Applied Mechanics and Materials Vol. 575

Abstract: Disaster system of mine is a complex evolutionary process, and the nonlinear dynamics provides a good train of thought to solve such problems. Based on the introduction of nonlinear dynamics theory, this paper emphatically discusses the application of the theory in the geotechnical hazard prediction of mine. Finally it points out the problems existing in the study of nonlinear dynamics and the direction of the efforts.

Abstract: Rapid prototyping (RP) is a promising product development technology due to its unique characteristic of fabricating functional products timely and efficiently. Fused deposition modelling (FDM) process based on RP technology is used in industries for prototype fabrication and its properties testing. The properties of the RP fabricated prototypes such as wear strength, tensile strength, dimensional accuracy, etc. depends on the parameter settings of the RP machines. For selecting the appropriate parameter settings, various mathematical models developed based on physics and data can be formulated. In the present work, we introduced an ensemble method of genetic programming (GP) and artificial neural network for formulating a model for predicting the wear strength of the FDM fabricated prototype. The results indicate that ensemble model have performed better than that of the standardised GP, which may be then used by experts for optimising the performance of the FDM process.

Abstract: FEM analysis of MSC. Marc program is used to simulate the models. Three-dimensional FEM model with contact analysis between deformable body of specimens and rigid body of load are studied. The isotropic material and The Von Mises yield criterion are used and kinematic hardening is used as a flow plasticity model. The effect of various shapes of loading tips is investigated. The load-displacement were established. The results of these works are expected to be a useful reference for analyzing structures under various shapes of loading tips either static or dynamic loading.

Abstract: Kinematic chains differ due to the structural differences between them. The location of links, joints and loops differ in each kinematic chain to make it unique. Two similar kinematic chains will produce similar motion properties and hence are avoided. The performance of these kinematic chains also depends on the individual topology, i.e. the placement of its entities. In the present work an attempt has been made to compare a family of kinematic chains based on its structural properties. The method is based on identifying the chains structural property by using its JOINT LOOP connectivity table. Nomenclature J - Number of joints, F - Degree of freedom of the chain, N - Number of links, L - Number of basic loops (independent loops plus one peripheral loop).

Abstract: The effect of inner nozzle lip thickness on the co-flow jet characteristics has been studied experimentally. Co-flow nozzles with inner nozzle lip thicknesses of 3 mm and 15 mm have been investigated. The thick-lip nozzle promotes mixing better than the thin-lip nozzle, for all the underexpanded operating conditions. The co-flow nozzle with thin-lip is effective in preserving the shock-cells nature, bringing down the longer shock-cell into shorter one and increasing the number of shock-cells compared to that of the co-flow nozzle with thick-lip.

Abstract: The aim of this paper is to present an integrated procedure for the optimization of dimensions of the ITI dental implant with dynamic chewing loads. The procedure is composed of uniform design of experiments, explicit dynamics finite element analysis, Kriging interpolation, and Nelder-Mead simplex local search optimization method. Firstly, uniform design method is employed to create a set of experiments. Then, explicit dynamics finite element analysis software ANSYS/LS-DYNA is used to analyze the micromotion of cortical and cancellous bones while the dynamic chewing loads acts on the implant. Next, Kriging interpolation is applied to construct the surrogate model of micromotion based on the input and output data of experiments. Finally, Nelder-Mead simplex local search method is applied to find the optimal solution of dimensions of dental implant under the goal of minimizing the micromotion. After performing the optimization procedure presented in this paper, the micromotion of the ITI dental implant system model can successfully be reduced by a rate of 29.7 %.

Abstract: Die casting is a cost-efficient method of forming geometrically complex near net-shaped products with close tolerances and excellent surface finishes.Due to the thermal shock characteristics, a number of test methods have been proposed to understand thermal fatigue behaviours of the die material as real die casting dies experience.This study reveals the differences of these methods by numerical modelling the thermal behaviour of the test specimen. Simplified die casting process is firstlyproposed to facilitate numerical computation. Test specimens are then optimized to be more representative of a real die. From the comparison results, we can conclude that least divergence can be obtained between immersion tests and induction heating based tests while furnace heating based tests would result in low thermal shock effects on the test sample.

Abstract: Substructure of offshore modular drilling rig has complex loading. It is necessary that a 3D finite element analysis has been conducted by using finite element software for substructure. The distributions of integrated displacement and stress have been obtained. The results show that the axial strength and stiffness of the substructure are sufficient. The relevant evaluation methods were summarized and integrated into the finite element software, and the command flow program of post-processing is written. Through post-processing graphical display, the carrying capacity of substructure is presented. The results show that the carrying capacity of substructure can meet the requirements in the combination condition which contains the maximum rotary load and the maximum setback load. This research method can provide pertinent reference for carrying capacity assessment of steel structure, and have some practical significance for field operation.

Abstract: The positioning accuracy of CNC machine tool is the best moving position accuracy which the machine tool can reach under the control of CNC control system. The principles of frequency laser interferometer measurement are described in this paper, and pitch error is compensated by taking DAHE V1500 CNC machine with FANUC system as example. The result shows that the precision of CNC machine tool is effectively improved.

Abstract: According to Evaluation and Expression of Uncertainty in Measurement (JJF1059.1-2012), measurement error of each element sensor in automatic weather station will be in drift over time, temperature and other environmental factors. In order to ensure the accuracy, reliability of observational data of each element,in this paper,humidity calibration chamber provided environment, and precision dew-point transmitter as the standard device. The article has introduced the general methods and detailed procedures of how to use HMP45D temperature and humidity sensor for humidity measurement uncertainty evaluation.Finally,it gave an evaluation example.By analyzing and calculating the each component of measurement uncertainty,we got the expanded uncertainty of humidity is 1.50%RH and 1.46%RH, with temperature of 22degrees and 40degrees, 30%-75% relative humidity.