Value Of Equivalent Stress Research Articles

Numerical simulation study on solidification proceoss of titanium slab ingot by electron beam cold hearth melting

Abstract Titanium and titanium alloys are key basic support materials in the field of engineering technology and high technology, and are widely used in the fields of natural gas transportation, chemical corrosion, and marine development. Titanium alloy ingots are often prepared with more solidification defects such as surface cracks and cold shuts, resulting in lower utilization of titanium metal and higher cost of titanium products. The root of this is the lack of in-depth knowledge of the ingot melting and casting process, and the failure to control the thermal conditions of the billet in the molding process within a reasonable range. In this study, based on the Lagrange Euler algorithm, combined with ProCAST finite element software to establish a numerical model, revealing the solid-liquid interface morphology, the length of the transition region, and the change rule of thermal stress under the influence of different process parameters in the solidification process of titanium slab ingot. The results show that with the increase in pulling speed, the depth of the solid-liquid phase line and the width of the mushy zone of slab ingot increase, and the length of the transition region grows. With the increase in casting temperature, the depth of the solid-liquid phase line of the slab ingot decreases, and the mushy zone gradually becomes narrower. The casting temperature and pulling speed are positively correlated with the value of the thermal stress equivalent stress in slab ingots, and the probability of cracks in the corners and ingot surface is higher. This study provides effective theoretical guidance for the realization of stable mass production of high-quality titanium slab ingot.

PLA-based nature-inspired architecture for bone scaffolds: A finite element analysis

The implantation of bio-degradable scaffolds is considered as a promising approach to address the repair of bone defects. This article aims to develop a computational approach to study the mechanical behaviour, fluid dynamic, and degradation impact on polylactic acid scaffolds with nature-inspired design structures. Scaffold design is considered to be one of the main factors for the regulation of mechanical characteristics and fluid flow dynamics. In this article, five scaffolds with different nature-inspired architectures have been designed within a specific porosity range. Based on finite element analysis, their mechanical behaviour and computational fluid dynamic study are performed to evaluate the respective properties of different scaffolds. In addition, diffusion-governed degradation analysis of the scaffolds has been performed to compute the total time required for the scaffold to degrade within a given environment. Based on the mechanical behaviour, the Spider-web architecture scaffold was found to have the least deformation, and also the lowest value of equivalent stress and strain. The Nautilus Shell architecture scaffold had the highest value of equivalent stress and strain. The permeability of all the scaffolds was found to meet the requirement of the cancellous bone. All computational fluid dynamics (CFD) results of wall shear stress are in line with the requirement for cell differentiation. It was observed that the Spider-web architecture scaffold had undergone the slowest degradation, and the Giant Water Lily architecture scaffold experienced the fastest degradation.

Risk assessment on offshore pipes

Pipelines are the most frequently failed parts of oil production installations. Therefore, the safety of underwater gas pipelines became a very concerned focus in this study. This study aims to assess the risk of the pipeline due to changes in the new ABC Port shipping line that have the potential to pose a risk of pipeline damage. This study conducted a risk assessment on pipes at PT. XYZ due to anchor dropping, anchor dragging, and sinking ships. Based on the risk assessment that has been carried out on all risks, it is found that the level of risk is in an acceptable area and in the ALARP zone (As Low as reasonably Practicable Risk). Based on the results of the analysis using Ansys structural software, the maximum value of equivalent stress that occurs in the pipe due to dropped anchor can be received is no more than 0.9 of the SMYS (Specified Minimum Yield Stress) value of 4.05E+08 Pa.

