Three-Dimensional Elastoplastic Finite-Element Analysis for Link Chains in Chain Hoist.

Link chains used in chain hoists are often subjected to combined loads of torsion, tension, dynamic and bending moments. They are usually fractured by fatigue. A few investigations have been carried out on the behavior of fatigue for link chains. In this paper, a procedure for a prediction S-N curves is examined using three dimensional elastic-plastic finite-element analysis and Coffin-Man-son's law. Fatigue tests were conducted for link chains in order to examine fatigue strength of 106 cycles. It is found that the procedure suggested in this paper is quite stuitable for the prediction of S-N curves. From the fatigue tests and the finiteelement analysis, it is found that a crack initiates from the border between the straight part and the curved part of the inner surface of a link chain. Comparison between the numerical and the experimental results is made for the strain measurement and stress distribution. The numerical results corresponds with the experimental results fairly well.

The purpose of this study was to investigate the effects of composite resin restorations on the stress distribution of notch shaped noncarious cervical lesion using three-dimensional (3D) finite element analysis (FEA). Extracted maxillary second premolar was scanned serially with Micro-CT (SkyScan1072 ; SkyScan, Aartselaar, Belgium). The 3D images were processed by 3D-DOCTOR (Able Software Co., Lexington, MA, USA). ANSYS (Swanson Analysis Systems, Inc., Houston, USA) was used to mesh and analyze 3D FE model. Notch shaped cavity was filled with hybrid or flowable resin and each restoration was simulated with adhesive layer thickness () A static load of 500 N was applied on a point load condition at buccal cusp (loading A) and palatal cusp (loading B). The principal stresses in the lesion apex (internal line angle of cavity) and middle vertical wall were analyzed using ANSYS. The results were as follows 1. Under loading A, compressive stress is created in the unrestored and restored cavity. Under loading B, tensile stress is created. And the peak stress concentration is seen at near mesial corner of the cavity under each load condition. 2. Compared to the unrestored cavity, the principal stresses at the cemeto-enamel junction (CEJ) and internal line angle of the cavity were more reduced in the restored cavity on both load con ditions. 3. In teeth restored with hybrid composite, the principal stresses at the CEJ and internal line angle of the cavity were more reduced than flowable resin.

The link chains, which are used in lifting machines such as a chain hoist and a conveyor, are very important components in those machines because the fatal accident may occur by the falling of a load when a link chain is fractured. They are usually fractured by fatigue. Therefore the fatigue of the link chain becomes large problem in loading facilities. However, not only fatigue characteristics but also stress distributions have not been clear due to the complex shape of a link chain. In this paper, in order to clarify fatigue characteristics of link chain, the stress distribution in a link chain was analyzed by the finite element analysis (FEM) and the result was compared with the measurement values by strain gauges. In addition, fatigue tests of link chains were carried out in order to evaluate the fatigue strength, and then the fatigue fracture surfaces were observed by the scanning electron microscope (SEM).

Comparison of the biomechanical behavior of different fixation configurations following Le Fort I advancement and inferior repositioning surgery: A three-dimensional finite element analysis.

Comparison of five different fixation techniques of sagittal split ramus osteotomy using three-dimensional finite elements analysis

Residual thermal strains and stresses in nickel aluminide matrix composites

Three-dimensional finite element analysis of cold expansion of adjacent holes

Full-scale field tests were conducted on two 8.5-m (28-ft) span reinforced concrete arch culverts. The culverts were subjected to service live loads at depths of cover from 0.3 to 0.9 m (1 to 3 ft). At 1 ft of fill, the culverts were loaded with a simulated single-axle live load greater than 980 kN (220,000 lb). Field data collected included arch deflection, interface pressure, concrete strain, and reinforcing strain. The computer modeling of the live-load tests is reported. Two- and three-dimensional finiteelement analyses were conducted. Nonlinear material models were used for the backfill soil and the reinforced concrete in both the two- and three-dimensional analyses. Results from the finite-element analyses are compared with the field test data. Results of this study indicate that the two-dimensional models are limited in their ability to predict the longitudinal spreading of live load forces in the culverts and to predict maximum moments larger than those in the actual structure. The three-dimensional finite-element deflection predictions were dependent on the properties used to define the concrete material model; however, the design forces (moment, thrust, and shear) did not show the same sensitivity. This indicates that for typical structural design, material parameters may be approximated without seriously degrading the accuracy of predicted design forces. The test structures met AASHTO design criteria for strength and serviceability.

Objective To evaluate the effects of femoral offset (FO) on the stress level of bone cement total hip arthroplasty (THA) in the elder patients by the three-dimensional finite element analysis. Methods The normal bilateral hip joints in two cases was determined with CT imaging,with parameters including FO,neck shaft angle and neck length.The three-dimensional finite element model of THA was built so as to make Von Mises stress analysis of the changes of different neck lengths,neck shaft angles and FO. Results Stress levels in the prosthesis and bone cement reduced monotonically with the increase of neck shaft angles.In the meantime,the stress levels were lowered when neck length was in a range of 35-44 mm,but beyond the range they showed monotonous increase. Conclusions The reduction of stress levels of prosthesis and bone cement,promotion of femur stress and extension of range of motion of hip joints are closely related to FO.FO reconstruction benefits the restoration of abductor force arm and biomechanical function of normal hip joints. Key words: Femur; Arthroplasty,replacement,hip; Finite element analysis; Offset

