Shandong Special Equipment Inspection Institute

Jinan, China

Shandong Special Equipment Inspection Institute

Jinan, China
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Jin Y.,Shandong University | Wan Y.,Shandong University | Zhang B.,Shandong Special Equipment Inspection Institute | Liu Z.,Shandong University
Journal of Materials Processing Technology | Year: 2017

Fused deposition modeling has become one of the most diffused rapid prototyping techniques, which is widely used to fabricate prototypes. However, further application of this technology is severely affected by poor surface roughness primarily due to staircase effect. It is necessary to adopt post-treatment operations to improve surface quality. Chemical finishing is typically employed to finish parts in fused deposition modeling. The purpose of this paper is to provide a universal finishing method or solution for FDM parts made up of PLA, and to represent the evolution of surface topography between adjacent layers during the chemical finishing operation by building a geometrical model of the deposited filament. Case study was used to validate the proposed model by an experimental observation using a 3D laser scanning microscope. The comparison between theoretical computed values and observed data shows a significant reliability by means of statistical analysis. Subsequently a number of specimens are tested to determine the changes in tensile properties of fused deposition modeling parts building in different orientations. The results show that the horizontal build directions have little influence on the tensile strength. And, untreated specimens of polylactic acid show brittle behavior due to the inherent material properties. Because of the thin transparent film formed on the appearance, the tensile mechanical properties of specimens after chemical finishing are obviously changed, with the result that the tensile strength reduces by 63% and elongations at break improve by 50%. This chemical finishing not only decreases the roughness of parts manufactured in fused deposition modeling significantly, but also improves the toughness of polylactic acid parts. © 2016 Elsevier B.V.


Yu J.,Shanghai University | Yu J.,Xi'an Jiaotong University | Liu M.,Shanghai University | Wu H.,Shandong Special Equipment Inspection Institute
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2011

The sensitivity of various features that are characteristics of machine health may vary significantly under different working conditions. Thus, it is critical to devise a systematic feature selection (FS) approach that provides a useful and automatic guidance on choosing the most effective features for machine health assessment. This article proposes a locality preserving projections (LPP)-based FS approach. Different from principal component analysis (PCA) that aims to discover the global structure of the Euclidean space, LPP can find a good linear embedding that preserves local structure information. This may enable LPP to find more meaningful low-dimensional information hidden in the high-dimensional observations compared with PCA. The LPP-based FS approach is based on unsupervised learning technique, which does not need too much prior knowledge to improve its utility in real-world applications. The effectiveness of the proposed approach was evaluated experimentally on bearing test-beds. A novel machine health assessment indication, Gaussian mixture model-based Mahalanobis distance is proposed to provide a comprehensible indication for quantifying machine health state. The proposed approach has shown to provide the better performance with reduced feature inputs than using all original candidate features. The experimental results indicate its potential applications as an effective tool for machine health assessment.


Wu H.,Shandong Special Equipment Inspection Institute | Chen H.J.,Shandong Special Equipment Inspection Institute | Meng P.,Shandong Special Equipment Inspection Institute | Yang J.G.,Shanghai JiaoTong University
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture | Year: 2010

Cutting-force-induced errors are one of the major sources of error in numerical control (NC) machine tools. The error compensation technique is an effective way to improve the manufacturing accuracy of NC machine tools. Effective compensation relies on an accurate error model that can predict the errors exactly during the machining process. In the present paper a robust and accurate cutting-force-induced error model is built using a backpropagation (BP) neural network and a genetic algorithm (GA) for an NC twin-spindle lathe. The GA-BP neural network modelling technique not only enhances the prediction accuracy of the model but also reduces the training time of the BP neural network. A real-time compensation system of the cutting-force-induced error on the lathe is developed based on the cutting-force-induced error model. The errors were reduced by about 38 per cent after real-time compensation in a machining experiment. © Authors 2010.


Zou B.,Shandong University | Ji W.,Shandong University | Huang C.,Shandong University | Xu K.,Shandong University | Li S.,Shandong Special Equipment Inspection Institute
International Journal of Refractory Metals and Hard Materials | Year: 2014

Strength retention is important for tool materials at high temperature because cutting temperature in machining is ranged from room temperature to 1000 °C. A study examining the strength properties and fracture behaviour of TiB2-TiC-based composite ceramic cutting tool materials is presented at different temperatures. MoSi2 and SiC additives are considered to investigate their effects on the density, microstructure, strength and failure mechanism of composites. It is found that the addition of SiC contributed more to the high-temperature strength of composites than MoSi2, but it did not improve the room-temperature strength, despite grain refinement. The TBAVS8 composite has a flexural strength of 800 MPa at room temperature and can retain 75% at 900 °C. At room temperature, the fracture behaviour of composites was dominated by the strong bonding of the Ni binder phase. At high temperatures, the softer Ni binder phase was pinned, and its sliding was inhibited by SiC particles, which decelerated the strength degradation. © 2014 Elsevier Ltd.