Numerical simulation analysis of laser-arc hybrid welding of austenitic stainless steel

Laser-arc hybrid welding heat source has high energy density, and the temperature field is very uneven and unstable. It is impossible to systematically study the welding temperature field only through process tests. For this reason, the calculation of the thermal process of hybrid welding is of great significance to the systematic study of the temperature field of hybrid welding. In this paper, the laser-arc hybrid welding process of 8mm thick austenitic stainless steel was simulated by SYSWELD software. The results indicate that with the increase of laser energy, the melting time increases, and the peak temperature rises from 1,230°C to about 2,000°C; When the laser energy is 3.0 kW, the welding deformation reaches the minimum value of 0.68 mm, but the peak value of equivalent stress is high, which is 476.8193 MPa. When the arc voltage increases, the peak temperature rises from 1,650°C to 1,850°C, and the melting time increases. The arc voltage has little effect on the equivalent stress of the weld and has a clear impact on the welding deformation. When the voltage is 18 V, the maximum deformation reaches 2.191 mm.

Influence of Form Defect on the Mechanical Behavior and Stress Intensity Factor of Shrink-Fitted Thick-Walled Cylinders

In this research work, the finite element software, ABAQUS is used to study by simulations the influence of form defect on mechanical behavior of a shrink-fitted assembly presenting internal radial cracks. Under the action of contact pressure induced by the tightening between two cylinders, these cracks resulting from incorrect assembly operations or materials elaboration defect, can be harmful to the assembly. Various simulations were carried out in two modeling cases, taking into account the geometric parameters of defect (amplitude Df), of cylinders (thickness t) and of cracks (length a, ratio a/t). Another important parameter such as the tightening was also considered in the modeling. The first modeling relates to the case with defect, external cylinder presents an oval (elliptical) form defect and internal radial cracks. The other concerns the perfect equivalent case (without form defect). The comparison of results obtained by two models shows that form defect modifies the uniformity of equivalent stresses distribution in cylinders and increases the value of stress intensity factor (SIF) KI in cracks. Defect amplitude and tightening significantly influence the value of equivalent stress and that of stress intensity factor (SIF) <i>KI</i>.

STUDY ON THE NONLINEAR DEFORMATION MECHANICAL PROPERTIES OF A NEW TYPE OF VENA CAVA FILTER

In order to analyze the mechanical properties of a new type of retrievable vena cava filter, the Denali and Aeginsy retrievable filters are selected, and the in vivo and in vitro mechanical properties of the three types of retrievable vena cava filters are compared. The nonlinear deformation process of the filter which is pressed into the transport sheath, flicked and released into the vascular vessel is simulated by using the finite element method, and the mechanical behaviors of the filter and the blood vessel wall are analyzed. During the crimping process, the elastic strain peak value of the filter wall increases with increasing amount of grip. The maximum elastic strain peak value of the three filters is less than 8%, and the safety factor is greater than 2, which meets the strength requirement. Equivalent stress and strain on the vascular wall decreases along the direction of blood flow after the filter is opened. The peak value of equivalent stress and strain on the vascular wall corresponding to Aegisy filter is the largest, and the impact on the vascular wall is the largest. The total displacement of the three filters under the action of thrombus and blood fluids is not more than 80[Formula: see text][Formula: see text]m. The impact of the new filter on the vascular wall is smaller than that of Aegisy filter, and the total displacement after implantation is smaller than that of Denali filter. The results are valuable for the evaluation and clinical application of the new vena cava filter.

The synergistic effect of mechanical vibration for skin puncturing using polymeric microneedles

The transdermal delivery effect of polymeric microneedles can be significantly improved with the aids of synergetic vibration. The finite element simulation software ANSYS was used to explore the skin puncturing results of microneedles under different vibration frequencies. The dynamic mechanical properties of polymeric microneedles and human skin were also investigated. Meanwhile, puncturing experiments were also performed under different vibration frequencies on abdomen of female mice using polymeric microneedles with different lengths. The results showed that the peak value of maximum equivalent stress and the plastic deformation of skin were the smallest at the vibrative frequency of 200 Hz. The maximum equivalent stresses presented 20%–50% decreases during the second puncturing cycle. Moreover, the puncturing result of longer microneedles (550 μm) is much better than that of shorter ones (350 μm) under the same vibration frequency. The average bottom diameter and penetration depth of the microchannel obtained under the conditions of 200 Hz vibration and 550 μm height microneedles were 671.03 and 367.55 μm, respectively. These results provided an experimental basis to verify the effectiveness of mechanical vibration for skin puncturing.

