Abstract: In view of the heavy dump truck occurred cargo body floor cracking problems in the process of using, this paper established cargo body finite element analysis (FEA) model with the shell elements as basic element, and calculated the strength of the cargo body floor by using the Hyperworks (a FEA software). The results of finite element analysis indicate that the crack took place because the stress of the connection of floor and support beam of front plate and the connection of floor and backing plate of turnover bearing was close to or exceed the material yield strength. On the basis of the calculation, we worked out the causes of the abnormal floor crack, which accord with the actual crack case. According to the requirement of practical process, the structure of floor was improved, thus the maximum stress value decreased 30% and 80.9% at two positions respectively, compared with the original structure, this shows that the improved method is effective.
Abstract: This paper studies the mechanical performance of fiber carbon composite core rod under coiled condition by finite element simulation and analyzes the failure modes by coiling test, providing technical support and theoretical basis for the manufacture technique, test method, and application of fiber carbon composite core rod.
Abstract: A viscous fan clutch with double grooves is taken as a studying example for measuring its slip and surface temperatures. The grooves between driving and driven plate of the viscous clutch are filled with silicone-oil in this study. Experimental methods and test rig to measure the slip and surface temperatures for a viscous clutch are discussed. The relations of the clutch slip and clutch surface temperatures with the change of the input speed are measured.
Abstract: To study the failure process of metal structure with meso-defects, RVE (representative volume element) with various initial meso-defects were analyzed by using ABAQUS software, the parameter f (void volume fraction) of GTN damage model was regarded as the criterion of structural damage. The result shows that f increased more obvious with volume of defects for spherical defects with the same shape but different size. When the radius of defects is less than 0.15mm, the influence of defects’ volume on increases of f is clear enough. When the radius is greater than 0.15mm, the effects is diminishing. For ellipsoidal defects with the same volume but different aspect ratio, when the long axis perpendicular to the direction of load, the increased trend of f according to plastic deformation more obvious along with aspect ratio of defects. Apparently, as aspect ratio approaches infinity, f would have the fastest growth. Consequently, the bigger defect volume and aspect ratio, the more conducive for damage evolution of the metal structure.
Abstract: The impact responses and ballistic resistance of the metal encapsulating ceramic composite armors with same area density and two hybrid cores are investigated. The hybrid cores include square metallic lattice with ceramic block insertions, and square metallic lattice with ceramic ball insertions and void-filling epoxy resin. Three-dimensional (3D) finite element (FE) simulations are carried out for each composite armors impacted by bullet with 12.7mm diameter. The focus is placed on the energy absorption capabilities and ballistic limit velocity of different composite armors. Results indicate that two kind of armors can improve the ballistic resistance properties and save mass of 22% and 25% compared to the homogeneous 4340 steel, respectively.
Abstract: The selection of absorber parameters is of utmost significance for structural vibration control by dynamic vibration absorbers. Based on the classical frequency tuning approach by Den Hartog, optimal damping ratio is derived in close form by equating the dynamic magnification factors of the structural motion at three particular frequencies of interest. In addition, by maximizing the two identical modal damping ratios through root locus in the first quadrant of complex plane, the corresponding absorber damping ratio is derived and proposed as the upper bound of the absorber damping ratio for practical applications.
Abstract: Wubei-Xiaohuangshan railway was characterized by the large local temperature difference, and high density of heavy haul train traffic. Reasonably determining the rail stress-free temperature has an important role on the line traffic safety and stability. Combined with the actual situation of the line, this paper researched some key technical issues of laying CWR in alpine and large temperature difference region, from determining the reasonable allowable temperature rise, allowable temperature drop, the rail stress-free temperature, and its allowable ranges, etc. Look forward to give some reference to the similar engineering problems.
Abstract: This paper analyzes the performance of fiber carbon composite core rod under torsion load through finite element simulation and full-scale test, providing technical basis for the failure mode and key parameter design of fiber carbon composite core rod.
Abstract: In this paper, overlaid cement concrete pavement with crack is considered based on fracture mechanics. Cement concrete pavement is reduced to an elastic plate on Winkler foundation. Fourier integral transform, residue theorem and Lobatto-Chebyshev integration formula are used to obtain the analytical solutions of this problem. To analyze the effect of overlay for the old pavement, stress intensity factors ofItype crack and II type crack are calculated respectively for various overlay thicknesses, elastic moduli of the overlay. The stress intensity factors of the crack tips in the pavement with 10cm thickness overlay are reduced heavily. However, stress intensity factors are less affected by elastic modulus of overlay material.