Static Stress Analysis Research Articles

The tension failure mechanisms of composite stepped bonding repairs and joints for the aircraft primary load-bearing structures

Stepped and scarf topology are still the preferred choices for repairs and joints of composite primary load-bearing structures. The stepped bonding scheme is easy to be implemented in real engineering process. The precise stress distribution, load capacity, damage mode and failure mechanism are not adequately clear. This paper adopts static stress analysis of FEM (Finite Element Method), experimental studies and CDM (Continuum Damage Mechanics) to reveal the tension failure mechanism for composite stepped bonding structures. In the static stress analysis, the mesoscale FEM model considered the adhesive thickness was created. It investigated the detail stress distribution and concentration of the step topology adhesive. Then seven specimens with tensile load were studied experimentally through relation of load-deformation and the appearance of damage. For more details, the adhesive damage was simulated by using CZM (Cohesive Zone Model) which includes the mix-mode fracture of normal force and sliding shear force. The process of damage propagation evolution can be clearly observed in the simulation results. The damage initiates at the vertical location of steps adhesive and propagates to the horizontal overlaps adhesive. Simulation for predicting the ultimate load capacity coincides with experiments. This paper’s work will be useful for designing and analyzing the full composite materials airframe and wing repaired by stepped bonding technique.

Modeling and Simulation of Thermally-Induced Static Stress on A Heat Exchanger

The ultimate purpose of any stress analysis is to allow the comparison of the developed stresses, strains, and deflections with those that are allowed by the design criteria. Heat exchanger is a thermo-fluid machine used to transfer heat between two or more fluids. Depending on the goal for which the designer intends to achieve, heat exchangers, therefore, could be used for both heating and cooling processes. This work is about Static Stress analysis to determine or estimate the stresses, displacements, strains, including the factor of safety of the Heat Exchanger (HE) and its designed carrying or working capacity. This analysis predict failure by evaluating whether or not the Heat Exchanger will be able to withstand the internal stresses due to its maximum loading and working capacity. The summation of the masses of individual component inside the shell and tube heat exchanger was generated by the material library in the software using the provided model geometry and the resultant data was used to run the simulation. The maximum Stress experienced by the Heat Exchanger according to the simulation result is 1.254e-01 N/mm2 (MPa) which is far less than the yield strength of the material used in building it (1.72369e+08 N/m2). Hence the Heat Exchanger will survive the maximum loading and working capacity according to von Mises Stress analysis and with a significant factor of safety. For the numerical simulation and analysis of heat exchanger, the static stress processes is successfully captured. The simulations suggest that a critical stress level may exist beyond which a minor disturbance can induce a catastrophic damage.

Statička analiza napona sistema suspenzija za vozilo sa solarnim pogonom

Suspension systems are designed aiming at providing adequate handling, road holding, comfort and vibration control to a terrestrial vehicle. Being an important issue not only for regular road models, suspension design is a matter of concern that also regards solar electric cars, in which, due to limited power supply, stabilization and energy conservation are of utmost importance. Considering three basic types of suspension widely adopted in road vehicle design, this study presents a preliminary comparison among MacPherson, double wishbone and leaf spring systems, aimed at pointing out the most appropriate design for the solar-powered vehicle hereby considered. It includes a finite element static stress analysis, performed with parametric values for a quarter-car model.

