Applied Mechanics and Materials Vols. 239-240

Abstract: New mode of measurement and draft in mechanical drawing based on reverse engineering is presented to reflect the idea of modern engineering design on teaching practice. Traditional measurement tools are replaced by three-dimensional scanner, whereas graphics processing is performed by using CAD technology. The processing includes three steps. Firstly, point cloud of part surface shape is obtained through scanning. Secondly, point cloud images are joined, filtered and latticed in Geomagic, which is application software of CAD. Finally, the processed point cloud is imported into Catia to reconstruct surface and three-dimensional geometric model. An innovative method of measurement and draft is accordingly proposed, which combines teaching and practices and helps to cultivate the innovative idea and abilities of students.

Abstract: Drilling-Hole-Loading method is applied to predicting and measuring the tensile strength of irregular small-size stones. According to this method, a circular-hole must be drilled at the center of the irregular small-size stone. The mechanical model of the stone with a circular-hole and subjected to a pair of equivalent collinear pull forces is set up. The normal stress strain distributions on the critical section are anlyzed. Theoretical stress concentrated factor equation related to the hole diameter is calculated. Based on the static equilibrium theory, the theoretical formula of predicting the tensile strength of irregular small-size stones is established. Based on the theoretical formula, the test device for measurement of the tensile strength of the stone was designed. The tensile strength of a kind of bluestone was measured. The results show that the tensile strength predicted by Drilling-Hole-Loading method is a little lower than that of the standard specimen of stone without hole. Drilling-Hole-Loading method can be used to predict the tensile strength of brittle material and irregular small-size stones.

Abstract: This paper takes the short and medium span bridges as examples to evaluate position of Chinese load effect partial safety factors and their combination effect. First, to get the new partial safety factors of vehicle load effects, this paper conducted a survey of the short and medium span bridges ,distinguished the similarities and differences between the standard in highway bridges from different countries and confirmed the reasonable position of Chinese standard in the world.

Abstract: The aim of this research is to investigate the relation between the surface roughness and the dynamic cutting force ratio during the in-process cutting in CNC turning process. The proposed surface roughness model is developed based on the experimentally obtained results by employing the exponential function with five factors of the cutting speed, the feed rate, the tool nose radius, the depth of cut, and the dynamic cutting force ratio. The dynamic cutting force ratio is proposed to predict the surface roughness during the cutting, which can be calculated and obtained by taking the ratio of the corresponding time records of the area of thedynamic feed force to that of the dynamic main force. The in-process relation between dynamic cutting force ratio and surface roughness can be proved by the frequency of the dynamic cutting force which corresponds to the surface roughnessfrequency. The multiple regression analysis is utilized to calculate the regression coefficients with the use of the least square method at 95% confident level. The proposed model has been verified by the new cutting tests. It is understood that the developed surface roughness model can be used to predict the in-process surface roughness with the high accuracy of 90.3% by utilizing the dynamic cutting force ratio.

Abstract: A new method for multi-axle moving train loads identification on continuous bridge is presented in this paper. In order to improve the accuracy and efficiency for moving loads identification, both cubic spline interpolation technique and dynamic displacement influence line technique were employed. The time history displacements of the measurement stations under unit force were calculated with cubic spline interpolation technique based on the finite element model of the bridge. The dynamic displacement influence line was obtained to be used for identifying the moving train loads with simulated annealing genetic algorithm by minimizing the errors between the measured displacements and the reconstructed displacements from the moving train loads. A series of comparative studies were carried out to investigate effects of different span numbers with the same length, different length with the same span number and measurement noise on the proposed method. The result shows that the proposed method is an accurate and efficient method for multi-axle moving train loads identification on continuous bridge.

Abstract: Motor vehicle’s controllability and stability were its fundamental performances, of which the steady state circular test (i.e. SSC) was most important, and become the basis of motor vehicle’s dynamics stability control. In this paper, two group of typical SSC data of one motor vehicle were employed and processed by the graphical programming language LabVIEW software, then the curves (Ri/Ro)-ay, (1-2)- ay and - ay were obtained. According to the curve analysis and related rules and regulations, the lateral acceleration of neutral steering an, understeering gradient U, and the vehicle body rolling rigidity K were resolved, so we could get the motor vehicle’s SSC performance comprehensive evaluation value. The work in the paper constructed a platform for vehicle’s controllability and stability study conveniently and efficiently.

Abstract: This paper introduces the hardware components of the straightening force measuring system for the pre-stress straightening machine firstly. Then finite element analysis is made for the frame of pre-stress straightening machine based on ANSYS Workbench. Relationship between the straightening force and relative strain on the column neutral layer is obtained by using polynomial fit. And this relationship is used to obtain straightening force in the DAQ software. Then the straightening force DAQ software is developed based on LabVIEW. Structure and development process of the software are introduced in details at last.

Abstract: The spindle wheel forces load spectrums of certain car were collected on typical service roads and proving ground roads. Rain-flow matrixes of wheel forces in target service roads and proving ground roads were analyzed based on measured load spectrums with analysis software. Then different roads of proving ground were combined to simulate target service roads with load equivalent analysis method based on rain-flow matrixes. The damages were compared between target service roads and combined roads in proving ground. The results show that the combined roads in proving ground can reflect the true damage of the target service roads.

Abstract: Automotive door must have adequate stiffness as the important component of an automobile. In this paper, firstly, bending stiffness, torsional stiffness and sinking stiffness of an automotive door were simulated, got the deformation curves of the door in the three conditions. Then an experiment was used to verify the result of finite element analysis. These two methods complemented each other. The stiffness of the door was studied and analyzed by two methods, provided a reference for the improvement of the door.

Abstract: In bio-medicine and other fields, shape analysis is very important for diagnosis of diseases and prediction of shape variation. This paper focuses on the surface parameterization of tube-like 3D objects to obtain and analyze shape information from a sample shape, including its size and the shape variation between different samples. It can well represent the global and local shape information for statistical analysis and for the construction of Medial Shape Model. Firstly, we extract the axis curve of the object by a heat conduction model. Secondly, we obtain the latitude circles by using the normal planes to cross the surface. Then we get the final parameterized surface with quad-dominant meshes by registering the points of single latitude circle and between different circles through coordinate transformation and alignment. Subsequently, we apply the approach to parameterization of a rib bone.