Papers by Keyword: Stress Analysis

Abstract: Finite element analysis (FEA) has been proven to be a precise and applicable method for evaluating dental implant systems. This is because FEA allows for measurement of the stress distribution inside of the bone and various dental implant designs via simulation analysis during mastication where such measurements are impossible to perform in-vitro or in-vivo experiment. That is why the relationship between implant design and load distribution at the implant bone interface is a crucial issue to understand. This research study focuses on a static simulation and bonding strength for PLA/HA coating on V thread design of dental implant using three-dimensional finite element. The average masticatory muscle that involves in human biting such as X, Y and Z direction will be used to simulate force with load condition of 17.1N, 114.6N and 23.4N respectively. Based on result obtained, the coated dental implant model is more compatible than uncoated model due to lower maximum stress which is reduce about 16%. The coated model also shows lower deformation and higher bonding strength. Outcomes from this research provide a better understanding of stress distribution characteristics that would be useful in order to improve design of dental implant thread and evaluation of the PLA/HA bonding strength applied.

Abstract: Shallow cracks are often observed in dental enamel, however do not normally lead to deep fractures. Previous work has highlighted the toughening mechanisms that operate in enamel during crack propagation, but very little is known about the deformation and stress fields arising around the propagating cracks during realistic loading conditions. This work aims to elucidate how the stresses are distributed within human dental enamel when a pre-existing crack is subjected to opening and surface contact with in situ indentation. We present a synchrotron-based in situ analysis coupled with a linear elastic finite element method simulation. The experimental reconstructed stress fields identified a prominent residual stress within the enamel, accompanied by a visible pattern that appeared clearly associated with its underlying microstructure. The numerical modelling of the stress field and discerning of surface contact and crack opening caused by the indentation was subsequently possible, even if in this study the influence of the anisotropy induced by the presence of features at a smaller scale was neglected. The implications of these findings and directions for future research are discussed.

Abstract: In this study, the assessment and calculation methods for the crack propagation life of steam turbine rotor shafts containing defects are presented. The analytic methods for estimating the average stress and the alternating stress amplitude of the steam turbine rotor shafts are introduced. The defects on/in the rotor shafts were regularized by the method of fracture mechanics, and the high cycle fatigue crack propagation life and low cycle fatigue crack propagation life of the rotor shafts are estimated from Paris formula. Taking the 60MW turbine rotor shafts containing an initial surface defect and an initial internal defect as the examples respectively, the crack propagation life of them were calculated. The results indicated that the assessment method for the crack propagation life can preliminarily be both used to estimate the safety-operating life and to analyze the fracture reason of a steam turbine rotor shaft containing defects. This paper can provide reference for periodic maintenance and safety evaluation of turbine rotor shafts.

Abstract: Proppant is a key material used to support underground fractures in oil and gas reservoir stimulation. At present, the density of most proppant is so large that the settle velocity is fast, which lead to the poor transportability in the fracturing process. The ideal proppant should have a lower density, such as hollow proppant. The hollow structure reduces the proppant density, improving the proppant transportability, but affects the proppant other performances such as strength and hardness. In order to improve the problem, it is necessary to optimize the hollow structure. This paper briefly introduces the hollow proppant, and uses the finite element method to analyze the stress characteristics of proppant with different hollow radius and wall thickness. The effect of hollow structure on the proppant density, strength and hardness is discussed. The results show that: (1) the density of hollow proppant is mainly influenced by the hollow radius, (2) the stress characteristic of hollow proppant is different from solid proppant, (3) the strength of hollow proppant increases with the increase of wall thickness and hollow radius, (4) the embedded depth of hollow proppant shows linear positive correlation with the proppant size.

Abstract: With the rapid development of urban rail transit and the increasing level of research and development, aluminum alloy materials feature excellent physical and mechanical properties, and thus an urban rail transit vehicle adopts aluminum alloy materials. Friction Stir Welding (FSW) technology is adopted in the production process of a bolster in this article and research of stress strain of friction stir welding parts plays an important role for engineering application of friction stir welding technology.

Abstract: In this paper, the theory of process failure as the basis for analysis of working conditions based on the use of production line process equipment. In ANSYS static strength theory, technology and equipment to analyze the static strength, find the weak points of equipment. For weak points and system reliability and lifetime prediction, and establish the reliability of the system platform to guide the process equipment and tooling security monitoring, to provide a scientific basis for the use of tooling and equipment reliability.

Abstract: The number of supporting dental implants is an important criterion for the surgical outcome of dental bridge fixation, which has considerable impact on biomechanical load transfer characteristics. Excessive stress at the bone–implant interface by masticatory loading may result in implant failure. The aim of this study was to evaluate the impact of the number of implants supporting the dental bridge on stress in neighboring tissues around the implants. Results of the study will provide useful information on appropriate surgical techniques for dental bridge fixation. In this study, osseointegrated smooth cylindrical dental implants of same diameter and length were numerically analyzed, using three-dimensional bone–implant models. The effect of the number of supporting implants on biomechanical stability of dental bridge was examined, using two, three and four supporting implants. All materials were assumed to be linearly elastic and isotropic. Masticatory load was applied in coron-apical direction on the external part of dental bridge. Finite Element (FE) analyses were run to solve for von Mises stress. Maximum von Mises stresses were located in the cervical line of cortical bone around dental implants. Peak von Mises stress values decreased with an increase in the number of implants that support the dental bridge. Results of this study demonstrate the importance of using the correct number of supporting implants to for dental bridge fixation.

Abstract: The paper reviews stress and deformation analysis of the thin coating. The coating covers a surface of a contact component of the trapeziometacarpal joint replacement which serves as a surgical treatment of a hand joint disease called rhizarthrosis. Motivation for this study consists mainly in the fact of occasional damage of some parts of the replacement in practice [2]. It emerged that the thin coating breaks in the location of contact which opens an effort to explore stress states of such a location depending on various input parameters. Better awareness of detailed contact conditions could lead to improvement of the replacement design and, thus, prevention from necessary reoperation.

Abstract: The role of sinusoid interface shape on the load bearing capacity of the adhesively bonded single lap joints has been investigated experimentally. The experimental results showed that the interface non-flatness can considerably influence the adhesive joint strength. The main parameters that can affect the load bearing of the non-flat joints are wave heights, wave lengths and also mechanical properties of adhesives and adherends. In this paper, the effect of wave length was evaluated as the key variable parameter. According to the experimental results for the best studied case, non-flat sinusoid single lap joints had about 51% higher load bearing compared to the conventional flat single lap joints.

Abstract: Determining mechanical properties of Bulk Metallic Glasses (BMGs) requires synthesizing of the alloys in bulk form. However obtaining metallic glass in bulk form is quite challenging due to its tendency towards crystallization. In such circumstances it is beneficial to determine the mechanical properties of materials using finite elemental analysis of microstructures. Thus, in the present investigation, using Object Oriented Finite Element Analysis (OOF2) software package, Stress-Strain analysis has been carried out on Zr₆₀Cu₁₀Al₁₅Ni₁₅ BMG to determine such mechanical properties. Specimen of Zr₆₀Cu₁₀Al₁₅Ni₁₅ BMG exhibiting three microstructurally distinct regions amorphous, partial crystalline and crystalline regions was used for this analysis. The Stress-Strain relationship have been estimated for each of the three distinct phases and the results are validated by determining the Modulus of Elasticity for all the phases and comparing it with the available experimental results from Nano-indentation test.