Two bay crack arrest capability evaluation for metallic fuselage

Transport aircraft is a highly complex structure. The aircraft fuselage shell is composed of stressed skin, longitudinal stringers, and circumferential frames. The skin is connected to the stringers and frames mostly by rivets. The fuselage has a number of riveted joints and is subjected to a major loading of differential internal pressurization. When the fuselage is pressurized and depressurized during each take-off and landing cycle of aircraft, the metal skin of fuselage expands and contracts to result in metal fatigue. Due to the presence of a large number of rivet holes, the fuselage skin has a large number of high-stress locations and these are locations of potential crack initiation. The wide-bodied transport aircraft are designed to tolerate large fatigue cracks. This project focuses attention on damage tolerance design of a fuselage structure of transport aircraft. In this project, the stress intensity factor, quantifying the intensity of the stress field around a crack tip for a longitudinal crack under the pressurization load is studied. The objective of this project is to investigate crack initiation, crack growth, fast fracture and crack arrest features in the stiffened panel. The longitudinal crack is initiated from the rivet hole and stress intensity factor is calculated using modified virtual crack closure integral (MVCCI) method at each stage of crack propagation. In order to arrest crack propagation which is the capital importance of tear straps are used, which prevent the further crack propagation. In this project, the linear static stress analysis of the stiffened panel of a fuselage is performed using MSC NASTRAN solver. The pre-processing of the model is done by using MSC PATRAN software.

Static and dynamic stress analysis of flat bottom-bamboo reinforced concrete silo for rough rice storage.

Concrete silos are one of the most robust and reliable structures for grain storage in tropical countries. This study analysed the structural behavior of a low cost, flat bottom bamboo-reinforced concrete (BRC) silo for rough rice storage. This research included the design and development of a BRC silo in accordance with the guidelines mentioned by the Indian Standard (IS) codes. The Finite Element Method was employed to develop the stress profile in the silo walls under “grain at rest” and “grain filling” conditions. The results obtained were further compared with experimental results, classic silo theories (Janssen’s theory) and standards of different countries in the world. The numerical technique gave stress magnitudes very close to those of the experimental results. The classic theories as well as the standards of different countries predicted an over estimation of the magnitude of stresses in the BRC silo. This would result in extra cost of construction of BRC silos. The study also suggested that the vertical stresses were most predominant under static and filling conditions. Maximum stresses were developed at the silo bottom. This study is expected to aid the development of economical silos with minimum wall thickness and material requirement which are ideal for on-site construction and use by smallholder farmers.

A new hybrid mount actuator consisting of air spring and magneto-rheological damper for vibration control of a heavy precision stage

In this study, a hybrid mount actuator featuring both the air sprung and magneto-rheological (MR) damper is devised for the vibration control of precision manufacturing or inspection stages. After briefly describing the structural configuration of the precision stage, both static and dynamic stress analyses are carried out to determine the appropriate size and weight of the hybrid actuator. The air spring is designed considering the static load of the stage and assuming adiabatic process conditions between the actuator and the surrounding space. The MR damper is designed considering the controllable range of the field-dependent damping force based on the Bingham model of MR fluid. Then, four hybrid mount actuators are manufactured followed by the identification of the field-dependent damping force characteristics. Subsequently, four actuators are installed into the precision semi-conductor inspection stage to evaluate the vibration control performances. In this study, a simple but very effective proportional-integral-derivative (PID) controller is designed and empirically realized in order to drive the hybrid mount actuators. It is demonstrated that by activating the proposed hybrid actuators, the unwanted vibrations of the precision stage are substantially reduced in the operating frequency (up to 30 Hz) and fast settling time is achieved in the transient vibration.

Failure Analysis of Primary Suspension Spring of Rail Road Vehicle

WAG-9-type electric rail vehicle, of Indian Railways’ fleet used for goods train hauling and maintained at Ajani, Nagpur Electric Loco Shed of central railway, has a history of frequent failure of middle axle primary inner suspension spring. The study of failures revealed that this specific component fails at a very high rate. The failure investigation starts the experimental spectroscopy analysis to find chemical composition for different failed specimens of springs, and it is observed that all parameters are within the recommended range. Also the stiffness of primary middle axle and end axle suspension springs has been checked on spring testing machine to measure deflection of spring, and it is as per recommended values. Further static stress analysis is carried out using analytical and finite element analysis for various phases of operation of rail vehicle like straight track, curved track and also for tractive effort. The static stress analysis has not revealed the cause of failure, and hence the dynamic analysis is performed. For dynamic analysis, dynamic model of suspension system is considered and analyzed using analytical method, finite element method and using MATLAB Simulink model. The vibration response of actual suspension system is also measured using FFT analyzer. It has been seen that the frequency of excitation and the natural frequency of the system are very close to each other which has resulted into suspension vibration amplitude of 6–8 mm. Fatigue analysis is carried out using finite element method to investigate the effect of dynamic loading on the failures of suspension spring. This analysis revealed that the middle axle inner suspension spring has finite life and due to which spring failure occurs earlier.

