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To reduce the mass of mechanical elastic wheels, the lightweight analysis was conducted by the finite element analysis software of Abaqus. Considering the bending moment load and radial load conditions of the wheels at all times, the finite element model of mechanical elastic wheels was established, and the finite element simulation analysis was carried out. The force data of the nodes were extracted from the simulation results to determine the load of wheel hub and hinge group. The weighted variable density method was used to optimize the topology of the hub and hinge group of mechanical elastic wheel, and the 3D model was reconstructed after optimization. The results show that the mass values of the optimized mechanical elastic wheel, wheel hub and hinge assembly are reduced by 15.1%, 27.9% and 22.6%, respectively. [ABSTRACT FROM AUTHOR]

BACKGROUND: In the treatment of osteoporotic vertebral compression fracture, bone-filling mesh container has a significant curative effect. Considering the operation time, lateral leakage of bone cement and the number of radiation exposure, unilateral approach is better. However, no study compared unilateral bone-filling mesh container and bilateral bone-filling mesh container from the perspective of biomechanics, lacking certain theoretical data support. OBJECTIVE: To investigate the biomechanical characteristics and clinical effects of unilateral and bilateral bone-filling mesh container approaches in the treatment of osteoporotic vertebral compression fracture. METHODS: (1) A finite element model was established to simulate the treatment of osteoporotic vertebral compression fracture with unilateral and bilateral bone-filling mesh container. The displacement and stress changes of the whole finite element model of thoracolumbar segment in the unilateral bonefilling mesh container group and bilateral bone-filling mesh container group were compared and analyzed under 400 N vertical downward loading force and 7.5 N·m bending moment load under four working conditions. (2) A retrospective analysis was performed on 99 patients with osteoporotic vertebral compression fracture who were treated with bone-filling mesh container from January 2018 to August 2020 in Wuhan Puren Hospital. Of them, 49 patients were treated with unilateral bone-filling mesh container and 50 patients were treated with bilateral bone-filling mesh container. Bone cement leakage rate, visual analogue scale score, and Cobb angle change were analyzed between the two groups. RESULTS AND CONCLUSION: (1) Finite element model: There was no significant difference in the maximum displacement between unilateral group and bilateral group under axial, forward flexion, left bending, and left rotation conditions (P > 0.05). There was no significant difference in the maximum stress between unilateral group and bilateral group under axial, forward flexion, left bending, and left rotation conditions (P > 0.05). (2) Clinical trial: The bone cement leakage rates in the unilateral and bilateral approach groups were 12% and 16%, respectively, and the visual analogue scale score and scoliosis angle at 6 months after surgery were significantly improved compared with those before operation in both groups (P < 0.001). There was no significant difference in visual analogue scale score and scoliosis angle between the two groups at 6 months after operation (P > 0.05). (3) From the perspective of biomechanics and clinical efficacy, unilateral bone-filling mesh container approach is more effective than bilateral bone-filling mesh container approach in treating osteoporotic vertebral compression fracture. [ABSTRACT FROM AUTHOR]

PE pipeline is widely used in urban gas pipe network. The carrying capacity of PE pipe with local thinning defects is an important means to ensure its safe operation.Firstly, the initial elastic modulus and yield stress are fitted by the finite element method to obtain the carrying capacity of internal pressure, bending moment and axial force, the BP neural network model including relative depth C/T, relative axial length 2A/√RT, relative circumferential angle 2θ/π and dimensionless parameters c, and combined with GA optimized BP neural network model. It can be found: the predicted value of the model is relatively consistent with the simulation results, which shows that the method of GA optimization of the BP neural network model is feasible,which provides an effective method for the intelligent safety evaluation of the PE pipeline with local thinning defects. [ABSTRACT FROM AUTHOR]

