Stress-strain Analysis Research Articles

Experimental and numerical investigation of electrochemical and tribological behavior of aluminum alloys

This paper has compared the electrochemical and tribological behavior of Aluminum-Lithium (Al-Cu-Li) alloys with conventional aluminum alloy. Potentiodynamic polarization test and Scanning Electron Microscopy (SEM) surface analysis were conducted. Results depicted that the 2060 alloy showed a 20% better polarization resistance and corrosion rate than the remaining alloys. Energy Dispersive Spectroscopy (EDS) analysis showed that the corroded surfaces were mostly composed of oxides and chlorides indicating mainly fretting corrosion and environmental-assisted corrosion in all tested alloys. Tribological behavior was evaluated using a ball-on-disk tribometer with load variation (3 N and 5 N). Conventional alloys showed better wear results with low values Coefficient of friction (COF) and almost 50% lesser wear rate than 2060 and 2195. Numerical Modelling based on corrosion results was conducted using Finite Element Analysis (FEA). The simulation of the plate (containing pitting, line cracks, and abrasive grooves) revealed that the abrasive grooves stand out to be the most intense stress risers than the rest within the corroded alloy. These stress risers are detrimental to the integrity of the aircraft. Furthermore, the comparative stress-strain analysis during simulation, showed that conventional alloy produced the highest strain under the same applied environment. There was more than 90% agreement in the experimental and simulated results.

A FEM Structural Analysis of a Francis Turbine Blade Parametrized Using Piecewise Bernstein Polynomials

Several methodologies have successfully described the runner blade shape as a set of discrete sections joining the hub and shroud, defined by 3D geometrical forms of considerable complexity. This task requires an appropriate parametric approach for its accurate reconstruction. Among them, piecewise Bernstein polynomials have been used to create parametrizations of twisted runner blades by extracting some cross-sectional hydrofoil profiles from reference CAD data to be approximated by such polynomials. Using the interpolating polynomial coefficients as parameters, more profiles are generated by Lagrangian techniques. The generated profiles are then stacked along the spanwise direction of the blade via transfinite interpolation to obtain a smooth and continuous representation of the reference blade. This versatile approach makes the description of a range of different blade shapes possible within the required accuracy and, furthermore, the design of new blade shapes. However, even though it is possible to redefine new blade shapes using the aforementioned parametrization, a remaining question is whether the parametrized blades are suitable as a replacement for the currently used ones. In order to assess the mechanical feasibility of the new shapes, several stages of analysis are required. In this paper, bearing in mind the standard hydraulic test conditions of the hydrofoil test case of the Norwegian Hydropower Center, we present a structural stress–strain analysis of the reparametrization of a Francis blade, thus showing its adequate computational performance in two model tests.

Bending behavior and bond analysis on adhesively bonded glulam-concrete panels fabricated with wet bonding technique

In this paper, we report on the effect of adhesive type on the bending behavior of adhesively bonded glulam-concrete composite panels. Steel-reinforced and unreinforced concrete were bonded to glued-laminated timber (GL-24 h) panels with polyurethane (PUR) and epoxy adhesives using the wet bonding technique. The PUR and epoxy adhesives (both were two-component adhesives) were selected to represent brittle and ductile adhesive behaviors. Four-point bending load was applied to glulam-concrete composite panels to investigate their bending behavior. The bending behavior measured includes bending load vs. mid-span deflection, strain distribution at the mid-span of the panel, and strain distribution between the loading point and its adjacent support. These were determined by linear variable differential transformers (LVDTs), strain gauges, and digital image correlation (DIC) technique. The experimental results showed that polyurethane-bonded glulam-unreinforced concrete panels showed similar load vs. mid-span deflection curves to epoxy-bonded glulam-unreinforced concrete panels and epoxy-bonded glulam-reinforced concrete panels. The shear stress, shear deformation, and peel strain analyses at the adhesive bond line showed that debonding at the glulam-concrete interface was more likely to occur for panels bonded with the ductile polyurethane.

