Von Misses Research Articles

Barge’s study under impact loads

The aim of this paper is to present a method of increasing the safety of inner water navigation. It concern on improving the structural resistance of a barge during design process. Numerical structural analyses of the deck and the board are purposed to solve the problem. Different values of friction coefficient steel on steel are considered as input data. Naval structure’s behaviour is analysed using the area and the volume values of the struck surfaces. The post-processing of data shows an influence of the friction coefficient on Von Misses stress of the deck’s structural components. This method also allows evaluation of the barge damages.

Influence of bone quality on the mechanical interaction between implant and bone: A finite element analysis

ObjectivesTo evaluate the influence of bone type in terms of bone density and cortical bone thickness, on the stresses induced by two implants under compressive and oblique loads. MethodsA numerical simulation technique based on the finite element method was applied. Two implant types (M-12 and Astra Tech) were introduced in a model matrix whose geometry was extracted from a real CBCT radiograph of the posterior mandibular region. The Young’s module and Poisson’s coefficient of the bone qualities described by Misch were calculated. Loads with amplitude of 400 N were exerted in two directions: compressive and 15° oblique to 5 mm above the uppermost part of the implant. ResultsThe von Misses variant was analysed. Both implant types presented greater tension in the ​​cortical bone area than in the ​​trabecular bone region under compressive loading. For the oblique load condition, the stresses obtained in the cortical zone were significantly higher than those registered as a consequence of compressive loads in both implant types. ConclusionsRegardless of bone type, the M-12 implants presented lower tensions in the cortical bone than did the Astra implants. The tensions recorded for D3 and D4 bone types in the trabecular zone surrounding the M-12 implants were greater than those recorded for the Astra implants. Clinical significanceFor both compressive and oblique loads, good mechanical behaviour was observed. The decrease in bone quality determines a worse stress distribution, and the cortical bone is overloaded. An efficient distribution of the forces may increase the implants’ longevity.

Dynamic Analysis of UAV’s Motor Support Bar Length Control System

UAV (Unmanned Aerial Vehicle) can be described as aircraft that do not need any presence of pilots inside it. Basically, UAV is come out in a small aircraft so that the aircraft can be easily controlled by the people from afar[1]. The UAV’s motor support bar length control systems are the UAV’s control systems that move according to the variable arm length movement and also a constant revolution of the propeller speeds. The purpose of the study is to run the dynamic analysis at the UAV’s motor support bar length control systems and also to enhance the UAV’s mathematical modelling by using the SOLIDWORKS® software which involved in using both CAD and CAE systems[2]. The detailed design is used SOLIDWORKS® software to conduct the static and dynamic analysis of UAV’s motor support bar length control systems. The design is restricted to the arm due to the critical part that has the highest vibration at the UAV’s motor support bar length control systems. The results that obtain from the study from the static and dynamic analysis are the displacement of the motor, Von Misses stress of the arm, and also the resonance frequency that will give the modes shape to the systems.

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

The aim of this systematic review is to provide an overview of finite element analyses comparing standard and short dental implants concerning biomechanical properties and to detect the most relevant parameters affecting periimplant stress concentrations. After screening the literature and assessment of studies, 36 studies were included in this review. Eighty-three percent of the studies state that short dental implants have to bear higher stress concentrations compared with standard length implants. At the same time, 44% of articles note that implant diameter can be considered a more effective design parameter than implant length to reduce stress concentrations and to avoid an overload of periimplant bone. Regardless of implant dimension, in all studies, the highest stress concentrations are found in the cortical section around the upper part of the implant. Unaffected of bone quality, implant diameter is found to play a key role to minimize periimplant stress concentrations. Concerning stress reduction implant length gains increasing relevance with decreasing bone density. Furthermore, splinting of short implants constitute an appropriate tool to avoid crestal overloading.

Propagation of a Crack in a Composite Plate

In this paper, a model of a composite plate with a central elliptical cut-out and with an initial fissure was subjected to a tension load in the finite element method (FEM) software Abaqus to observe the propagation of that crack during a certain amount of time that elapsed in the FEM analysis. Due to symmetry, only half of the plate was modeled, as a shell, and the extended finite element method (XFEM) was used for the crack. The material properties that were assigned to the plate were taken from the database of the Ansys Mechanical software. In the vicinity of the crack a finer mesh was applied to be able to better observe the evolution of the fissure and the changes of the Von Misses stress graphs for each time step of the analysis.