Classical, higher-order, zig-zag and variable kinematic shell elements for the analysis of composite multilayered structures

Abstract In the present work, a shell finite element with a variable kinematic field based on a new zig-zag power function is proposed for the analysis of laminated shell structures . The kinematic field is written by using an arbitrary number of continuous piecewise polynomial functions. The polynomial expansion order of a generic subdomain is a combination of zig-zag power functions depending on the shell thickness coordinate. As in the classical layer-wise approach, the shell thickness can be divided into a variable number of mathematical subdomains. The expansion order of each subdomain is an input parameter of the analysis. This feature enables the solution to be locally refined over generic regions of the shell thickness by enriching the kinematic field. The advanced finite shell elements with variable kinematics are formulated in the framework of the Carrera Unified Formulation. The finite element arrays are formulated in terms of fundamental nuclei, which are invariants of the theory approximation order and the modelling technique (Equivalent-Single-Layer, Layer-Wise). In this work, the attention is focused on linear static stress analyses of composite laminated shell structures. The governing equations are obtained by applying the Principle of Virtual Displacements, and they are solved using the Finite Element method . Furthermore, the Mixed Interpolated Tensorial Components (MITC) method is employed to contrast the shear locking phenomenon . Several numerical investigations are carried out to validate and demonstrate the accuracy and efficiency of the present shell element.

ESTIMATION OF STATIC COULOMB STRESS CHANGE AND STRONG MOTION SIMULATION FOR JIUZHAIGOU 7.0 EARTHQUAKE BASE ON SENTINEL-1 INSAR DATA INVERSION

Abstract. On August 8, 2017, an earthquake of M 7.0 occurred at Jiuzhaigou. Based on the Sentinel-1 satellite InSAR data, we obtained coseismic deformation field and inverted the source slip model. Results show that this event is dominated by strike slip, and the total released seismic moment is 8.06 × 1018 Nm, equivalent to an earthquake of Mw ~ 6.57. We calculated static stress changes along strike and dip direction, and the static stress analysis show that the average stress drop are at low level, which may be responsible for the low level of ground motion during Jiuzhaigou earthquake. The coseismic Coulomb stress changes are calculated base on the inverted slip model, which revealed that 82.59 % of aftershocks are located in the Coulomb stress increasing area, 78.42 % of total aftershocks may be triggered by the mainshock aftershock, indicating that the mainshock has a significant triggering effect on the subsequent aftershocks. Based on stochastic finite fault model, we simulated regional peak ground acceleration (PGA), peak ground velocity (PGV) and the intensity, and results could capture basic features associated with the ground motion patterns. Moreover, the simulated results reflect the obvious rupture directivity effect.

Investigation on Static Stress Analysis of Portal Axle Gearbox

Investigation on Static Stress Analysis of Portal Axle Gearbox

Characteristics of Reduction Gear in Electric Agricultural Vehicle

In electric agricultural machine a reduction gear is needed to convert the high speed rotation motion generated by DC motor to lower speed rotation motion used by the vehicle. The reduction gear consists of several spur gears. Spur gears are the most easily visualized gears that transmit motion between two parallel shafts and easy to produce. The modelling and simulation of spur gears in DC motor reduction gear is important to predict the actual motion behaviour. A pair of spur gear tooth in action is generally subjected to two types of cyclic stress: contact stress and bending stress. The stress may not attain their maximum values at the same point of contact fatigue. These types of failure can be minimized by analysis of the problem during the design stage and creating proper tooth surface profile with proper manufacturing methods. To improve its life expectation in this study modal and stress analysis of reduction gear is simulated using ANSYS workbench based on finite element method (FEM). The modal analysis was done to understand reduction gear deformation behaviour when vibration occurs. FEM static stress analysis is also simulated on reduction gear to simulate the gear teeth bending stress and contact stress behaviour.