Material Characterization Based on a Comparative Analysis of Various Metals Elongations

Abstract: In this work, characterization procedures for examining materials and environmental factors are implemented utilizing strain gauges and DHT11 sensors. Stress-strain and fatigue analysis was made possible by the use of strain gauges to monitor the deformation and strain in various materials. By using the DHT11 sensors to detect temperature and humidity, environmental conditions might be analyzed. The sensor measurements were recorded and interpreted using data logging and visualization tools, and the noise and signal were improved using signal processing techniques. Correlation analysis was also performed to look into connections between the measured variables. The application showed the ability to learn important lessons about how things behave under pressure and in different environments.

Predict the fatigue unloading elastic-plastic reduction mechanism of single crystal 3C-SiC Newton layer by reconstructed multi-dimensional dynamic static combination indenter

To explore the elasto-plastic reduction mechanism of single crystal 3C-SiC Newton layer under fatigue unloading. Reconstructed multi-dimensional single crystal 3C-SiC Newton layer unloading dynamic - static combined head. The evolution law of dislocation loop, the trend of load displacement and the direction of strain concentration expansion during fatigue unloading are analyzed. According to the stress characteristics of nanoindentation process and the requirements of real indentation environment, the NVE ensemble matrix and boundary condition parameters are integrated and optimized. The influence of indenter shape on the evolution process of dislocation ring emergence, fracture and connection and the evolution mechanism are analyzed. Through diamond identification method and stress-strain analysis method, the multi-dimensional force analysis of plastic unloading of nano-indentation is realized. It is found that the yield limit of semi-circular indenter first reaches the yield limit from the elastoplastic loading stage to the plastic loading stage than the normal four-cone. Combined with the load displacement curve, the real stress characteristics of the nano-indentation single crystal 3C-SiC Newton layer are analyzed. The results show that elastoplastic reduction existed in fatigue unloading, and the generation and development of micro-dislocation rings in elastoplastic deformation reduction under fatigue unloading of different dimensions indenter are different. The ultimate yield stress of semi-circular indenter is 3.82GPa and the ultimate strain is 1 %，the ultimate yield stress of positive quad conical indenter is 6.60GPa and the ultimate strain is 1.5 %. The elasto-plastic reduction mechanism of fatigue unloading is directly driven by the plastic evolution mechanism of dislocation ring.

Revealing and simulating the effect of hidden damage on local and full-field deformation behaviour of cast aluminium

Pores have been the main focus of quality assurance in castings. Latest research has shown that in aluminium castings pores can form only if there is existing entrainment damage, i.e., pores are merely the visible parts of the entrainment damage, and usually invisible damage is much more extensive. However, its effect on deformation behaviour has not been previously established or observed in-situ. This work applies 2D Digital Image Correlation (DIC) to an in-situ full-field stress-strain analysis of tensile samples with a non-conventional heterogeneous stress distribution. The observations reveal that the effect of hidden damage extends far beyond its impact on fracture behaviour and is responsible for initiating local strain concentrations during deformation. By extracting local stress-strain data, FE simulations have been performed to mimic the effect of local hidden damage on the heterogeneous stress-strain field. SEM and FIB-SEM analysis has been applied to investigate the cause for the strain concentrations. The combined results show that hidden damage in the form of oxide films is not only responsible for premature fracture, but also affects the deformation behaviour of tensile samples by introducing dispersed strain concentrations.

SIMPLIFIED MECHANISTIC – EMPIRICAL ANALYSIS OF FLEXIBLE PAVEMENT

Pavement stress-strain analysis is an ideal tool for analytical modelling of pavement behaviour and thus, constitutes an integral part of pavement design and performance evaluation. It is the fundamental basis for the mechanistic design theory. Predicting pavement response by simplified procedure analysis by relying on equivalency factors using axle load spectrum which is obtained from Weigh-In-Motion (WIM) data is aimed for this study. The framework for computing the structural response of the standard axle group loads on a pavement structure by using a layered elastic computer program and calculation of pavement responses for axle load distribution for different axle groups and axle types by using the theoretical analysis. From the study, the summary of the obtained results are as follows: (1) axle load distribution was developed for the four considered axle configurations; (2) Single axle with single tyre has the greatest destructive impact followed by the tridem axle with dual tyres (TRDT) and next by TADT. The least destructive axle group type is the Single Axle with Dual tyre SADT.The predicted pavement response by theoretical analysis indicates that the critical tensile strains obtained results are all greater than the critical vertical strains. At the heaviest axle load, from 70KN, for both SAST and SADT; from 140KN for TADT; and from 210KN, the critical strains have the greatest magnitude by SAST and followed by SADT and next by TADT. The least critical tensile strain is from the TRDT.