Two-dimensional analysis method of bonding stress at steel-bamboo interface

The steel-bamboo composite structure is a novel composite system in which structural components are composed of laminated bamboo panel and cold-formed thin-walled steel using structural adhesive. Therefore, the study of the interaction and bonding failure mechanism between bamboo panel, steel and adhesive layer is the prerequisite for ensuring that the system can give full play to the advantages of materials. In this paper, a two-dimensional mechanical model for calculating the interface stress between steel and bamboo is proposed. The theoretical solution not only satisfies the boundary condition of zero bonding shear stress at the end of the adhesive layer, but also solves the normal peeling stress, which cannot be obtained in one-dimensional theory. The maximum value of equivalent stress determined in two-dimensional analysis method agrees well with one-dimensional solution with an average error of 8.92%, which proves that the two-dimensional analysis method is feasible and reliable.

HDPE based polymeric nanodiamond nanocomposite for total knee arthoplasty: A finite element based approach

The current investigation orients towards the finite element analysis of polymeric-based knee implant along with nanodiamond nanocomposite spacer. The spacer is a High-Density Polyethylene (HDPE) hybrid nanocomposite reinforced with nanodiamond as a filler material at 0.1 wt%. The structural analysis of the spacer is performed in ANSYS Workbench 19.0 at different flexion angles (i.e., 0, 15, 30, 45, and 700) with a load of 1000 N. The outcomes of the results confirmed that the peak value Equivalent Von-Mises stress (MPa) and Contact Pressure (MPa) for the spacer are 25.978 MPa and 35.817 MPa, which occur at 450 flexion angle of the femoral component. It is also noted that with HDPE/0.1ND composite as spacer material, the value of maximum Equivalent Von-Mises stress is lower than the yield stress, which makes HDPE/0.1ND an ideal material for the spacer to be used as knee arthroplasty implant material.

Performance and thermal stresses in functionally graded anode-supported honeycomb solid-oxide fuel cells

Enhancing the performance of anode supported honeycomb solid-oxide fuel cells via operating at higher temperatures is of great interest. However, working at a higher temperature leads to a significant rise in thermal stresses over the allowable limit. Thus, in the current study, functionally graded electrodes are considered to avoid cell failure due to higher thermal stresses. To assess the cell performance and thermal stress distribution, a theoretical investigation of a solid-oxide fuel cell with a honeycomb configuration using functionally graded electrode compositions is conducted through a comprehensive 3D model. The developed model includes the charge transport, mass and momentum transport, energy conservation, electrochemical reaction kinetics, and elastic stress. The model is numerically simulated and validated with the available experimental data. Results indicate that using functionally graded electrodes with grading index m = 1 significantly improves the fuel cell's performance, with an improvement in power density reaching around 60%. In addition, the most beneficial improvement is to reduce thermal stresses at elevated temperatures, for which the maximum value of equivalent stress is reduced to 85% less than the conventional electrode at a temperature of 1150 °C. Accordingly, the fuel cell's maximum power density can be obtained by operating at elevated temperatures with safe thermal stresses. These improvements are particularly attractive for applications requiring compact, reliable, and high-power devices based on fuel cell technology.

