Strength Calculation Analysis of Diesel Engine Linkage Based on Three-Dimensional Contact Finite Element Method

This paper presents the stress analysis of the maxillary second premolar tooth under thermal loading as a result of hot/cold liquid in the mouth using the three-dimensional (3D) finite element method (FEM). The tooth was considered to be in a restored state with composite resin and amalgam on glass-ionomer as the base material. In the first step of the study, the temperature changes as a result of hot/cold liquid in the mouth were calculated. The thermal stress distributions owing to the temperature changes were then obtained. All calculation programs were prepared by the authors using FORTRAN 77. The tooth was assumed to be isotropic, homogeneous, elastic and unsymmetric. The distribution of temperature and stress were plotted for some critical points.

In recent years, the use of castellated beams has increased significantly across all types of structures. The castellated beam is one of several methods for reducing the weight and cost of steel in construction. In this study, the static and dynamic behavior of castellated beams is investigated via the three-dimensional finite element method. The primary objective of this study is to investigate in detail the effect of web opening shapes on displacement, stress values, and free vibration of castellated beams. The investigation is done using ANSYS 22 R1. In the analysis, 4 different web opening types circle, square, pentagon, and hexagon are used. To generate the models via the finite element method a 10-node tetrahedral type finite element is implemented. This study will employ a linear isotropic homogeneous material with the mechanical properties of steel. As boundary conditions, fixed – fixed, fixed – pinned, and fixed – free are considered. The results for circular, square, pentagon, and hexagon castellated beams made from IPE120, IPE180 and IPE240 profiles are presented in detail. Based on the results, it is seen that the type of web opening has a significant effect on the displacements, von-Mises stresses, maximum shear stress and free vibration values of the considered structures.

Three-dimensional finite element analysis for stress in the periodontal tissue by orthodontic forces

The aim of this study was to investigate the biomechanical mechanisms of treatment of thoracolumbar compression fracture with pedicle screws at injury level based on a three-dimensional finite element method. We constructed one three-dimensional finite element model of T11-L1 in a patient with a compression fracture of the T12 vertebral body(anterior edges of vertebral body were compressed to 1/2, and kyphosis Cobb angle was 18.6°) fixed by four pedicle screws and another model fixed by six pedicle screws at the injured vertebrae, and then assigned different forces to the two models to account for axial compression, flexion, extension, left lateral bending, and rightward axial rotation by Ansys software. After different loading forces were applied to the models, we recorded stress measurements on the vertebral pedicle screws, as well as the maximum displacement of T11. The stress distribution suggested that stress concentration was appreciable at the root of the pedicle screws under different loading modalities. Under axial compression, flexion, extension, left lateral bending, and rightward axial rotation load, the stress for the superior screw was significantly greater than the stress for the inferior screw (P < 0.05). The stress in the six pedicle screw fixation model was significantly decreased compared to the four screw interbody fusion model (P < 0.05), but the maximum displacement of T11 between two models under different loadings was not statistically different. The use of pedicle screws at injured vertebral bodies may optimize internal fixation load and reduce the incidence of broken screws.

Three-dimensional finite element analysis should be used in stability analysis of slope because it can overcome the short advantages of two-dimensional finite element and can simulate the complex topographic and geological conditions. Based on the large-scale triaxial shear test, the modified Duncan-Chang model is established. Based on strength reduction elasto-plastic finite element, stability of high fill embankment was studied with three-dimensional finite element method considering the complex terrain conditions. Study results suggest that plastic strain and displacement mutant of slip surface node can be a sign of slope instability as a whole. At the same time calculation of three-dimensional finite element also does not converge. Therefore, it can be slope instability criterion calculate whether the finite element static analysis converges or not. On the other hand, stability safety factor of high fill embankment under three-dimensional conditions is larger than that of two-dimensional conditions, which shows that boundary conditions of high fill embankment enhance its stability.

There are many different types of orthognathic surgery, such as sagittal split ramus osteotomy, for jaw deformities. Several surgeries are combined for difficult cases, such as simultaneous movement of the upper and lower jaws. In recent years, use of the TAD and various methods of corticotomy have been considered as adjunctive surgical treatments in orthodontics for reduction of treatment time, simplification of the surgical procedures, and mitigation of surgical invasion. Orthodontic indications for the temporary screw type anchorage device became more common with the introduction of coverage under the Japanese Social Insurance System for new medical technology in April 2014. This allows the use of the temporary screw type anchorage device for preoperative orthodontic treatment, opening the possibility for its more frequent application in the future. We constructed a three-dimensional model of the maxilla to evaluate the utility of the temporary screw type anchorage device for preoperative orthodontic treatment, and to investigate stress changes affecting the alveolar bone after extraction of first premolars using the three-dimensional finite element method. Effect of tractive force using a temporary screw type anchorage device in alveolar bone -Stress analysis using the three-dimensional finite element method-

Objective To assess stresses produced by different obturator prostheses. Methods Three-dimensional finite element models of unilateral maxillary defects rehabilitated with different obturators were constructed. The different stresses were analyzed by three-dimensional finite element method under different load angle. Results The Von Mises stress values obtained for the remaining tissues adjacent to defect cavity were higher when rehabilitated by inferior hollow obturator in comparison with by superior hollow obturator. The maximum of Von Mises were higher when rehabilitated by resilient hollow obturator than by rigid hollow obturator. It was also observed that in the rigid type stress distribution contours formed in the remaining tissues adjacent to defect cavity, while in resilient hollow obturator prostheses the stress distributed mainly in the prosthesis itself. The oblique load shows the most maximum of Von Mises among all types of obturator prostheses. Conclusions A high lateral wall of an obturator may be more better in preserving the remaining structures than a shorter prosthesis lateral wall. A soft liner may be incorporated to reduce the pain of the residual maxillary structures and mucosa. When load on defect, higher stress would be generated to the residual maxillary structures. The adjustment of occlusual relationship is very important.

