The effects of shape memory alloys’ tension–compression asymmetryon NiTi endodontic files’ fatigue life

Author(s):  
MR Karamooz-Ravari ◽  
R Dehghani

Nowadays, NiTi rotary endodontic files are of great importance due to their flexibility which enables the device to cover all the portions of curved canal of tooth. Although this class of files are flexible, intracanal separation might happen during canal preparation due to bending or torsional loadings of the file. Since fabrication and characterization of such devices is challenging, time-consuming, and expensive, it is preferable to predict this failure before fabrication using numerical models. It is demonstrated that NiTi shape memory alloy shows asymmetric material response in tension and compression which can significantly affect the lifetime of the files fabricated from. In this article, the effects of this material asymmetry on the bending response of rotary files are assessed using finite element analysis. To do so, a constitutive model which takes material asymmetry into account is used in combination with the finite element model of a RaCe file. The results show that the material asymmetry can significantly affect the maximum von Mises equivalent stress as well as the force–displacement response of the tip of this file.

Author(s):  
Bisen Lin ◽  
Richard C. Biel

In this paper, a rational stress limit based on the von Mises equivalent stress is established for pipelines subjected to internal pressure. This stress limit is based on the ASME pipeline Code’s design margin for the service and location of the installation [1, 2]. These Codes are recognized by 49 CRF192 [5]. Both capped-end and open end conditions are considered. The single value of stress limits can be derived by classical hand calculations for use in assessing the results of a finite element analysis (FEA). Two application examples are presented showing studies done with the ABAQUS [3], a commercial (FEA) software. A stress limit was first found using classical hand calculations and verified by a simple finite element model. The linearized stresses at some critical locations were then compared to the established stress limit, and multiples, for the assessments of membrane, membrane plus bending, etc. stresses. This paper is not intended to revise or replace any provision of ASME B31.8 [2]. Instead, it provides a rational stress limit that may be used in the assessment of detailed FEA analyses of pipelines and the associated components.


2014 ◽  
Vol 577 ◽  
pp. 218-221 ◽  
Author(s):  
Yan Jie Guo ◽  
Wei Wang ◽  
Qing Dong Cui ◽  
Hui Dou

The lateral longitudinal beam is one of the most important mechanical parts in secondary protection equipment of electrical power system. Basing on the simulation analysis platform of ANSYS Workbench, the standardization of the modular hole of the lateral longitudinal beam is studied in this research. The static and dynamic finite element analysis of the lateral longitudinal beam are used to obtain Von-Mises equivalent stress, deformation data, the natural frequency and vibration mode of five orders. The contrastive analysis of the results of finite element analysis provides a kind of theoretical instruction for the dimension selection of the modular hole.


1994 ◽  
Vol 116 (4) ◽  
pp. 401-407 ◽  
Author(s):  
J. Chen ◽  
Liangfeng Xu

A 2-D finite element model of the human temporomandibular joint (TMJ) has been developed to investigate the stresses and reaction forces within the joint during normal sagittal jaw closure. The mechanical parameters analyzed were maximum principal and von Mises stresses in the disk, the contact stresses on the condylar and temporal surfaces, and the condylar reactions. The model bypassed the complexity of estimating muscle forces by using measured joint motion as input. The model was evaluated by several tests. The results demonstrated that the resultant condylar reaction force was directed toward the posterior side of the eminence. The contact stresses along the condylar and temporal surfaces were not evenly distributed. Separations were found at both upper and lower boundaries. High tensile stresses were found at the upper boundaries. High tensile stresses were found at the upper boundary of the middle portion of the disk.


2021 ◽  
Author(s):  
Sinan Yıldırım ◽  
Ufuk Çoban ◽  
Mehmet Çevik

Suspension linkages are one of the fundamental structural elements in each vehicle since they connect the wheel carriers i.e. axles to the body of the vehicle. Moreover, the characteristics of suspension linkages within a suspension system can directly affect driving safety, comfort and economics. Beyond these, all these design criteria are bounded to the package space of the vehicle. In last decades, suspension linkages have been focused on in terms of design development and cost reduction. In this study, a control arm of a diesel public bus was taken into account in order to get the most cost-effective design while improving the strength within specified boundary conditions. Due to the change of the supplier, the control arm of a rigid axle was redesigned to find an economical and more durable solution. The new design was analyzed first by the finite element analysis software Ansys and the finite element model of the control arm was validated by physical tensile tests. The outputs of the study demonstrate that the new design geometry reduces the maximum Von Mises stress 15% while being within the elastic region of the material in use and having found an economical solution in terms of supplier’s criteria.