Optimal threshold for Pareto tail modelling in the presence of outliers

The Pareto distribution is widely applied in many areas of studies such as economics and sciences. An important issues related to Pareto tail modelling is to determine the optimal threshold of the Pareto distribution. One of the methods used for determining the optimal threshold of Pareto distribution is by choosing the threshold that minimizes the goodness-of-fit statistics found based on empirical distribution function (EDF). This study involves determination of the shape parameter of the Pareto distribution using the maximum likelihood method and robust method based on the probability integral transform statistics. In addition, given the particular estimates of the shape parameter, comparison of the performance of several EDF statistics, namely, Kolmogorov–Smirnov, Kuiper, Anderson–Darling, Cramer–von Misses and Watson statistics in determining the optimal threshold in the presence of outliers is studied based on Monte Carlo simulation. Since the EDF statistics are found smallest for Kolmogorov–Smirnov or Kuiper statistics, these two EDF statistics outperformed other EDF statistics considered. The findings are illustrated using a sample of household income data of the Malaysian population. The optimal threshold found can be used to classify the high income earners in Malaysia since Pareto distribution is one of the most frequently used model to describe the upper tail of income distribution.

Determination of the Structural Characteristics of Microalgal Cells Walls under the Influence of Turbulent Mixing Energy in Open Raceway Ponds

Turbulent flow mixing is essential in optimizing microalgal cultivation in raceway ponds. Microalgal cells are however highly sensitive to hydrodynamic stresses produced by turbulent mixing because of their small size. The mechanical properties (wall deformation and von Misses stress) of the microalgal cell wall structure under the influence of turbulent mixing are yet to be explored. High turbulence magnitudes damage microalgal cell walls by adversely affecting their mechanical properties which consequently destroy the microalgal cells and reduce the biofuel production. Therefore, such a study is required to improve the biofuel productivity of microalgal cells before their cell wall damage in raceway pond. This study developed a novel fluid–structure interaction (FSI)-based numerical model to investigate the effects of turbulent mixing on the cell wall damage of microalgal cells in raceway ponds. The study investigated microalgal cell wall damage at four different locations in a raceway pond in consideration of the effects of pond’s hydrodynamic and geometric properties. An experiment was conducted with a laboratory-scale raceway pond to compare and validate the numerical results by using time-dependent water velocities. Microalgal cell wall shear stress, cell wall deformation, and von Misses stress in the raceway pond were investigated by considering the effects of aspect ratios, water depths, and paddle wheel rotational speeds. Results showed that the proposed numerical model can be used as a prerequisite method for the selection of appropriate turbulent mixing. Microalgal cell wall damage is high in shallow and narrow raceway ponds with high paddle rotational speeds.

Analisis tegangan pada batang utama mekanisme bukaan payung raksasa

Spacious areas as venues for events such as weddings, gatherings, musical performances, bazaars even as parking lots, need to be protected from climate change. Therefore, it is necessary to develop the design of a giant umbrella axle mechanism measuring 12 x 12 meters with a height of 8 meters. This paper describes and stresses the stress analysis on the main bar of the giant umbrella opening mechanism. The result of modeling on the stem is presented in the form of stress contour, factor of safety (FOS), and displacement. The largest working voltage is 2 MPa in the connection area, but this voltage is still low when compared with ASTM A36 rod material structure or equivalent to SS-41 which has a yield strength of 100 MPa. The low voltage von misses are relevant to FOS values that generally reach 100 or more. The largest displacement value is in the center of the stem, which is 0.3 mm. Thus, the modeling results are able to withstand a load of 1 ton.

STRESS CALCULATION FOR RECTANGULAR PLATE USING SIMPLIFIED ANALYTICAL METHOD

Plate stress calculation is a fundamental problem of strength of material. Accurate analytical solution needs rigorous analytical calculation of solving differential equations. Such calculation gives values bending moment and stresses at all points. In the simple analytic calculation mentioned here we have calculated bending moment across most critically loaded section. We have first selected the most critical section of the plate where the max bending moment and max stresses are expected to occur. Then we have calculated bending moment (average) across that section using simple methods of equilibrium of forces and moments. Thereafter we have calculated stresses corresponding to that bending moment using strength of material formula. FEM analysis using ANSYS is carried out to find out exact max stresses (Von Misses). Four different combinations of support condition and load cases are done. We have checked the error in such approximate calculate analytic calculation.