Designing, modeling, and structural analysis of a newly designed double lobe camshaft for a two-stroke compressed air engine

With the rapid increase of urbanization and industrialization, the energy demand has expeditiously risen. The natural resources are limited and will be extinct in the next few years. If the depletion of fossil fuels continues at the same rate as it is, the world will suffer from severe energy scarcity in the nearer future. Therefore, to reduce the dependency on liquid-based petroleum fuels, there is an urgent need for alternative fuels that could compensate for diesel demand and reduce harmful emissions from the atmosphere. The paper presents the designing, modeling, and analyzing a newly designed double lobe camshaft for a compressed air engine. In this study, a 100-cc Four-Stroke SI engine manufactured by Bajaj Auto, an Indian motorcycle manufacturer, was used and tested on compressed air. The engine was modified from a conventional four-stroke to a two-stroke engine by designing a new camshaft for opening the valves at different timings. The newly designed camshaft contains axisymmetric double lobes on both the inlet and outlet cams. Thus, in one complete revolution of the crankshaft, both the valves open once, resulting in one power stroke and one exhaust stroke, eliminating the compression and intake stroke. Any modifications in the camshaft cause various changes in the stress distribution and deformation along the shaft, which should be studied to provide us vital information about the life and effectiveness of the new modified camshaft. The objective is to determine the new valve lift profile, deformation, and equivalent (Von-Mises) stress under loading conditions on the double lobe camshaft. The designing and modeling of the camshaft are done in SOLIDWORKS 2020, and structural analysis is carried out in ANSYS 2020. The maximum total deformation resulted from the analysis comes out to be 5.72 × 10-4 mm, and the maximum value of equivalent stress evaluated is 31.17 MPa.

Dynamic heating and thermal destruction conditions of quartz particles in polydisperse plasma flow of RF-ICP torch system

Numerical simulation of turbulent mixing process of polydisperse quartz particle (particle size distribution in the range of 0.1–0.4 mm) flow with Ar and Ar-H2 plasma generated by radio frequency inductively coupled plasma (RF-ICP) torch has been made. An approximate two-stage approach has been proposed to calculate the spatial–temporal distributions of temperature and resulting thermal stress in quartz particles during dynamic heating in polydisperse plasma flow. The influence of working gas compositions, particle size distributions, injection angle and flow rate of carrier gas on the thermal destruction conditions of quartz particles has been determined under different particle feed rates. It is found that all the solid quartz particles (0.1–0.4 mm) could be thermal destructed without overheating in RF-ICP torch system, when the hydrogen volume fraction in working gases is more than 1.5%–2% and particle feed rate is in a certain range. The values of the maximum and minimum feed rates have been determined under different hydrogen volume fractions. An optimal particle injection angle and flow rate of carrier gas is found around 50°–60° and 160–220 slpm, under which the value of maximum equivalent thermal stress in quartz particles is highest.

Computation of Stress Distribution in Hydraulic Horizontal Propeller Turbine Runner Based on Fluid–Structure Interaction Analysis

In the hydro-turbine operation, the kinetic energy of flowing fluid is converted into mechanical energy. In the turbine operation, fluid induces hydraulic load that not only provides a useful mechanical driving torque on the turbine shaft but also causes deformation in turbine components and stress distribution that might induce a structure failure. Structural failure in turbine component decreases performance as well as increases the maintenance cost of hydro-turbines. In this paper, fluid–structure interaction model is used to investigate the stress distribution and total deformation of hydraulic horizontal propeller turbine runner (HHPTR) with different flow velocities, blade widths and blade wrap angles. The results showed that the effects of blade wrap angles and blade width significantly influence the performance and structural strength of the HHPTR. Maximum turbine performance was observed at blade wrap angle of 100° and blade width of 2 mm. It was also found that the maximum value of equivalent stress near the runner hub is 59.54 MPa at blade wrap angle 100°. Similarly, the maximum value of total deformation in HHPTR is 0.7689 mm near the runner blade edges at blade wrap angle 60°.