2014 ◽  
Vol 607 ◽  
pp. 713-716
Author(s):  
Wen Liang Tang ◽  
Chun Yue Huang ◽  
Tian Ming Li ◽  
Ying Liang ◽  
Guo Ji Xiong ◽  
...  

In this paper, ANSYS-LSDYNA simulation software is used to build the three-dimensional finite element model of the ball bond and to get the Von Mises stress. The change of stress about the bump is researched which base on the model in different bonding pressure, bonding power and bonding time. The result show that: The stress increase with bonding pressure increase within a certain bonding pressure range, and then the stress will maintain a table number, however, the stress will continue to increase when the bonding pressure reach a certain value; increasing the bonding power, the area of lager stress will grow; prolonging the bonding time, the stress of the pad will increase with time, but when time increase to a certain value, the stress of the pad will not increase over time.


2014 ◽  
Vol 680 ◽  
pp. 249-253
Author(s):  
Zhang Qi Wang ◽  
Jun Li ◽  
Wen Gang Yang ◽  
Yong Feng Cheng

Strain clamp is an important connection device in guy tower. If the quality of the compression splicing position is unsatisfied, strain clamp tends to be damaged which may lead to the final collapse of a guy tower as well as huge economic lost. In this paper, stress distribution on the compressible tube and guy cable is analyzed by FEM, and a large equivalent stress of guy cable is applied to the compression splicing position. During this process, a finite element model of strain clamp is established for guy cables at compression splicing position, problems of elastic-plastic and contracting are studied and the whole compressing process of compressible position is simulated. The guy cable cracks easily at the position of compressible tube’s port, the inner part of the compressible tube has a larger equivalent stress than outside.


2014 ◽  
Vol 529 ◽  
pp. 92-96 ◽  
Author(s):  
Song Yi Guo ◽  
Chong Li ◽  
Wen Yi Li

Flywheel rotor is the very important component in the flywheel energy storage system (FESS). The key factors of rotor, such as rotor materials, geometry and fabrication process, have directly influence on the performance of FESS. At present, press-assembling the rotor with shrink-fit is used usually to increase strength of composite flywheel rotors filament wound in the radial direction. This paper is concerned that the Von Mises equivalent stress distribution of the metal hub and the radial stress distribution of the composite rim at the speed of 20000rpm by the 3D finite element method. The materials and corresponding minimum value of interference fit of the flywheel rotor are determined based on the analysis results.


2014 ◽  
Vol 548-549 ◽  
pp. 449-453 ◽  
Author(s):  
Zhi Qiang Guo ◽  
Ze Lu Xu

For the problem of balance bearing of universal spindle in rolling mill being prone to damage, the paper established mechanical model and finite element model of universal spindle. The paper has analyzed that the shear and bending moment in the middle of the shaft is the largest. The fillet near shoulder of balance bearing of the spindle is dangerous part. In order to reduce principal stress of universal spindle caused by moment, the paper improved balance mode of the spindle. The equilibrant was applied from in one place of shaft to put in two places. After optimizing, equivalent stress of the spindle is slight smaller than before under the same loading condition, which illustrates that the strength of the spindle is appropriately improved. Although the effect is not obvious, this has played a guiding role for the optimization of balance mode of universal spindle.


2014 ◽  
Vol 945-949 ◽  
pp. 190-193
Author(s):  
Hai Lin Wang ◽  
Yi Hua Sun ◽  
Ming Bo Li ◽  
Gao Lin ◽  
Yun Qi Feng ◽  
...  

Q43Y-85D type crocodile hydraulic clipping machine was taken as research object to optimization design. A finite element model for clipping machine was built using shell unit as fundamental unit. ANSYS12.0 finite element method was used to analyze the deformation and stress distribution of the shear platform model of hydraulic clipping machine. The result showed that the maximum equivalent stress at the dangerous area was 368.162 MPa and the maximum elastic strain was 0.1814×10-2 mm. After the structural optimization design, it was found that the maximum equivalent stress decreased to 186.238 MPa which did not exceed the material’s yield limitation 215 MPa and the maximum elastic strain decreased to 0.919×10-3 mm which satisfied the requirement of stiffness.


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