Analysis of stamping residual stress of the crossm

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Analysis of stamping residual stress of car crossbeam

Abstract: the car rear axle crossbeam is formed by stamping with steel plates, and notches are punched at both ends. For car rear axle beam at 0 According to the cracking condition after the reliability strengthening test of 0 million km, the residual stress in two kinds of beams punched with pits of different depths was tested by blind hole method, and the distribution and change of residual stress were analyzed and compared. The results show that stamping will produce large residual stress in the beam, and the stamping process of the beam with deep pits is better than that of the beam with shallow pits

key words: car beam; Stamping residual stress analysis; Blind hole method

the rear axle of modern cars usually adopts the welded structure of composite rear suspension. The cross section of the crossbeam in the rear suspension is V-shaped, which is stamped by 6mm5 steel plate with the output result of the film tensile testing machine. There are stamping pits at the bottom of the V-shaped, as shown in Figure 1 0 The reliability enhancement test of 0 million km shows that the rear axle will produce cracks perpendicular to the axis of the beam near the pit of the beam after being used for a period of time. Among the many factors that cause cracks, residual stress will reduce the fatigue strength, stress embrittlement and stress corrosion resistance of materials, so it is one of the factors worthy of attention. Studying the influence of the stamping process of the beam on the residual stress is of great significance to reasonably design the stamping process of the beam, improve the manufacturing quality and prolong its service life. In this paper, the punching residual stress in the beam formed by two different punching processes (one is deep, called beam 1; the other is shallow, called beam 2) is tested, compared and analyzed by using the blind hole method

, where a and B are release coefficients, which are determined by experiments. σ 1 and σ 2 is the residual principal stress at point O before drilling, θ Is residual principal stress σ The included angle between 1 and the sensitive grid 1 of the residual stress-strain flower (counterclockwise rotation is positive), as shown in Figure 2

according to formula (1), for the residual stress and strain flowers shown in Figure 2, the release strains measured by the sensitive grid 1, 2 and 3 are respectively

2. The test results of the stamping residual stress of the beam

2.1 determination of the release coefficient

the plate used for the beam is processed into a dumbbell shaped test piece, and five residual stress and strain flowers are pasted on the test piece (the sensitive grid 1 is along the axis of the test piece), of which three are pasted on the axis of the test piece to determine the release coefficient, The other two are symmetrically pasted on both sides of the specimen to monitor the loading and make the specimen produce unidirectional tension. Install the test pieces on the universal testing machine before and after drilling, and repeat the loading σ

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