Experimental Stress Analysis on Frame Structure of A 70-Passengers Electric Bus

Evaluation of sensor-enabled piezoelectric geoelectric cable in cyclic shear tests of subgrade soil under vertical cyclic loads

<p>The bolster is one of the main structural elements in railway bogies, playing the central role of transmitting vertical and dynamic loads from the train body to the wheel-sets. The mechanical behavior of an ASTM A148 Grade 80-50 material bolster under vertical static loading is examined in this work. This simulation is analyzed by applying the Finite Element Analysis (FEA) using student version software with nonlinear static analysis, which was run with a tetrahedral mesh and Newton-Raphson iteration. There are three variables, respectively, two variables as dependent, such as Von Misses Stress (VMS) and total deformation resulting from the loading condition. Then, the independent variable is a loading value based on the AAR M-202 standard. In this work, three values of loading condition were carried out, such as P1 = 536010.7 N, P2 = 854058.8 N, P3 = 1027500 N respectively. The result of the simulation shows that the maximum average stress in the critical area is 305.58 MPa, which is still less than the yield strength of the material at 390 MPa. The maximum elastic deflection of 0.102 mm is well within the AAR M-202 standard allowable values. In conclusion, bolster bogie based on ASTM A148 Grade 80-50 has reliability for static loading and is available with a safety factor according to the AAR M-202 standard.</p>

BackgroundSplinting is commonly employed to stabilize periodontally compromised teeth, but the choice of splint material significantly influences stress distribution within the periodontal ligament (PDL) and surrounding bone. This study aimed to evaluate and compare the stress distribution of four different splint materials—composite, fiber-reinforced composite (FRC), polyetheretherketone (PEEK), and metal—on mandibular anterior teeth with 55 % bone loss using finite element analysis (FEA).MethodologyFinite element models of mandibular anterior teeth with 55 % bone loss were developed using SOLIDWORKS 2020. Simulations were conducted for non-splinted teeth and for teeth splinted with composite, FRC, PEEK, and metal. Stress analysis was performed in ANSYS software under vertical (100N at 0°) and oblique (100N at 45°) loading conditions. Von Mises stress values in the PDL and cortical bone were recorded and statistically analyzed using MedCalc software to compare the performance of different splint materials.ResultsNon-splinted teeth exhibited the highest stress levels, particularly under oblique loading conditions. Among the splinting materials, FRC showed the most effective reduction in stress across all teeth, especially under vertical loads. Composite and metal wire splints provided moderate stress reduction, with performance varying depending on the load angle. PEEK splints demonstrated good stress reduction under vertical loads but showed increased stress levels under oblique forces. These results underscore the influence of splint material and load direction on stress distribution in periodontally compromised teeth.ConclusionThe study highlights the critical role of splint material in reducing stress on the PDL of periodontally compromised teeth. FRC splints emerged as the most effective material for minimizing stress under both vertical and oblique loading conditions. Composite and metal wire splints offered moderate efficacy, while PEEK splints were less effective under oblique loads. These findings provide valuable insights for clinicians in selecting optimal splint materials for periodontal stabilization.

Arched Corrugated Steel Roof (ACSR) is a kind of thin-walled steel shell, composing of arched panels with transverse small corrugations. Four full-scale W666 ACSR samples with 18m and 30m span were tested under full and half span static vertical uniform loads. Displacement, bearing capacities and failure modes of the four samples were measured. The web and bottom flange in ACSR with transverse small corrugations are simplified to anisotropic curved plates, and the equivalent tensile modulus, shear modulus and Poisson\'s ratio of 18m span ACSR were measured. Two 18 m-span W666 ACSR samples were analyzed with the Finite Element Analysis program ABAQUS. Base on the tests, the limit bearing capacity of ACSR is low, and for half span loading, it is 74-75% compared with the full span loading. When the testing load approached to the limit value, the bottom flange at the sample\'s bulge place locally buckled first, and then the whole arched roof collapsed suddenly. If the vertical loads apply along the full span, the deformation shape is symmetric, but the overall failure mode is asymmetric. For half span vertical loading, the deformation shape and the overall failure mode of the structure are asymmetric. The ACSR displacement under the vertical loads is large and the structural stiffness is low. There is a little difference between the FEM analysis results and testing data, showing the simplify method of small corrugations in ACSR and the building techniques of FEM models are rational and useful.

