equivalent bending stiffness

Procedia CIRP ◽  
2021 ◽  
Vol 102 ◽  
pp. 325-330
Author(s):  
Maria Aurrekoetxea ◽  
Iñigo Llanos ◽  
Oier Zelaieta ◽  
Luis Norberto Lopez de Lacalle
Keyword(s):  
Residual Stress ◽  
Bending Stiffness ◽  
Equivalent Bending Stiffness ◽  
Improving Accuracy

Deformation Control and Chatter Suppression in 5-Axis Milling of Thin-Walled Blade

2011 ◽  
Vol 188 ◽  
pp. 314-318
Author(s):  
Bao Hai Wu ◽  
Ming Luo ◽  
Ding Hua Zhang ◽  
X. Zhou
Keyword(s):  
Residual Stress ◽  
Deformation Control ◽  
Tool Paths ◽  
Machining Quality ◽  
Chatter Suppression ◽  
Machining Deformation ◽  
Thin Walled

This paper deals with deformation control and chatter suppression in the milling of thin-walled blade. The purpose is to generate tool paths that can control machining deformation and suppress chatter during milling. To achieve this object, symmetrical spiral milling approach is proposed to release residual stress on both sides of the blade in the same machining circle to control machining deformation. Besides, in order to suppress chatter during milling of thin-walled blade, nonuniform-allowance is left on both sides of the blade during machining, this can effectively increase the rigidity, thereby chatter cannot easily occur during machining. Machining experiments showed that the proposed approaches can dramatically improve the machining quality, decrease deformation and suppress chatter in the milling of thin-walled blade.

Numerical Simulation Investigation on Machining Deformation of Aviation Thin-Walled Parts Caused by Residual Stress

2021 ◽  
Vol 1032 ◽  
pp. 186-191
Author(s):  
Jie Deng ◽  
Shi Jie Zhou ◽  
Han Jun Gao ◽  
Ming Hui Lin ◽  
Xin Li
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Residual Stresses ◽  
Simulation Models ◽  
Cutting Parameters ◽  
Stress Distributions ◽  
Machining Deformation ◽  
Proposed Model ◽  
Thin Walled ◽  
Structural Parts

Holistic thin-walled parts are common structural parts of modern aircraft to reduce the weight and increase the stiffness. Over 90% of the materials are removed from the blank, as a result, large machining deformations occur to the parts, which causes the manufacturing discrepancies and even the scrap parts. In this paper, numerical simulation models are established to predict the machining deformation of two typical aviation thin-walled parts. The blank initial and machining induced residual stresses, as well as the cutting parameters, are considered in the model. The deformations and stresses after machining are calculated using the proposed model, and the deformation and stress distributions are analyzed.

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