Applied Mechanics and Materials Vols. 548-549

Abstract: In order to study the maximum strain of steel shell surface under the impact of a falling ball, a thin shell model and the strain time history curves of impact are achieved by ANSYS/LS-DYNA. A deformation behavior of the shell was calibrated from the test which uses a ball free fall and some resistance strain gauges pasted to the inner surface of an iron shell box. The gauges are connected as inputs to a Wheatstone bridge circuit and an Oscilloscope is used to observe the output. The results show the impact test and ANSYS/LS-DYNA simulation results are smoothly consistent with the strain of the test at the maximum strain amplitude of the model, and the maximum difference is 9.5%. Accurate results can be achieved by combining the test method and the simulation approach as an industrial application.

Abstract: As a ship of high technology content, dredger is equipped with a very important structural part—spud. In actual working condition, spud is affected by seabed terrain and force of sediment. Moreover, water flow and wind will impact the hull. Consequently, the effect of moment of force on the hull’s center of gravity will cause heeling of the hull. This paper, with the help of geometrical relationship, is to quantificationally analyze and calculate the influence of transverse, longitudinal sloping and ordinary heeling on the underwater positioning accuracy of clamshell in the condition of heeling. Then it offers relevant compensation, in order to reduce the accuracy error of clamshell’s underwater positioning caused by hull’s heeling.

Abstract: A finite element model of rock mass under linear conical shaped charge liner including explosive, metal liner, air and rock mass is built. The ALE algorithm is applied to simulate the penetration characteristic of rock mass and analyze the influencing factors such as the cone angle, the wall thickness of metal liner, and the standoff distance. Fluid-structure coupling condition is used between metal liner and air as well as between air and rock mass. The present results show that LS-DYNA can be well used to simulate the progress of jet formation and rock penetration with the transmission and focusing of shock stress wave. The different cone angles, wall thicknesses of the metal liner, and the standoff distances will influence the penetration effect.

Abstract: One of the effective ways to improve the efficiency of cutting tools is the use of innovative types of multilayer coatings combining friction properties and high wear resistance. The object of study of this work was to investigate the influence of the composition of sublayer with anti-friction properties like component functional multilayer coatings on tool life. The data obtained in these studies were the basis for the development of the concept of functional multilayer coatings for cutting tools with programmable properties, providing an opportunity for each coating layer to perform a required function at a certain stage of tool wear. As used HSS substrate which is preliminarily subjected to ion nitriding by glow discharge and in addition alloyed gas-metal ions before coating deposition. The final step involved coating deposition process TiCrN using filtered cathodic vacuum arc deposition (FCVAD). Studies have shown that mixing the antifriction alloys which are widely used to improve friction properties allow to increase the tool life is not more than two times. This method of the tool life increase by reducing the shear strength of boundary adhesion between the tool and the work material does not seem to be the most effective for multilayered coatings under analysis, as for almost all studied anti-friction materials, the adhesion between the coating and the modified surface was rather low. This precludes their practical application due to technological reasons. Implantation the chemical elements can achieve much better results. Elements such as indium, silver and nitrogen increase tool life in 2 - 3 times for different cutting conditions (using dry cutting or cutting with cutting fluid). The obtained results can be considered as the most promising. Indium and silver are interactive with respect to Fe and may be used as lubricants in metal and promote a crushed chip forming at cutting using coating under the study. Ion surface modification of the tool with other studied elements demonstrates unstable or negative results that reduction in tool life or inability to provide good adhesion between the coating and substrate.

Abstract: This paper aims to reveal the mechanical effects of metal holder and bolt (anchor) in anchor frame combination structure, then shows existing problems of anchor frame combination supporting structure being used in present coal mine, and gives corresponding solution on the basis of modern mechanics theory. By specify examples and on the basis of having administered the pull test of bolt (anchor), the article has calculated and analyzed the stress distribution rule of metal holder in anchor frame combination supporting structure according to the statically indeterminate principle in solid mechanics. In contrast to single metal holder structure, the consequence comes to be that the bearing capacity was significantly increased. However, the actual stress values of bolt (anchor) in field measurement shows that the bearing capacity of bolt (anchor) has hot been given full work. So the essay not only reveals the good bearing capacity of anchor frame combination structure but also points out that there is plenty of scope for optimization in anchor frame combination structure, and its research results have a certain reference for supporting theory and technology research in deep level and high ground pressure soft rock roadway.

Abstract: Volume fracturing is the key technology that has made the development of tight oil formations economical. Well testing is often used to obtain formation parameters in oil field after volume fracturing in tight oil formations, which is time-consuming and accuracy is low. Based on a new analytical solution methodology, this paper presents a simple and efficient approach by matching the production data to obtain formation parameters, just like formation permeability, fracture conductivity, dimensionless conductivity, propped length and so on. The numerical solution is applicable for finite-conductivity vertical fractures in rectangular shaped reservoirs. The mathematical formulation is based on the method of images with no flow boundaries for symmetrical patterns.

Abstract: In this paper, the multi-pulse chaotic dynamics of a simply-supported symmetric cross-ply composite laminated rectangular plate with the parametric and forcing excitations is investigated by using the extended Melnikov method. The two-degree-of-freedom non-autonomous nonlinear dynamical system of the plate with strong coupling is considered. The results obtained here indicate that multi-pulse chaotic motions can occur in the plate. Numerical simulation is also employed to find the multi-pulse chaotic motions of the plate based on the theoretical analysis.

Abstract: Circumferential cracking occurred on the spoke plate of a statically placed marine gear. Fractographic investigation indicates that two independent crack origins are present on the fracture surface. Intergranular fracture mode was mostly found in slow crack propagation region and the intergranular facets associated with ductile shearing. Metallographic observation reveals that a type of macro casting defect, spot-segregation, is generally present on the gear material. Large size macro spot-segregation defect zones just appear in two crack origin regions. Appearance of the large spot-segregation zones in the core of spoke plate supplies the favorable metallurgical condition for hydrogen-induced fracture: presence of excessive impurities of S, P and then appearance of abnormal microstructure of upper-bainite susceptible to hydrogen embrittlement. From the evidences it is concluded that the gear failed due to the hydrogen embrittlement. The possible source for hydrogen was introduced during melting and casting operating.

Abstract: Tower crane hoisting system is the most important structural component of tower crane components. Its structural performance directly affects the performance of the overall tower crane. Combining the characteristics of The unconventional dedicate tower crane, established the mathematical model of hoisting system, and complied the particle swarm optimization algorithm program based on improved particle swarm optimization algorithm by MATLAB language, optimized analysis of hoisting system of The unconventional dedicate tower crane, and verified the optimization results by static analysis in the end. The result shows that the optimized analysis of tower crane hoisting system is viable and efficient by the improved particle swarm optimization algorithm.

Abstract: For the problem of balance bearing of universal spindle in rolling mill being prone to damage, the paper established mechanical model and finite element model of universal spindle. The paper has analyzed that the shear and bending moment in the middle of the shaft is the largest. The fillet near shoulder of balance bearing of the spindle is dangerous part. In order to reduce principal stress of universal spindle caused by moment, the paper improved balance mode of the spindle. The equilibrant was applied from in one place of shaft to put in two places. After optimizing, equivalent stress of the spindle is slight smaller than before under the same loading condition, which illustrates that the strength of the spindle is appropriately improved. Although the effect is not obvious, this has played a guiding role for the optimization of balance mode of universal spindle.