Peng Da-shu

Analysis of clad sheet bonding by cold rolling

Abstract In this paper, clad sheet bonding by cold rolling has been analyzed in depth using the stream function method and the upper bound theorem. Not only have the curvature, the thickness ratio of the rolled product and rolling force, but also the locations of the neutral points and the bond point have been obtained. It is found that at low total thickness reduction, the neutral point on the upper roll contacting the harder sheet usually more closely approaches the entrance of the roll-gap than does neutral point on the lower roll. As the thickness reduction increases, the difference gradually diminishes and even reverses. It is also found that the location of the bond point at the interface is to some extent related to the initial clad ratio. A smaller the clad ratio before rolling may bring the bond point closer to the entrance of the roll-gap, which means a longer bonded length at the interface. Based on this analysis, some means of contributing to the promotion of bond strength are proposed.

Establishment of constitutive relationship model for 2519 aluminum alloy based on BP artificial neural network

An isothermal compressive experiment using Gleeble 1500 thermal simulator was studied to acquire flow stress at different deformation temperatures, strains and strain rates. The artificial neural networks with the error back propagation(BP) algorithm was used to establish constitutive model of 2519 aluminum alloy based on the experiment data. The model results show that the systematical error is small(δ=3.3%) when the value of objective function is 0.2, the number of nodes in the hidden layer is 5 and the learning rate is 0.1. Flow stresses of the material under various thermodynamic conditions are predicted by the neural network model, and the predicted results correspond with the experimental results. A knowledge-based constitutive relation model is developed.

Numerical modelling of gold-roll bonding of clad metal sheets

An analytical model based on the rigid-plastic finite-element formulation for slightly compressible materials is newly proposed to examine the bonding behavior at the roll gap during clad metal sheets rolling. The interfacial elements inserted between the two metals, which are characteristic of the shear-susceptible deformation with the help of the shear factor in the expression of effective strain rate, are used to model the relative slidding at the interface. It is found that the proposed method is applicable to the simulation of clad metal sheets rolling.

Pressure distribution on the grip zones in the CONFORM process

The pressure distribution on the grip zones in the CONFORM process has been analysed by means of the slab method, and from the above results the forces applied to the shoe were derived. It is shown that the pressure along the segment increases powerfully withϑ increasing in the primary grip, and increases linearly withϑ increasing in the extrusion grip. Thus, it can offer mechanics parameters for the operating techniques and CONFORM machine design.