Homogenization and numerical algorithms for two-scale modeling of porous media with self-contact in micropores

The paper presents two-scale numerical algorithms for stress–strain analysis of porous media featured by self-contact at pore level. The porosity is constituted as a periodic lattice generated by a representative cell consisting of elastic skeleton and a void pore. Unilateral frictionless contact is considered between opposing surfaces of the pore. For the homogenized model derived in our previous work, we justify incremental formulations and propose several variants of two-scale algorithms which commute iteratively solving of the micro- and the macro-level contact subproblems. A dual formulation which takes advantage of the assumed microstructure periodicity and a small deformation framework, is derived for the contact problems at the micro-level. This enables to apply the semi-smooth Newton method. For the global, macrolevel step two alternatives are tested; one relying on a frozen contact identified at the microlevel, the other based on a reduced contact associated with boundaries of contact sets. Numerical examples of 2D deforming structures are presented as a proof of the concept.

By Visualizing the Deformation with Mechanoluminescent Particles, Additive Manufacturing Offers a Practical Alternative to Stress and Strain Simulation

The use of stress–strain analysis in structural design or mechanical components is critical for avoiding or investigating structural failures. In the case of complicated designs, mathematical full-field stress modeling produces imprecise predictions. Experimental analysis can be used as a replacement for mathematical modeling, but with the use of currently available strain gauges, it is cumbersome and impossible in the case of moving parts. Mechanoluminescent materials transform mechanical energy into visible light and can be used as a replacement for strain gauges to monitor strain/stress. Three-dimensional printing technology has made major advances in terms of additive manufacturing. In this article, we describe a method to produce an ML 3D print. The fabricated samples are precise and versatile and satisfy the need for easy and non-destructible spatial stress analysis. A 3D printed photopolymer sample with SrAl2O4: Eu, Dy particle addition only to the final layers was tested, and the number of layers was optimized. It was determined that the optimal number of layers for easy detection is in the range of 10 to 20 layers. It opens the possibility for the real-time evaluation of complex uneven forces on complex parts, thus having a good potential for commercialization.

Design and Development of a Multifunctional Convertible Wheelchair in a Low-Income Country Context

The objective of this study is to design and develop a mobility aid that performs three different functions to serve patients with a cost-effective space utilizing a wheelchair. The focus was to develop an affordable product considering the poor economic status of the targeted users. A convertible multifunctional wheelchair was developed that can be used as a stretcher and as a regular wheelchair, and it has a pair of crutches to assist in walking. The design and stress-strain analysis of the product was done using SolidWorks 2019. Then, the product was manufactured using the simplest available manufacturing tools and materials. It was possible to fabricate a prototype of this multifunctional at a very cheap cost of BDT 14,250 ($162 approximately). However, it is believed that in mass production, the unit cost can be reduced by 40-50%. The fabricated prototype was lightweight with an average weight of approximately 16 kg allowing it to be portable. The design specifications also ensure ergonomic comfort. It can be contended that this device can be a cost-effective solution for patients and public hospitals in Bangladesh and similar low-income countries.

High performance modeling of the stress-strain state of thin-walled shell structures with the use of deep learning