To clarify behavior and sliding resistance of a spread foundation under combined load, static vertical loading test, and static vertical and lateral combined loading tests were conducted on a spread foundation on sand. The sliding resistance under the combined load was caused by the soil failure beneath the foundation. After the peak of the lateral resistance, settlement and horizontal displacement increased although vertical and lateral load did not increase. When the vertical load is less than about 1/2 of the ultimate bearing capacity, the vertical load could be retained and the horizontal displacement was greater than the settlement.

A three-dimensional finite element analysis study on the impact of different prosthetic designs and materials for short-crowned molars with distal subgingival defects.

Single implant retained mandibular overdenture treatment has been shown to be a minimally invasive, satisfactory, and cost-effective option for edentulous individuals. However, the impact of implant diameter and length on stress distribution at the implant, bone, and other components in this treatment approach remains unclear. The purpose of this 3D finite element analysis was to evaluate the effect of implant length and diameter on equivalent von Mises stress and strain distribution in single implant retained overdentures at bone, implant, and prosthetic components. Nine models were constructed according to implant lengths (L) (8, 10, 12mm) and diameters (D) (3.3, 4.1, 4.8mm). The implants were positioned axially, in the midline of the mandible. A 3D model of the edentulous mandible was created from a computed tomography image. A single implant, abutment with insert PEEK and a housing, acrylic denture, and Co-Cr framework were modeled separately. In the ANSYS software program, occlusal loads were applied as 150 N, bilaterally vertical direction, or unilaterally oblique direction to the first molar. Minimum principal stress values were evaluated for bone and equivalent von Mises stress and strain values were evaluated for implant and prosthetic components. Von Mises stress values for vertical load increased at implant, housing, and insert PEEK for all groups when the length of the implant increased. When oblique load was applied, 3.3mm diameter implant groups showed maximum von Mises stress values for implants, cortical bone, cancellous bone, and housing among all groups. A minimum stress level for implant was found in D4.1/L8 group. Regarding the insert PEEK, strain values were found to be higher as the diameter of the implant increased both for vertical and oblique loads. Cortical bone showed higher minimum principal stress values as compared to cancellous bone under both loading conditions. The 3.3mm diameter implant groups exhibited the highest von Mises stress and strain values for both loading conditions at the implant. The diameter of the implant had a greater impact on stress and strain levels at the implant site compared to length. For vertical loading, stress value increased at implant, housing, and PEEK when the length of the implant increased.

The aim of this study was to investigate microstrains around two non-parallel implant-supported prostheses and different abutment connections and positions under vertical static load using strain gauges. 4 models simulating the mandibular unilateral free-end were fabricated. 8 implants (4.0 × 10 mm and 5.0 × 10 mm) were inserted in the second premolar, perpendicular to the occlusal plane, and the second molar, tilted at 15°. Four groups were analyzed: engaging and angled abutments (control group), both non-engaging abutments, both screw-and cement-retained prosthesis (SCRP) abutments, and engaging and non-engaging abutments. Strain gauges were placed buccally, lingually, mesially, and distally adjacent to each implant. The restoration was cement-retained in the control group and screw and cement-retained in the rest. Zirconia bridges were fixed on the abutment with NX3, and a 300 N vertical static load was applied. Microstrains were recorded and analyzed. Both non-engaging abutments showed the highest compressive microstrains (-52.975), followed by engaging, angled abutment (-25.239). SCRP-SCRP abutments had the lowest compressive microstrains (-14.505), while the engaging, non-engaging abutments showed tensile microstrains (0.418). Microstrains in SCRP-SCRP and engaging, non-engaging groups were significantly lower than in the control group (α = .05). Premolar areas showed compressive microstrains (-47.06), while molar sites had tensile microstrains (+0.91), with microstrains in premolars being significantly higher than in molar area (α = .05). The types of abutment connections and positions may have a potential effect on microstrains at the implant-bone interface. SCRP-SCRP abutments could be an alternative to use in non-parallel implant-supported prostheses when two implants make an angle of no more than 20 degrees.