BACKGROUND: Human bones are characterized by strong nonlinearity and uneven bone distribution. Different elastic modulus assignments lead to great differences in static results. OBJECTIVE: To analyze differences of the three material attribute assigning methods in the numerical simulation analysis of vertebral body. METHODS: Based on the principle of reverse engineering, lumbar L4, L5 and intervertebral disc models were established through image segmentation, and three material attributes were assigned to the vertebral body models: (1) Gray value assignment: Gradient value was assigned by using gray value through Mimics. (2) Homogeneous and gray value mixed assignment: A single elastic modulus was given to the anterior cortical bone of the vertebral body, and gray values were used to give to the cancellous bone of the front end and the pedicle, transverse process and spinous process of the posterior end. (3) Cortical bone and cancellous bone assignment: Two elastic moduli of cortical bone and cancellous bone were used. The finite element model under the three assignment methods was loaded with an axial load of 100-500 N. The bending moments of 2, 4, 6, 8, and 10 N·m were applied to simulate the vertebral body to perform forward flexion, backward extension, left and right lateral bending and left and right rotation. RESULTS AND CONCLUSION: Vertebral body under different loading conditions had obvious differences in axial displacement and deflection angle. Root mean square error analysis showed that compared with the other two methods, data obtained by grey value assignment method were more close to the real experimental data. It did not produce obvious stress step phenomenon in material assignment junction, and could not produce obvious stress concentration phenomenon, was more in line with the mechanical properties of vertebral body. Thus, more accurate statics analysis of the spine can be carried out. [ABSTRACT FROM AUTHOR]

BACKGROUND: Paravertebral muscles play an important role in maintaining spinal balance. The finite element model of skeletal muscle is more close to the biomechanical environment of human body. However, the muscle modeling in the finite element analysis of the spine is more complex or the muscle force is simplified in the current finite element analysis of the spine. OBJECTIVE: To quickly establish the paravertebral muscle model and analyze loading of muscle force. METHODS: Based on the principle of reverse engineering, the three-dimensional reconstruction of the spine model was carried out through CT image data. The spring stiffness of the longest lumbar muscle and ligament in the erector spinalis muscle was calculated through the elastic modulus, muscle crosssectional area and average length of muscle line. The muscle modeling was carried out through the upper and lower attachment points, and the biomechanical verification of the established finite element model was carried out. The lumbar spine was simulated by applying a bending moment of 4 N•m for flexion and extension, left and right lateral bending, left and right rotation. RESULTS AND CONCLUSION: (1) Biomechanical verification showed that L4-L5 showed elastic properties under axial load. (2) Through the analysis of lumbar flexion and extension, left-right lateral bending and left-right rotation, a finite element model of skeletal muscle was established, which was consistent with the range of motion of lumbar spine. (3) The finite element model of lumbar spine with muscle tissue conforms to the biomechanical characteristics of human body, which provides a reference for analyzing the changes of the spine under orthopedic force. [ABSTRACT FROM AUTHOR]

A dragonfly can hover, flap its wings for flight and fly vertically for a short distance. The membranous wings of a dragonfly have a high load-bearing capacity for static and dynamic load during flight. The mass of the wings of a dragonfly is only 1%-2% of its whole body but the wings can stabilize its body. The statics properties of biomimetic models were researched. The finite element software ANSYS was used to simulate the dragonfly wing. The veins were simulated by pipe20 with two nodes and the membranes by shell43 with four nodes. The influence of geometrical nonlinearity was taken into account but material nonlinearity. The models were assumed in the elastic range. The three-dimensional model of the dragonfly wing was reconstructed using reverse engineering software Imageware. The veins of dragonfly wing were drawn with AutoCAD and the membranes were added with ANSYS. The finite element models imitating the dragonfly wing were established by using free meshing. The finite element models of the dragonfly wing were simulated with structural statics. The deformation, the stress and the strain of the models under loads were analyzed respectively. The loads include the uniform load, the bending moment and the torque. Under the uniform load, the deformation of the finite element model imitating a dragonfly wing is very small, and increases gradually from the base to the wing tip. The base of the model bears heavy stress, the middle parts smaller, and the wing tip the least. The strain shows a radial pattern along the longitudinal veins, and reduces gradually from the base to the wing tip of the model. Under the bending moment, the deformation and the rotation angle around y axis increase gradually from the base to the wing tip of the model. The heavy stress and strain are mainly concentrated on the base of the model. The small stress and strain are acted on the middle parts and the wing tip. The distribution trend of the stress and strain is in substantial agreement. Under the torque, the finite element model imitating a dragonfly wing deforms only a little as a whole. The heavy deformation is mainly concentrated on the leading edges and the rear edges of the model. The smaller deformation is acted on the middle parts and the least deformation on the base. The maximum stress and strain occur at the middle parts of the model. The minimum stress and strain occur at the base of the model. The dragonfly wing is a two-dimensional truss structure with excellent rigidity. The dragonfly wing deforms only a little under loads. It is shown that the grid structures of the dragonfly wing deforming together at the boundaries of veins and membranes have excellent integrity. The understanding of dragonfly wings' characteristics provides some reference for improving the properties of two-dimensional composite materials through biomimetic designs. [ABSTRACT FROM AUTHOR]