Determinación del estado tensional de un invernadero tipo capilla en áreas de clima tropical

El presente trabajo analiza la estructura de un invernadero tipo capilla, el que a través de un modelo simplificado es sometido a vientos tropicales de 120 km, determinándose el estado tensional que presenta al actuar cargas de vientos en dos direcciones (lateral-frontal). En la investigación se muestran las tensiones Von Misses asociadas a los esfuerzos que provocan las cargas de vientos sobre cada elemento, comparándose los resultados con el límite elástico del material empleado, además se muestran los desplazamientos que ocurren en los nodos producto de la acción de las cargas, lo anterior se logra mediante el uso del programa RAM Advanse versión 5.1 aplicándose dos combinaciones de cargas que consideran el peso propio y las cargas de viento con sus respectivos coeficientes de mayoración, finalmente se presentan las conclusiones derivadas del análisis de los resultados obtenidos.

Simulation Based Structural Analysis of an Oil Tanker Bulkhead

Traditional way of ship structural design is to follow the rule books of classification societies. These rule books certainly ensure enough structural integrity of ships. But in this age of scientific and engineering progress, reliable structural analysis programs and tools are available. This paper shows how these programs can be used to verify classification society rules and to accurately design in small details. A bulkhead of an oil tanker is chosen for this investigation. The analysis is done taking Von Misses stress and factor of safety as design criteria. The results of this investigation aim to help the traditional structural engineers to design ship structures in a more effective and optimized way.

Design Optimization of Rotor Lock Disc for Horizontal Axis Wind Turbine Generator

This study presents design optimization of rotor lock disc in the generator rotor which was analyzed by applying the respective lateral force taken from machine load calculation for a 2.5 MW permanent magnet direct-drive wind turbine generator. The machine load calculation result was derived from GH Bladed software output. The maximum tensile stress, internal stresses such as von Misses, maximum displacement and corresponding safety factor were calculated in terms of theoretical stress concentration factor due to discontinuity or change in cross-section in the region where the rotor lock is present. The rotor lock disc configuration was optimized to satisfy a safety factor of unity using exhaustive search method and Cosmos works software. Calculation results indicated that the safety factor of rotor lock disc with 40 mm thickness failed when design lateral force taken from the extreme load of rotor locking torque was used. However, the safety factor of the optimized rotor lock disc with 60 mm thickness has been improved when the inner radius and the total arc subtended angle are properly identified.

Theoretical and Experimental Stress Analysis of Cam With Simple Harmonic Motion

Cams are considered as one of the most important mechanical components that depends the contact action to do its job and suffer a lot of with drawbacks to be predicted and overcame in the design process. this work aims to investigate the induced cam contact and the maximum shear stress energy or (von misses) stresses during the course of action analytically using Hertz contact stress equation and the principal stress formulations to find the maximum stress value and its position beneath the contacting surfaces. The experimental investigation adopted two dimensions photoelastic technique to analyze cam stresses under a plane polarized light. The problem has been numerically simulated using Ansys software version 15 as FE solver and depending on Lagrange and Penalty contact algorithm. The effect of cam geometry, characterized by some parameters such as follower radius, face width, rise and return angles, and modulus of elasticity on the contact stress is investigated aiming to minimize the induced stresses.
 

Design of a Mixed Flow Pump Impeller Blade and its Validation Using Stress Analysis

The failure of blades of a mixed flow pump impeller is generally due to excessive stress development. In order to avoid such situation one should design the blades taking into consideration the Von Misses stress distribution in the impeller blades. In this present work design and stress analysis has been carried out on mixed flow pump impeller blades having different positions in the meridional annulus. The maximum Von Misses stress distribution was compared among the different blade positions. The inlet inclined blade position in the meridional annulus was found to be more suitable than the trapezoidal one as the Von Misses Stress distribution was lesser for inlet inclined blade.

General Lifetime Damage Model for Glass Fibre Reinforced Epoxy (GRE) Composite Pipes under Multiaxial Loading

This paper presents the modelling of a general lifetime performance for glass fibre reinforced epoxy (GRE) composite pipes similar to the well-known Tsai-Hill interactive failure criterion. Tsai Hill criterion is based on the Von Misses distortional energy criterion which was modified to satisfy the orthotropic nature of GRE composite pipes. The effects of stress developed in each ply from ultimate elastic wall stress (UEWS) test were expressed in a single quadratic term of axial and hoop stress through laminate theory. The term then solved to produce limits with respect to axial and hoop stress, which represented in a graphical form of failure envelope. The modelled envelop shows a good agreement with experimental data from the multiaxial UEWS test of ±55° GRE composite pipes. This indicates that such model can be used to predict the long-term performance of GRE pipes under combine loadings.