Purpose To investigate effects of number and location on patterns of von Mises stress distribution and volume average stress on abutment tooth, edentulous ridge, mini dental implant, and surrounding bone of mini dental implant-assisted mandibular Kennedy class I removable partial denture. Materials and Methods Eight three-dimensional finite element models of mandibular Kennedy class I with different numbers and locations of mini dental implants were constructed. Mini dental implants were generated in the area of second premolar, first molar, and second molar, respectively. A static load of 400 N was applied on all models. The von Mises stress and volumetric average stress were calculated by three-dimensional finite element analysis. Result The minimum volumetric average stress of abutment tooth was found in the model, where there was one mini dental implant at the second molar position and 2 mini dental implants at first molar and second molar positions. The model with three mini dental implants had reduced volumetric average stress of abutment tooth, which was not different from the model with two mini dental implants. However, the minimum volumetric average stress of mini dental implant and surrounding bone were found when three mini dental implants were applied, followed by two and one mini dental implants, respectively. Conclusion Placing at least one mini dental implant at a second molar position can help reduce stress transferred to the abutment tooth. Stresses around each implant and surrounding bone reduced with increased numbers of mini dental implants.

Clarification of the protocol for using short implants is required to enable widespread use of short implants as an available treatment option. The purpose of this study was to investigate the influences of implant length and diameter, bicortical anchorage, and sinus augmentation on peri-implant cortical bone stress by three-dimensional finite element analysis. For bone models with bone quantity A and C in the maxillary molar region, three-dimensional finite element analysis was performed using different lengths and diameters of implant computer-aided design models, and the degree of maximum principal stress distribution for each model was calculated. For bone quantity A models, the degree of stress distribution of the 4-mm-diameter, 6-mm-length implant was the greatest. For bone quantity C models, the degree of stress distribution of the 5-mm-diameter, 6-mm-length implant with bicortical anchorage was much smaller than that for the 4-mm-diameter, 13-mm-length implant with sinus augmentation. The results of this study suggest that 6-mm-length implants should be selected in cases with bone quantity C where the bone width permits increasing implant diameter from 4 mm to 5 mm.

To investigate the clinical application effect of the along-axis extraction method in the extraction of impacted mandibular third molars (IMTM) and to compare the biomechanical characteristics of different root extraction techniques through three-dimensional finite element analysis. A total of 68 patients requiring IMTM extraction were enrolled and randomly divided into two groups: the experimental group underwent the along-axis extraction method, while the control group underwent the traditional buccal bone removal and root extraction method. The duration of the procedure, intraoperative and postoperative complications were recorded. Three-dimensional finite element analysis further revealed the stress distribution in the tooth root, jawbone, periodontal ligament, and mandibular canal during different root extraction methods. The duration of root extraction, pain score and swelling on the first postoperative day in the control group were (7.87±3.90) min, 4.62±1.90 and (11.37±5.12) mm, respectively, which were significantly higher than those in the experimental group [(5.74±2.37) min, 3.87±1.19 and (7.22±3.39) mm, respectively]. The root fracture rate and lingual bone plate fracture rate in the control group were significantly higher than those in the experimental group (P < 0.05). The results of finite element analysis showed that the control group ' s lingual al-veolar bone had the higher peak equivalent stress, and lingual bone plate fracture was prone to occur. The periodontal ligament of the experimental group had the higher equivalent stress value, making it more likely to rip and more likely to cause root displacement. When subjected to force, the experimental group' s instantaneous root displacement was higher, but the control group ' s root displacement was more pronounced in the lingual direction. This study suggests that the along-axis extraction me-thod can not only effectively shorten the operative time but also reduce postoperative complications after extraction of impacted mandibular third molars, and enhance the safety of the operation and the patient' s comfort. Three-dimensional finite element analysis shows the biomechanical characteristics of various root extraction techniques visually, serves as a valuable guide for choosing and refining clinical surgical techniques, and confirms that extracting a tooth' s root along its long axis yields better clinical results.

Design of an optical fibre sensor patch for longitudinal strain measurement in structures

The stress of band adhesive butt joints, in which two adherends were bonded partially at the interfaces, were analyzed, using a two-dimensional theory of elasticity, in order to demonstrate the usefulness of the joints. In the analysis, similar adherends and adhesive bonds, which were bonded at two or three regions, were respectively replaced by finite strips. In the numerical calculations, the effects of the ratio of Young’s modulus for adherends to that for adhesives, the adhesive thickness, the bonding area and position, and the load distribution were shown on the stress distribution at the interface. It was seen that band adhesive joints were effective when the bonding area and positions were changed with external load distributions. Photoelastic experiments and experiments concerning the strains of adherends were conducted. The analytical results were in a fairly good agreement with the experimental results. In addition, a method for estimating joint strength is proposed by using the stress distribution at the interface obtained by the analysis. Experiments concerning the joint strength were performed. Fairly good agreement was found between the estimated values and the experimental results.

This report summarizes efforts to develop elastic and elastic-plastic fracture mechanics analyses for internal surface cracks in elbows. The analyses involved development of a GE/EPRI type J-estimation scheme which requires an elastic and fully plastic contribution to crack-driving force in terms of the J-integral parameter. The elastic analyses require the development of F-function values to relate the J{sub e} term to applied loads. Similarly, the fully plastic analyses require the development of h-functions to relate the J{sub p} term to the applied loads. The F- and h-functions were determined from a matrix of finite element analyses. To minimize the cost of the analyses, three-dimensional ABAQUS finite element analyses were compared to a simpler finite element technique called the line-spring method. The line-spring method provides a significant computational savings over the full three-dimensional analysis. The comparison showed excellent agreement between the line-spring and three-dimensional analysis. This experience was consistent with comparisons with circumferential surface-crack analyses in straight pipes during the NRC`s Short Cracks in Piping and Piping Welds program.