Vehicles commonly encounter uneven road conditions, which can lead to torsional deformation of the frame structure. The results of finite element analysis (FEA) indicate that the highest stress occurs under torsion loading conditions. To validate these simulation results, an experimental study was conducted involving static load testing under torsional loading conditions on a hybrid frame structure, composed of SS 400 carbon steel and 6061 aluminum alloy, designed for a 70-passenger electric bus. The test was performed by applying a static load of 6,825 kg as sandbags on the seating area and aisle, and supporting the frame on three wheels only. Strain measurements were recorded using 28 strain gauges: 20 on the SS 400 carbon steel underframe and 8 on the 6061 aluminum alloy structure of the side and roof frames. The total load was the weight of 70 passengers plus a 30% dynamic load factor. Experimental analysis revealed a maximum stress value of 76.42 MPa in the SS 400 carbon steel of the underframe at location 9 in the central section of the underframe. In the 6061 aluminum alloy structure, the maximum stress value of 15.56 MPa was obtained in the roof frame directly below the air conditioner unit. Overall, the measured stress values were within the elastic ranges of the materials used, demonstrating structural integrity under load. The average difference between the experimental results for stress and the finite element analysis (FEA) simulation was approximately 11.21%.

Stress analysis of endodontically treated teeth restored with post-retained crowns: A finite element analysis study

Biomechanical evaluation of anterior lumbar interbody fusion with various fixation options: Finite element analysis of static and vibration conditions

The paper presents the results of road and simulation tests depicting the impact of vertical static load on the coupling on the braking distance of a combination vehicle. A hypothesis was put forward that verification by the vehicle user and a possible change in the static vertical load on the coupling (as a result of the incorrect position of the trailer’s centre of gravity) could influence the braking distance of a combination vehicle. The article presents the geometric and mass data obtained for the vehicles tested. This is followed by a description of road tests carried out under real conditions and the results of simulation calculations, where the braking distance of a vehicle combination consisting of a tractor unit and a loaded (in six variants) single-axle unbraked trailer was assessed. The parameters of the road surface on which the tests were carried out were defined. In the course of the tests, the distance travelled by the vehicles and the force applied to the brake pedal were recorded. The result of the work is a report presenting the results of the assessment of the braking distance depending on the static vertical load on the coupling device.

Stress distribution of different attachment systems in mandibular implant overdentures: A 3D finite element study.

진동타입기에 의해 시공되는 말뚝의 해석을 위한 해석기법을 개발하고 해석기법의 신뢰성을 평가해보기 위해 시스템변수를 달리하여 해석을 수행하였다. 말뚝의 동적 주면마찰 하중전이곡선을 결정짓는 부주면마찰력의 크기는 정적 연직하중이 작용하지 않는 경우에 대한 해석을 통해 시행착오적으로 구할 수 있을 것으로 생각된다. 진동타입기에 의해 시공되는 말뚝의 연직변위량은 정적 연직하중의 크기에 비례하는 결과를 보였다. 진동타입시 말뚝의 가속도는 부주면 마찰력 및 정적 연직하중과는 무관하며 기진력의 크기에 의존함을 알 수 있었다. 정적 연직하중의 증가에 따른 말뚝주면 하중전이곡선의 변화양상을 비교해 볼 때 진폭은 거의 일정하나 곡선이 전체적으로 상향으로 이동함을 알 수 있었다. 말뚝선단 하중전이곡선에 대하여 최대 하중값은 부주면 마찰력 및 정적 연직하중의 크기와 무관하게 일정함을 알 수 있었다. Technique for analyzing a pile installed by vibratory pile driver was developed and analyses were performed with varying system variables in order to evaluate reliability of the developed technique. Negative skin friction which defines dynamic skin load transfer curve seems to be obtained by trial and error method for the situation without static vertical load. Vertical displacment of the pile was proportional to the static vertical load. It can be seen acceleration of the pile was dependent on excitation force regardless of the negative skin friction and the static vertical load. Comparing the shapes of skin load transfer curves with static vertical load, amplitudes of the curves were nearly the same but it can be seen that the curves shift to upward. Maximum values of the toe load transfer curves were constant regardless of the negative skin friction and the static vertical load.

Influence of Implant Length and Associated Parameters Upon Biomechanical Forces in Finite Element Analyses: A Systematic Review.