Purpose A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental data and the theoretical foundation for LS of pine/co-PES, especially for the application of using the laser-sintered pine/co-PES parts as complex structural patterns in investment casting. Design/methodology/approach The PCPES composites with different pine loadings were mixed mechanically. The composite’s preheating temperature and processing temperature during LS were determined experimentally based on the material’s thermal behavior. The effects of pine powder on the binding mechanism of PCPES composites were discussed through analyzing the microstructure of the laser-sintered parts’. Mechanical properties and dimensional precision of laser-sintered PCPES parts in different pine loadings were tested, and the parts’ mechanical properties were strengthened by wax-infiltration post-processing. The influence extents of process parameters on the mechanical properties of laser-sintered 20 Wt.% pine/co-PES parts were investigated using a 1/2 fractional factorials experiment. Findings 20 Wt.% pine/co-PES is considered to be a promising wood-plastic composite for laser sintering. The relationship between mechanical strength of its laser-sintered parts and process parameters was built up using mathematical formulas. Experimental results show density, tensile strength, flexural strength and surface roughness of laser-sintered 20 Wt.% pine/co-PES parts are improved by 72.7-75.0%, 21.9-111.3%, 26.8-86.2%, 27.0-29.1% after post-process infiltration with a wax. A promising application of the wax-infiltrated laser-sintered parts is for investment casting cores and patterns. Research limitations/implications The proper process parameters and forming properties of laser-sintered parts are limited to the results of laser sintering experiments carried on using AFS 360 rapid prototyping device. Originality/value This investigation not only provides a new feedstock for laser sintering with the advantages of low cost and fabricability but also uses an advanced technique to produce personalized wood-plastic parts efficiently. Mathematical models between mechanical properties of laser-sintered PCPES parts and LS process parameters will guide the further LS experiments using the 20 Wt.% pine/co-PES composite. Besides, the laser-sintered PCPES parts after wax-infiltration post-processing are promising as complex structural patterns for use in investment casting.

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The optimum material gradient of a rectangular plate made of functionally graded material (FGM) is determined in this study. Elastic modulus of functionally graded (FG) rectangular plate is assumed to vary continuously throughout the height of the plate, according to the volume fraction of the constituent materials based on the power law, exponential model I, exponential model П, or sigmoid functions. The difference between these distribution functions for the constituents’ volume fraction is discussed in this study. To determine the optimum material gradient of a rectangular plate made of FGM, the finite element method and the optimization techniques are used. In this study, von Mises stress, shear stress, and deformation in FGM case with the power law, exponential model I, exponential model П, or sigmoid functions are investigated. Simulation results indicate that the optimum material gradient for FG rectangular plate can be described by using a modified sigmoid function. The maximum values of von Mises stress, shear stress, and deformation in FG rectangular plate with the optimum material gradient are reduced compared with the pure material case by around 22%, 11%, and 24%, respectively.

The quality loss caused by tolerance of factors can be reduced when the nominal values of design-factors are carefully chosen. Therefore, the parametric optimization method is significant to an optimally define the Quality Loss cost (QLc). In this work, the Design Exploration (DE) and Taguchi Methods along with unforced Rotordynamic analysis have been used to find the optimal levels of factors affecting the QLc. Under definite constraints, the mathematical models are developed for an optimization problem and then utilized to develop Machine Motorized Spindle (MMS). In order to find the optimal levels of the factors, the sensitivities of factors on structural weight and First-Order-Nature-Frequency (FONF) has been analyzed using Response-Surface (RS) method, while the Taguchi method is used to find the QLc. The results found shown that there are significant enhancements in signal-to-noise ratio for structural weight and FONF. The QLc has been saved to about more than half-time by comparing to its initial values. The results also indicated that the proposed optimization approach is feasible and successful in improving dynamic characteristics and QLc saving for the MMS. Keywords: Machine Motorized Spindle, Finite Element Method, Unforced Vibration, Rotordynamic Analyses, Response Surface Method, Taguchi Quality Loss cost.

Due to rapid development in the industry, operating speeds and eccentricity produced undesirable vibrations which may lead to damage in bearings, seals, and lubrication systems. In the proposed paper, a novel analytical method was presented using an integrated multi-body dynamics and finite element analysis to simulate the lateral and torsional vibration. This method was applied to a proposed model of single rotor-system. In order to study the lateral and torsional vibration of the system profoundly, three markers were placed on the locations of the left and right bearings and the mass center of the shaft. The effects of bearing force caused by lateral and torsional vibrations were also analyzed. The results showed that the lateral vibration has a great effect on the dynamic of single rotor-system when lowering motor speed. It was found that, as motor speed increased, the motion of the system becomes more stable with steady fluctuates of the displacement response. The calculated natural frequency of SRS is compared with theoretical results to verify the transient solver. This novel method is practical in analyzing the lateral and torsional vibration of the SRS under various speeds and eccentricities.

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In recent years, diesel engine is developing rapidly in the direction of high power and super long stroke, which requires higher strength of its key moving parts. Connecting rod is one of the key moving parts of diesel engine which is subjected to complex alternating load during the working process. This loading condition has a great influence on its structural strength and reliability. In the proposed study, the strength and fatigue of a low-speed diesel engine con-rod made of 42CrMoA are analyzed. The 3-D model of the con-rod assembly built in the proposed study. The stress distribution and deformation of the con-rod assembly under the maximum explosive pressure are presented and studied. In the present paper, fatigue safety factor of all parts of con-rod assembly under the maximum explosive pressure condition is checked. According to the results carried out from the proposed work, the corresponding alternating stress is 340MPa, while the fatigue limit of 42CrMo material is above 430-540MPa, which means that the con-rod parts work under the alternating stress far below the fatigue limit. The kirasushvili method is adopted in the present paper as the standard of safety factor evaluation of con-rod. According to the allowable safety factor table of kirasushvili method, the minimum safety factor of the big and small ends of the con-rod and rod body can meet the requirements without fatigue damage.

A machine-tool structure optimization is an important technique that improves the machining efficiency and saves materials and the energy resource. In this work, dynamic design optimization method for Machine-Motorized-Spindle (MMS) subjected to a number of rotating unbalanced forces effects is presented. Linear forced-Rotordynamic analysis with design explorer method has been used to simulate the output response. The Design Variables (DVs) and their limits were carefully chosen and applied to develop the Design-of-Experiment (DOE). The Box-Behnken Design (BBD) method, because of its good organization in providing much information in a minor number of required statistical experiments was used to generate the DOE. The influences of DVs on the dynamic of MMS and their levels optimization were evaluated by utilizing the Response-Surface (RS) method. The results showed that the spindle shaft inner diameter of the motor-rotor seat and its rotating unbalanced mass, and modulus of elasticity have the highest contribution in effect on the dynamic of MMHS. As well, it is found that the proposed optimization method not only improves the structural weight of MMS, but also the potential saving can be achieved in term material and energy resource.