The Design and Analysis of Bracket of Scraper Part of Coal Mine Underground Horizontal Extension Transfer Machine Based on Solid Works

The paper aims to design a kind of bracket of scraper part of coal mine underground horizontal extension Transfer Machine perfectly, based on Solid Works. And we would like to perform numerical simulation for the bracket, furthermore to optimize the transect parameters and achieve that to reduce the weight of the bracket. At last, through optimization design, we prefer to reduce 4.5% in Von Misses press and 15% in weight. In this way, we can offer a useful reference to design the bracket of scraper part of coal mine underground horizontal extension Transfer Machine.

Combined plasticity and creep analysis in 2D by means of the boundary element method

Abstract This work presents a formulation to make a combined analysis of plasticity and creep in two-dimensional (2D) using the Boundary Element Method. This new approach is developed to combine the constitutive equation for time hardening creep and the constitutive equation for plasticity, the latter based on the Von Misses criterion and the Prandtl–Reuss flow. The implementation of creep strain in the formulation is achieved through domain integrals. The creep phenomenon takes place in the domain which is discretized into quadratic quadrilateral continuous and discontinuous cells. The creep analysis is applied to metals with a power law creep for the secondary creep stage. The results, obtained with reference to three models, show a good agreement when compared to those published in the literature. This finding shows that the Boundary Element Method is a suitable tool to deal with combined nonlinear problems.

Connector design in a long-span-fixed dental prosthesis: A three-dimensional finite element analysis

The goal of every prosthetic management is to simulate nature and be in harmony with nature within the physiological limits. The occlusal forces on a fixed dental prosthesis are transmitted to the surrounding structures through pontics, connectors and retainers and more stresses are seen at the connector region. To analyze the stress patterns in cast and soldered connectors between the two pontics and between the retainer and pontic of a four unit fixed dental prosthesis on axial and non axial loading and also to observe and ascertain the need to modify the design of the rigid connectors. Subsequently four models each of cast and soldered connectors with cylindrical and triangular design, of dimension 3 × 4 mm and thickness 0.5 mm was designed for the study. The first premolar and second molar were considered as the abutments and 2 nd premolar and 1 st molar as the pontics. The analysis was done using ANSYS version 8.0 software and by placing axial and non-axial load of 40 Newtons each. Von Misses stresses were observed at the connector region between the two pontics, especially in the cervical region. The cylindrical cast connectors showed less stress in comparison to triangular design and the difference in the stress distribution of cast and soldered connectors were marginal. The occlusal forces on a fixed dental prosthesis are transmitted to the surrounding structures through pontics, connectors and retainers with maximum stresses concentrated at the connectors. Hence this three-dimensional finite element analysis study investigated stress distribution in a four unit posterior fixed dental prosthesis, having cylindrical and triangular connector designs.

Research on stress distribution between wires of single thigh steel strand

A three-dimensional contact model of 1×7 steel strand was established. Contact point was searched by Splitting-pinball algorithm, and Augmented-Lagrangian algorithm was applied for analysis of contact loads. The exerted tensile loads to the model were analyzed using finite element method. After analyzing calculation results, the laws of steel wire stress distribution in axis direction and in its cross-section were found. Friction coefficients were set as 0.10, 0.11, and 0.12, respectively, to obtain the influence law of friction coefficient to steel wire stresses. Research result shows that friction coefficient has significant influence on the shear stress of steel wire. Analyzed the calculation results of steel strand with five different lay pitch multiples and got the influence law of lay pitch multiple to the stresses of steel wire in steel strand. The Von Misses stress of steel wire increases following with the increasing of lay pitches multiples, but the increment value is not very prominent. The shear stress of steel wire decreases following the increase of lay pitch multiple, and the changing amplitude is large when lay pitch multiple is small. Finally, carried out a steel strand tensile deformation test and the consistency of test results with the calculation results shows that the selected model is reasonable.

3D Numerical Simulation of Point Impact Breakage of a Glass Ball

Based on the 3D plane impact and 2D MCA numerical simulation, the 3D ANSYS/LS-DYNA software is applied to conduct numerical simulations on two kinds of impact breaking process of a glass ball, during which spallation phenomenon occur. The Von Misses stress of each node changes with the time as the result of the stress waves spreading, reflecting and overlapping within the material. The stereograms and profiles from the simulation results reveal that the stress of each node changes with the time. By comparing the simulation results of plane impact and 2D point impact, differences and similarities between these processes are illustrated in this paper, which reflects the complexity of mechanics in the processes.