This paper reports an experimental study about the mechanical properties of square rigid flange used in steel transmission poles. Static tests were carried out on six specimens of square flange in two groups, and finite element models were employed to simulate the test loading procedure. It is indicated that good agreement exists between FEA results and experimental results. According to the current standards, the square flange and ribs can be safely designed with the method of circular flange design, but it is unreliable to use the method for bolts under combined tension and bending stresses. Actually, overstress of bolts is caused by the asymmetrical distribution of flange stiffness. In this paper, it is recommended to use the comer cut flange and ribs placed along the upper and lower sides to reduce the non-uniformly distributed stress. Finally, the axis of bolts in second row is suggested to be the rotation axis under the bending load, and the maximum stress of bolts is close to the experimental results, which is 20% larger than the value according to the current standards. [ABSTRACT FROM AUTHOR]

A total of eight simply supported bending members with two types of complicated sections including channels with complex edge stiffeners and web holes (B1-section), channels with complex edge stiffeners and ∑ type web stiffeners and web holes (B2-section) were tested, for studying the effect of web holes on different sections flexural members. The specimens included four pure bending members and four non-pure bending members. The experimental results show that all the bending strength of B2-section specimens are higher than those of B1-section and shear deformation can be obviously observed in both B1-section and B2-section specimens. Furthermore, compared with B1-section specimens, the influence of web holes is reduced because of the setting of web stiffeners for B2-section. On the same condition, compared with the specimens without holes, the failure modes of specimens with web boles do not change, but the failure position always appears on the cross section of holes. The bending strength of specimens with boles is lower, especially the B2-section specimens. The finite element analysis (FEA) results show good agreement with test results in terms of bending strength and buckling mode. The stress distribution of the beams with web holes were compared with beams without web holes under the same condition by FEA. It is shown that the web holes change the stress distribution of the specimens. The positions of the maximum stress of BI-section and B2-section specimens are near the holes and on the compression flange near loading points respectively. [ABSTRACT FROM AUTHOR]

The inverse hanging method is a form generation method for zero bending moment space structures, which is based on the mechanical balance principle, and has played an important role at the beginning of the structural morphology research. However, with the restrictions of the law of similitude, test precision and other factors, this method has rarely been used in practical engineering directly. To solve these problems, a numerical inverse hanging method on the basis of nonlinear finite element technique is presented. This method used flexible cable and membrane element to simulate the inversed structure, and with introducing variable elastic modulus technology and combining with the basic idea of bisection method. It discussed the accuracy control of the inversed structure's shape. And then, the accuracy of the numerical method was verified by observing an experiment model and comparing its shape with the numerical simulating results. On this basis, with discussing the influence of all kinds of constraints on the structural form, it solves the problem of form diversification for the inversed structures. This paper created some numerical forms for several project instances by using the method proposed in this paper to show that it is feasible in practice. [ABSTRACT FROM AUTHOR]