Verification of a three-dimensional unstructured finite element method using analytic and manufactured solutions

During hot metal forming, the temperature variation and plastic deformation affect each other considerably. In the present investigation, ring rolling of hot steel is simulated by using a three-dimensional thermo-coupled rigid-viscoplastic finite element method. A new term is added to the functional in the variational approach to consider the influence of the frictional torque of the mandrel bearing, and the coupled thermal-mechanical simulation is performed by the iteration between the rigid-viscoplastic finite element analysis and the thermal finite element analysis. Since the deformation region and the severe temperature changes are restricted to the vicinity of the roll gap, only a ring segment and parts of the rolls are analyzed using a steady-state treatment to save computation time. Roll force and torque, width spread, temperature distributions, the distributions of strain and strain rate and the distributions of relative velocity and stress at the roll surfaces are obtained. The results show that the angular velocity of the driven roll has a significant influence on the temperature variations in the ring and the rolls, to which attention should be paid in the design of the process. The method presented can also be used to analyze other forming processes such as unsymmetrical plate rolling, symmetric rolling, and extrusion.

Analysis of non-steady state slab edging in roughing trains by a three-dimensional rigid-plastic finite element method

Direct drive motor-pumps have attracted a lot of attention from researchers because of high efficiency and compact structure. This paper presents a new type of direct drive motor-pump, which integrates the structure of the radial piston pump and axial-flux permanent-magnet machine. The rotor of the disc motor is fixedly connected to the pump rotor, and the new pump uses a new type of distribution shaft for oil distribution. This structure reduces the intermediate transmission mechanism, and the application of the disc motor further reduces the axial size, the overall volume, and heat dissipation. The efficiency of the entire system has been improved. The three-dimensional finite element method is used to dynamically analyze flow field in the flow channel, which is extracted and simplified. The flow and pressure of the pump meet the design requirements in the simulation. A disc motor was designed for the pump, and the theoretical formula of the disc motor was derived. The initial size of the motor was obtained. The response surface method and three-dimensional finite element are used to optimize the corresponding axial-flux permanent-magnet machine. Loading the torque condition of the pump to the load end of the motor, the response of the motor meets the requirements.

ObjectivesThe aim of this study was to clarify the effect of the play between the bracket and the archwire on anterior tooth movement subjected to the retraction force from various lengths of power arms in sliding mechanics.Materials and MethodsA three-dimensional finite element method was used to simulate en masse anterior tooth retraction in sliding mechanics. The displacements of the maxillary incisor and the archwire deformation were calculated when the retraction force was applied.ResultsWhen a play did not exist, bodily movement was obtained at 5.0 mm length of power arm. In case a play existed, bodily movement was observed at the power arm length of 11.0 mm.ConclusionsIn the actual clinical situation, a bracket/archwire play and the torsion of the archwire within the bracket slot should be taken into consideration to prescribe an optimal power arm length and to achieve effective anterior tooth movement.

A new method is proposed to estimate, by a three-dimensional finite element method, the distribution of tooth root stress of a gear pair under partial and nonuniform contact. In this method, the usual finite element program can be used with no special changes. To check the accuracy of the present method, a contact problem using two circular discs is analysed. Compared with the results by Hertz theory, accurate numerical results are obtained by this new method. A pair of spur gears with lead error, which results in partial contact, is also analysed by the present method, and the distribution of tooth root stress and tooth deflection are obtained. The results are compared with those given by the draft proposal of the ISO and by the standards of the AGMA.

The purpose of this study was to calculate the temperature and thermal stress distribution as a result of hot/cold liquid in the mouth. This numerical study was carried out using three-dimensional finite element models and the tooth model was crowned with Au-Pd alloy, Ni-Cr alloy and porcelain. In the first part of the study, temperature changes as a result of hot/cold liquid in the mouth were calculated. In the second part, the thermal stresses caused by temperature changes were obtained. The tooth was assumed isotropic, homogenous, elastic and unsymmetrical. The authors using fortran 77 prepared all calculation programs. The distribution of temperature and thermal stress were plotted for some critical points.

A three-dimensional finite element model of a femoral head was developed using a surface modeling technique. The distribution of the stress index S (S = effective stress / yield strength, sigma/sigmaY) in various sizes of segmental osteonecrosis was assessed. The stress index of the femoral head was within physiological limits when the necrotic angle was less than 110 degrees. Within both the subchondral region and the deep necrotic region adjacent to the necrotic-viable interface, values of the stress index significantly higher than the normal physiological level (>0.1) appeared when the necrotic angle was 110 degrees or more. In the analysis of 28 osteonecrotic femoral head specimens, fracture appeared in two major locations: the deep necrotic region near the underlying necrotic-viable interface (19 femoral heads) and the subchondral region (7 femoral heads). In 2 femoral heads, the fracture involved both regions. Both sites of fracture coincided with the region of stress index greater than 0.1 in the finite element model study. These results may provide baseline information for predicting the collapse of the femoral head and determining the treatment modality of early stage osteonecrosis.