Shape Optimization of Orthopedic Fixation Plate Based on Static Stress Analysis

Excessive displacement of fracture blocks and stress shielding at fracture position are two important reasons of bone reduction malformation, secondary fracture in plate fixation. In order to improve biomechanical environment of bone after plate implanting, a novel method of shape optimization based on static analysis was proposed in this paper. Combined with clinical operation constraints, the plate geometry was automatically optimized based on the minimization principle of plate stress and block offset. Experimental results show that the proposed method not only can decrease the displacement of fractured femur and reduce the stress of fracture site, but can provide a good biomechanical environment for fracture treatment.

Static, Dynamic and Impact Stress Analysis of a Bus Body Structure Using Finite Element Analysis

Static, Dynamic and Impact Stress Analysis of a Bus Body Structure Using Finite Element Analysis

Stress Relaxation of a Sport Utility Vehicle Chassis Using a Dynamic Force Counteracting Approach

Structural failures in a Chinese sport utility vehicle (SUV) Land-wind X6 chassis were reported in recent years, thus, it is meaningful to conduct trouble-shooting and effective optimization to improve the chassis. Stress relaxation of the Land-wind X6 chassis using a novel dynamic force counteracting approach was carried out in this study. Finite Element Analysis (FEA) model of the chassis was firstly established and theoretical modal analysis was performed using the FEA model, experimental modal analysis was followed to validate the theoretical modal analysis and the FEA model. Further static and local stress analyses demonstrate that irrational designs between the longitudinal beams and the suspension components lead to inadequate stiffness and excessive stress concentrations which would cause fatigue and structural failure when the SUV chassis is subject to complex and severe excitations. A novel dynamic forces counteracting approach was introduced to optimize the chassis structure, FEA results show that excessive stress concentrations were obviously eliminated and the chassis stiffness, especially the torsional stiffness was greatly improved after optimization, followed industrial implementation also verifies that the FEA-based study and product optimization performed in this work are successful and significant.

Computed tomography based 3D modeling and analysis of human knee joint

This study aims at obtaining a patient specific 3D model of human knee joint from Computed tomography (CT) data via reverse engineering approach. CT scan data in Digital imaging and communications in medicine (DICOM) format was loaded into DeVide, medical image processing software to obtain 3D Computer aided design (CAD) model. The CAD model was saved in Stereolithography (STL)format, which was further processed in MeshLab and MagicsRP software to obtain error-free file. Static stress and deformation analysis at the joint was performed for Stainless steel (SS 316L) and CoCrMo alloy in ANSYS software. Anatomical model of the knee joint was fabricated on EOSINT P395 machine using PA2200 polyamide powder. Finite element analysis shows that CoCrMo alloy has lower deformation in comparison with stainless steel.

Static and Vibration Analysis of an Aluminium and Steel Bus Frame

The transport sector is increasing day by day to satisfy the global market requirement. The bus is still the main mode of intercity transportation in Canada. Despite, an essentially unchanged conception, the total weight of the bus has increased by over 25% during the last three decades. To solve this problem, industrialists have moved to the use of light metals in the transportation field. Therefore, use of lightweight materials, such as aluminum is essential to reduce the total weight of bus. In this study, the focus is on the bus frame as it represents 30% of the total weight and it is the most stressed part of the bus. Its life duration is more important compared to that of all other elements. Thus, a study of the static and vibratory behavior would be very decisive. In this article, two types of analysis are carried out. First is the modal analysis to determine the natural frequencies and the mode shapes using a developed dynamic model of the bus. Because if any of the excitation frequencies coincides with the natural frequencies of the bus frame, then resonance phenomenon occurs. This may lead to excessive deflection, high stress concentration, fatigue of the structure and vehicle discomfort. In this case, the results analysis shows that the natural frequencies are not affected by the change of material. The second type of analysis is the linear static stress analysis to consider the stress distribution and deformation frame pattern under static loads numerically. For the numerical method, the frame is designed using SolidWorks and the analysis is made using Ansys WorkBench. The maximum Von Mises stress obtained for the static loading is in the same order for the three chassis frames studied. But in the case of the aluminium frame, the weight of 764 kg was reduced.