Zou B.,Shandong University | Ji W.,Shandong University | Huang C.,Shandong University | Wang J.,Shandong University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

A study to increase the mechanical properties of TiB2- TiC+Al2O3 composite ceramic cutting tool material by using superfine refractory carbide additives is presented. Four superfine refractory carbides are considered to investigate their effects on the phase composition, element distribution, grain size, fracture surface, crack propagation of the metal ceramic. The physicochemical properties of superfine carbides, such as chemical activities and atom radius, were found to have the significant effects on the microstructure and mechanical properties of the metal ceramic. Hafnium carbide (HfC) and Tantalum carbide (TaC) reduced the mechanical properties of the metal ceramic because of their poor solubility with the Ni binder phase and the formation of oxides. The mechanical properties of the metal ceramic were increased by the addition of superfine niobium carbide (NbC) and vanadium carbide (VC), and their optimum values were a flexural strength of 1100 ± 62 MPa, fracture toughness of 8.5 ± 0.8 MPa.m1/2 and hardness of 21.53 ± 0.36 GPa, respectively, when 3.2 wt% superfine VC was used. © 2013 Elsevier B.V. All rights reserved.


Zou B.,Shandong University | Ji W.,Shandong University | Huang C.,Shandong University | Li S.,Shandong Special Equipment Inspection Institute | Wang J.,Shandong University
International Journal of Refractory Metals and Hard Materials | Year: 2014

TiB2-TiC laminated Ti(C5N5) composite ceramic cutting tool materials are prepared at the argon and vacuum sintering atmospheres respectively. The microstructure and mechanical properties of the composite are investigated. It is found that the composite includes the bulk and surface layer before sintering, while the new diffusion and transitional layers are formed after sintering. The Ni binder phase is rich in the diffusion layer, and the diffusion layer of the composite sintered at the vacuum atmosphere is narrower. The formation of layers is driven by the outward diffusion of the N element which results in the depletion of carbo-nitrides and the flowing of the melting Ni phase during the sintering. The composite exhibits the higher flexural strength and surface hardness than the monolithic Ti(C 5N5) material. The Ni-rich diffusion layer acts as a tough subsurface in the composite, which can strengthen the effect of grain pulling-out as well as absorb the crack propagating energy. The flexural strength of the composite sintered at the vacuum atmosphere is slightly higher than at the argon atmosphere, while there are no obvious differences in the hardness and fracture toughness between these two composites. © 2013 Elsevier Ltd.


Zou B.,Shandong University | Zhou H.,Shandong University | Xu K.,Shandong University | Huang C.,Shandong University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

Various ratios of superfine WC and TaC particles were added into Ti(C 7N3) matrices, and Ti(C7N3)-based composite cermets tool materials were prepared using a hot-pressed sintering technology by various processes. The effects of the superfine WC and TaC particles and sintering processes on the mechanical properties and microstructure were thoroughly investigated. The addition of superfine WC depressed the mechanical properties, but the addition of superfine WC and TaC together refined the microstructure, which optimised the mechanical properties of materials. Both a longer holding time and a higher sintering temperature facilitated the growth of (Ti,W,Ta,Mo)(C,N) grains that caused a reduction in the flexural strength and fracture toughness. A Ti(C7N 3)-based cermets tool material with a 9 wt% WC and a 6 wt% TaC, which is sintered at 1400 °C with 30 min at 30 MPa, exhibits the best mechanical properties. This cermet material was then manufactured into cutting tools which maintained good wear resistance after 85 min of high-speed cutting stainless steel. © 2014 Elsevier B.V. All rights reserved.


Zou B.,Shandong University | Huang C.,Shandong University | Ji W.,Shandong University | Li S.,Shandong Special Equipment Inspection Institute
Ceramics International | Year: 2014

A study of the effects of Al2O3 and NbC additives on the microstructure and mechanical properties of TiB2-TiC composite ceramic cutting tool materials is presented. The relations of the room temperature and high-temperature mechanical properties to the microstructure of the composite were investigated. The Al2O3 additive was determined to slightly increase the flexural strength and fracture toughness of the composite at room temperature and significantly increase the flexural strength of the composite at high temperatures. The superfine NbC additive improved the room-temperature flexural strength of the composite by approximately 30%. The microstructure was refined, and the resultant mechanical properties were improved if Al2O3 and NbC were added to the composite together. The flexural strength of the TiB2-TiC+Al 2O3+NbC composite material still exceeded 500 MPa at 800 C, which can meet the demands of cutting tool materials. The quick degradation of the high-temperature flexural strength of the composite above 800 C was mainly due to the softening of Ni binder phase. © 2013 Elsevier Ltd and Techna Group S.r.l.


Zhao Y.,Shandong Jianzhu University | Song M.,Shandong Special Equipment Inspection Institute
Engineering Failure Analysis | Year: 2016

A L390 natural gas pipeline exploded in 2011 in China. Macrofracture examination, thickness measurement, chemical composition analysis, metallographic inspection, mechanical property testing, fracture scan electronic microscopy examination and environment analysis were conducted to the burst pipeline. The results showed that Stress Corrosion Cracking (SCC) generated in the mechanical damaged zone of the pipeline was the reason of the failure. This kind of cracking was induced by Cl- and HCO3 - in near neutral corrosive medium of pH value. The stress concentration was induced by the groove damage under inner pressure. © 2016 Elsevier Inc.


Zhao Y.,Shandong Jianzhu University | Song M.,Shandong Special Equipment Inspection Institute
Advanced Materials Research | Year: 2013

Effect of the energy density on the composition, morphology and deposition rate of the bioglass thin films deposited by pulsed laser was studied by energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and crystal lattice monitor. There is slight compositional difference between the film and the target at lower energy density. Morphology of the films is compact with the particles on the surface of them. Structure of the films is amorphous glass and the size of the particles increases with the energy density. Deposition rate increases with the energy density and the energy density threshold of the film growth is about 2.5J/cm2. © (2013) Trans Tech Publications, Switzerland.

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