Compressive behavior of auxetic structural metamaterial for lightweight construction using ANSYS static structural analysis

Metamaterials are the class of man-made cellular structures that are intended to improve the energy absorption ability without an expense on its weight. The current investigation focuses on modeling and compressive simulation of three types of basic metamaterial (i.e Diamond, Auxetic and Hexagon) and its hybrids (i.e Auxetic-diamond, Auxetic-hexagon and Diamond-hexagon) with Ansys 19 simulation software. All the six auxetic metamaterials are simulated by assuming Polylactic Acid (PLA) material. At 0.1 MPa the maximum equivalent von-Mises stress was evident during the compressive analysis of auxetic-diamond hybrid structure. For auxetic-diamond hybrid structure higher energy absorption of 40 mJ was noted. It was observed to decrease by 67, 62, 75, 25 and 40% for auxetic, diamond, hexagon, auxetic-hexagon and diamond-hexagon respectively. The higher value of equivalent von-Mises stress and higher energy absorption is a manifestation of stiffest structure. The deformation results during simulation test confirmed that the basic auxetic structure and its hybrid absorb more energy. The hybrid auxetic metamaterials are the new class structural elements that exhibited extraordinary energy absorption ability.

Numerical simulation and experimental investigations on a three-roller setting round process for thin-walled pipes

In order to reveal the process principle of three-roller setting round process and optimize the setting round strategy, the three-roller setting round process is simulated and experimented. The results show that there are three positive bending regions and three reverse bending regions in the cross section of pipe in the setting round process. The absolute value of equivalent stress and equivalent strain not only decreases from both ends to the geometric neutral layer along the thickness direction of pipe but also decreases from the center of each positive and negative bending region to both sides along the circumferential direction of pipe. The distribution of maximum stress and minimum stress conforms to the characteristics of pure bending deformation in the setting round process. The direction of tangential stress is the direction of main stress, and the direction of tangential strain is the direction of main strain. The geometrical dimensions of pipe do not change in axial and radial directions. The residual ovality of pipes with different initial ovality is basically the same, which proves that the uniform curvature theorem of reciprocating bending is correct. The residual ovality of pipes decreases with the increase of the reduction. With the increase of the relative thickness of pipes, the optimum reduction of pipes decreases gradually. Comparing experimental results with simulation results, the residual ovality of pipes can be less than 0.2%.

Thermal and structural analyses of an internal combustion engine piston with suitable different super alloys

Abstract The objective of this paper is to study the thermal and structural performance of piston by changing the gas pressure conditions with different super alloys. Piston model is created using CATIA and analysis is done in ANSYS 16. Boundary conditions used are load, support, convection coefficient and heat flow. Different super alloys are used as materials in the present study that have dissimilar thermal conductivities and densities. For Alcoa Deltalloy, the maximum temperature occurred is low for the same heat flow input as compared to other materials used. It also has less deformation in spite of higher thermal expansion coefficient. NIMONIC alloy showed the lowest equivalent stress among all the super alloys considered. In case of combined thermal and structural load, Alcoa Deltalloy showed the increasing trend of deformation, but non-linear. UNS S20103 and NIMONIC alloy 81 showed decreasing trend of deformation as pressure is increased. The value of equivalent stress in Alcoa Deltalloy is found to be very less as compared to other two super alloys. On the basis of observations, it is clear that Alcoa Deltalloy is the best material for use of engine piston that can have better operating conditions in terms of less failure and long life

The rolling contact research of three dimensional wheel-rail based on finite element analysis

In this paper, wheel-rail contact model was established and analyzed, some useful results were obtained. The results show that In the early stage of wheel-rail contact, the wheel-rail contact pressure increases gradually and the contact point shape changes from regular polygon to irregular polygon in the process of wheel approaching rail joint. The equivalent stress and elastic deformation trend of the rail are basically the same, both of which decrease rapidly and then slowly increase. The plastic deformation of the rail gradually increases and accumulates, and the stress concentration area occurs at the side of the rail joint. When the wheel starts rolling, the equivalent stress of the wheel gradually decreases at first, and then increase. The peak value of the maximum equivalent stress occurs at the joint where the wheel reaches the rail.