Dynamics Modeling of a Wave Glider With Optimal Wing Structure

The wave glider is a new concept marine robot that can make use of wave energy to obtain thrust. Differ from the traditional unmanned vehicle, the wave glider consists of the floating body, the connecting tether, and the submerge glider. It can be regarded as a special catamaran structure. Therefore, the conventional kinetic models of the unmanned vehicle are inapplicable to the wave glider. In this paper, we propose a non-linear kinetic model of wave glider of six degrees of freedom based on three reference coordinate frames. The calculating formula between the vertical liquid velocity and the system advance speed is derived by using the kinetic model. A method to design a glider wing structure under fixed wave speed in vertical direction was also presented. On the basis of the static stress analysis of the Glider wings, we compare different factors influencing the advance speed and optimize them by comparing the simulation results with the calculation results.

Numerical Modelling of Mining-induced Inrushes from Subjacent Water Conducting Karst Collapse Columns in Northern China

Collapse columns are geological features formed by chimney caving of karst voids. Collapse columns can cut through the rock mass and introduce vast geological complexity in coalfields. When a collapse column becomes accessible to a confined aquifer, water inrush disasters can be triggered. In northern China, inrushes related to collapse columns occur in regions where extensive Ordovician limestone underlies the coal measures. This limestone is strongly karstified and holds large quantities of water. The piezometric surface can be considerably higher than the coal extraction level. Numerical simulation was used to explore how the water inrush pathway forms, based on a demonstration model. First, the evolution of the stress field, damage field, and flow volume within the coal floor was analysed. Then factors such as the column height, mechanical strength of the coal floor, and hydraulic pressure in the aquifer were considered. In the demonstration models, if the height of the collapse column exceeded 35 m and the initial thickness of the aquiclude was less than 15 m, an inrush definitely occurred, even when the strength of the floor strata was relatively high. Finally, a practical case of water inrush in the Fangezhuang coal mine related to a collapse column was numerically investigated. Modelling of the fracturing process provided insight into evolution of the fracture zone and inrush processes that cannot be observed in the field and are difficult to evaluate using static stress analysis.

01.10: Different approaches towards numerical modelling of bolt bearing

ABSTRACTBolt bearing is characterized by large plastic deformations that occur mainly near the contact between bolts and plates and may possibly lead to fracture. Numerical modelling of such behaviour is not trivial. The paper focuses on the procedures for numerical analysis that allow numerical modelling of bolt bearing up to fracture. The commercially available software Abaqus software was used for this purpose, taking the advantages of built‐in material models and numerical procedures without introducing the user subroutines. The problem of bolt bearing is assessed using static stress analysis, explicit analysis and coupled Eulerian‐Lagrange analysis. The fracture model considered is based on stress modified fracture model and relies on the accumulating damage and on the reducing stiffness of finite elements to the point, where they offer no resistance and can be either removed from the model or are left with negligible stiffness. The required parameters (stress triaxiality, equivalent plastic strain to failure and displacement to failure) were determined from the experimental data.A few different bolted connections with different types of failure are analysed with full failure model and the results are compared with experiments. The advantage of Eulerian meshing is considered, where excessive plastic deformations lead to contact problems. Coupled Eulerian‐Lagrange analysis with model parts expected to have large deformations were modelled with Eulerian approach and the rest with more conventional Lagrange approach. Diverse material models, element options, time step and their impact on numerical simulation were compared and optimized for speed and accuracy.

Rock burst assessment and prediction by dynamic and static stress analysis based on micro-seismic monitoring

Rock burst assessment and prediction by dynamic and static stress analysis based on micro-seismic monitoring