Existing methods cannot satisfy the reliability allocation demands of the early design phase for the modern complex system of NC turrets. Motivated by the need of practical application, this paper proposes a new and practical reliability allocation method in the early design stage for NC turrets considering failure mode and system complexity, information inaccessibility, and expert knowledge limitation. First, the fault tree of a NC turret is quickly built to clear the relationship between the system’s compositions and failure modes up. Second, the happening probability of each failure event in the fault tree is firstly calculated by fuzzy expert evaluation to provide the reliability allocation with complete information. Third, by discussing the practical meaning of every layer in the fault tree, the proposed allocation strategy is within the experts’ knowledge scope for evaluating accurately. Eventually, the application result of the AK36100 A turret is presented and compared with some existing allocation methods, illustrating the rationality of the proposed allocation method.

The theory of generating-line method has been discussed in this study. It is a new theory of manufacturing spiral bevel gears of which tooth surfaces are formed by exact spherical involutes. The tooth surface of spiral bevel gears is obtained by the pure-rolling motion between the base cone and the great circular plane of the fundamental sphere. Based on the cutting motions the equations to describe tooth surfaces have been derived by using theory of gearing, and the equation of meshing of spiral bevel gears with spherical involute tooth surface is obtained in the text. This study can provide some fundamentals for manufacturing and contact analysis of spherical involute spiral bevel gears.

This paper involves a production system, which is composed of units (workstations) and buffers. The buffer is used to store semifinished and finished products in the production process, to reduce the impacts of bad equipment in the production system on the entire system performance. Considering the characteristics of the large number of components and the state of the buffers in the production system, this paper considers the influences of buffer states on upstream and downstream units. When using the availability as the allocation index and combining it with Markov theory, the production unit (workstation) and upstream and downstream buffers are regarded as an equivalent unit (workstation) with multiple output states. We establish the relationship between the availability of each equivalent unit (workstation) and the production system availability and determine a scaling factor for the availability of the equivalent unit to account for the system availability. The expected availability goal of the production system is allocated to each equivalent unit (workstation) by the scaling factor; then, the availability of each equivalent unit (workstation) is assigned to each unit. Finally, the Plant Simulation software is used to simulate and analyze the production system to verify the correctness of the allocation method and realize the reliability allocation from a complex production system to a unit.

Semi-solid powder forming (SPF) as a novel technology has been widely used to prepare composite materials. However, most of the present models used to simulate the complicated SPF process are based on the constitutive relationship of single dense or porous material, which cannot well satisfy the actual conditions. In this study, the process of semi-solid powder rolling was simulated by the combined constitutive formula of sintered and dense Al-Cu-Mg alloy materials obtained from semi-solid compression experiments. The results show that the semi-solid compression curves of dense and sintered materials are similar, and their peak stresses increase with the decreasing porosities. The grain or particle size of sintered materials after semi-solid compression becomes finer as powders crushed, but the grain size of dense materials becomes larger due to grain coarsening and deformation, which is the key advantage of SPF with fine microstructures. The combined constitutive model of semi-solid powder materials was established and verified, and then the numerical simulation of semi-solid powder rolling based on the model was proved that can well describe the rolling process, which provides a guidance for process optimization.

The present paper introduces an innovative strain energy function (SEF) for incompressible anisotropic fiber-reinforced materials. This SEF is specifically designed to understand the mechanical behavior of carbon fiber-woven fabric. The considered model combines polyconvex invariants forming an integrity basisin polynomial form, which is inspired by the application of Noether’s theorem. A single solution can be obtained during the identification because of the relationship between the SEF we have constructed and the material parameters, which are linearly dependent. The six material parameters were precisely determined through a comparison between the closed-form solutions from our model and the corresponding tensile experimental data with different stretching ratios, with determination coefficients consistently reaching a remarkable value of 0.99. When considering only uniaxial tensile tests, our model can be simplified from a quadratic polynomial to a linear polynomial, thereby reducing the number of material parameters required from six to four, while the fidelity of the model’s predictive accuracy remains unaltered. The comparison between the results of numerical calculations and experiments proves the efficiency and accuracy of the method.

Semi-solid powder rolling (SSPR) is widely used to produce alloy strips with fine grains and excellent performances in the automotive, aerospace and shipbuilding industries. During SSPR, powder temperature, as a very important parameter, greatly affects strips’ microstructures and mechanical properties, which have been investigated by many researchers, but its effect on the forming process and mechanism has rarely been studied. Therefore, based on online experimental detection and transient simulation, the microstructures, strip temperatures, relative densities and rolling forces at different conditions were, respectively, measured, calculated, compared and analyzed in order to study the deformation process and mechanism during SSPR. The result shows that with the increase in powder temperature, the strip temperature and relative density increase, while the rolling force decreases. The grains of the strips are refined after SSPR, and fine and dense microstructures are obtained at 600 °C, which is the optimum powder temperature. In the main deformation sections (II and III), when the contact normal force exists and reaches a maximum, the relative density and rolling force increase rapidly. At these sections, the strips rolled at 600 °C are mainly in a porous solid state, and powder crushing dominates the strip deformation. Therefore, SSPR at 600 °C and below can be considered porous or powder hot rolling, integrating powder crushing, solidification, deformation, densification and grain coarsening. Moreover, as the simulated values are basically consistent with experimental values, the thermomechanical coupling model based on the Fourier equation and its parameters are confirmed to be reasonable.