Conceptual design and finite element analysis of a high inclusion dough shaping machine using 3D‐computer aided design (CAD) (SolidWorks)

AbstractDue to unavailability of omit suitable machine to shape oat base cookies dough with large inclusion, inconsistency in size is a critical issue. Thus, a dough shaping machine is needed to improve the quality of the final product. The objectives of this research are to develop conceptual designs of a high inclusion dough shaping machine and to perform finite element analysis on the important part of the machine. The methodology including extraction of the design layout of the machine, development of the schematic drawing and wireframe model, the performance of stress and total deformation, and production of a complete drawing for fabrication purpose. Under finite element analysis, result of the maximum allowable stress was compared with the calculated static component strength against crack. Based on the analysis using SolidWorks, the maximum equivalent stress of the roller is 0.3469 MPa with maximum total deformation is 2.617 ⋅ 10−4 mm. The value of maximum equivalent stress is way too small as compared to that of the calculated static component strength against crack which is 15.31 MPa. Hence, the material used for the roller was found to be able to support the weight of dough without crack and avoid critical deformation during the production process.

Stress and Crack Simulation on Axle Housing Mitsubishi L300 Pickup Car using Finite Element Method

Axle housing in pickup cars receives the main load that is direct or indirect. The direct load referred to is the weight of the load and the weight of the vehicle itself, while indirect loading can be in the form of twisting and bending moments. Due to the load experienced by the axle housing will result in deformation, cracking, and even fractured. Based on the case of failure, an analysis of the axle housing was performed which covers two things, namely stress analysis and crack analysis. Axle housing analysis uses the Finite Element Method (FEM) approach, through the Ansys software. The result of stress analysis shows the maximum value of Equivalent (von-mises) Stress is 14,356 MPa, the Maximum Principal Stress is 14,977 Mpa, and the Maximum Shear Stress value is 7,5471 MPa. The result of crack analysis shows the maximum value of J-Integral is 0.00051126 mJ / mm2 and the maximum value of SIFS (K1) is 10.823 MPa.mm0.5.

Influence of three-wall osseous defects on periodontal ligament stress with three-dimensional finite element analysis

This study aims to explore the influence of three-wall osseous defects on periodontal ligament stress under normal occlusal forces. A finite element model for mandibular total dentition, periodontal ligament and alveolar bone was created based on cone beam computed tomography (CBCT) DICOM images. Mesial or distal proximal three-wall osseous defects at varying depths (namely, 1/3, 2/3 and 3/3 of the root) were simulated by modifying the elastic modulus of elements within the defects area. Occlusal forces with an angle of 45° to the long axis of the tooth were applied to the finite element model. In addition, the equivalent stresses of the periodontal ligament were analysed. In the case of no bone defect, the mean value of the periodontal ligament equivalent stress of 14 teeth was 5.71 MPa. The equivalent stresses of the periodontal ligament at different depths (namely, 1/3, 2/3 and 3/3 of the root) were 6.61, 7.14 and 7.42 MPa, respectively. With increasing depth of the osseous defects, stress on the periodontal ligament increased considerably, and the initial stress increment was greater than that of a later stage. Periodontal ligament stresses with mesial proximal three-wall osseous defects (at depths of 1/3, 2/3 and 3/3 of the root) were 6.62, 7.19 and 7.51 MPa respectively. Periodontal ligament stresses with distal proximal three-wall osseous defects (at depths of 1/3, 2/3 and 3/3 of the root) were 6.60, 7.10 and 7.33 MPa, respectively. For three-wall osseous defects located in the mesial surface and distal surface, a significant difference in periodontal ligament stress was lacking. In the case of the same absorption depth, the size relationship of periodontal ligament stress was in the following order: premolars>molars>incisors>canines. Shallow three-wall osseous defects will likely cause a notable loss in strength of the periodontal ligament. Therefore, teeth with three-wall osseous defects should become the focus of clinical research. Treatment for these teeth should be administered as early as possible.