Computer modeling is one of the most common approaches to the analysis of thin-walled shell structures stress-strain state analysis. It requires considerable time costs and high-performance hardware, especially when it is necessary to conduct a comparative analysis of various shell configurations. In this paper, we propose the use of deep learning methods to improve performance of this process. The purpose of work is to develop methods for high-performance computer simulation of thin-walled shell structures using deep neural networks, allowing to take into account geometric and physical properties of the structure as well as the load applied to it. A training approach and deep neural network architecture were developed to perform computer modeling of the stress-strain state of the shell. To form a training dataset, a computational experiment was carried out to simulate 3904 different configurations of doubly curved shallow shells that differ in linear dimensions, curvature radii, and materials used. Based on this dataset, 30 deep neural networks with different architectures were trained. To determine the optimal architecture in terms of modeling accuracy, mean absolute percentage error with clipping near-zero samples was calculated for each of the neural networks based on the test dataset. A network has been developed that allows calculating the stress-strain state of different shell configurations under an arbitrary uniformly distributed load. This is the first solution in the field of shell neural network modeling that allows us to vary the applied load, geometric and physical parameters of the shell and obtain calculation results at an arbitrary point of its middle surface. Performance measurements were carried out which show that the developed neural network allows simulating the stress-strain state of a shell structure 2117 times faster compared to the duration of solving the same problem by classical simulation. The modeling error using the network is at an acceptable level. An original architecture of a neural network for modeling the stress-strain state of shells was proposed which, through minor modifications, can be adapted for high-performance modeling of other building structure types. In accordance with the described architecture, a deep neural network was trained which reduces the computation time by several orders of magnitude. The results obtained are of high practical importance for researchers in the field of thin-walled shells modeling since they allow us to significantly reduce the time costs associated with conducting computational experiments. One of the possible applications for developed solution is prototyping of various shell configurations. Once prototyping is complete, the most efficient shell configurations can be explored in detail using classical computer simulation techniques.

Numerical Simulation of the Welding Process during the Main Circulation Pump Impeller Repair

Paper presents a numerical simulation of the main circulation pump impeller damaged parts repair/replacement welding process, for the prediction of welding-induced residual stresses. 3D numerical model creation of the impeller flange and central hub welded joints. Thermal and stress-strain analysis of assessed parts using the finite element method. Calculation of equivalent residual stresses in the area of examined welded joints. Applicability of results in further impeller integrity analyzes. The results confirmed the suitability of the chosen welding procedure and technology.

Analysis of the Influence of Thermal Loading on the Behaviour of the Earth’s Crust

The article focuses on the deformation and strain-stress analysis of the Earth’s crust under external thermal loading. More specifically, the influence of cyclic changes in the surface temperature field on the stress and displacement inside the crust over a two-year time span is investigated. The finite element program MSC.Marc Mentat was used to calculate the stresses and displacements. For practical analysis reasons, the Earth’s crust is simplified as a planar, piecewise homogeneous, isotropic model (plane strain), and time-varying temperature functions of illumination (thermal radiation) from the Sun are considered in the local isotropy sections of the model. Interaction between the Earth’s crust and mantle is defined by the Winkler elastic foundation. By applying a probabilistic approach (Monte Carlo Method), a new stochastic model of displacements and stresses and new information on crustal displacements relative to the Earth’s mantle were obtained. The results proved the heating influence of the Sun on the Earth’s crust and plate tectonics.

Experimental Study on Small-Strain Elastic Parameters of Biochar–Methanotroph–Clay Mixture

During the service of a landfill, uneven soil settlement and earthquakes can cause changes to the pore structure and cracks in the covering layer. The use of a biochar–methanotroph–clay mixture as a new landfill covering layer, can improve its engineering properties. The biochar–methanotroph–clay mixture’s shear-wave velocity and compression-wave velocity were measured by the bender–extender element test, and the elastic parameters under small-strain conditions, such as maximum shear modulus, Gmax, maximum constrained modulus, Mmax, and Poisson’s ratio, ν, were obtained. The parameters showed that the elastic characteristics and lateral deformation capacity were of great significance for settlement, seismic field, and stress–strain analysis. Based on the bender–extender element test, the effects of different compaction degrees, and biochar content on Gmax, Mmax, and ν of the biochar–clay mixture, and different methane cultivation days on the biochar–methanotroph–clay mixture, were investigated. The results showed that the Gmax, Mmax, and ν of the biochar–clay mixture increased with the increase in biochar content and dry density. When the biochar content was 15%, and the dry density was 1.64 g/cm3, the ν increased significantly. The Gmax and Mmax of the biochar–methanotroph–clay mixture tended to increase with the increase in methane cultivation days, and the higher the biochar content, the more obvious the increasing trend. The ν showed a decreasing trend with the increase in methane cultivation days, and the resistance to lateral deformation was stronger.

Lower Wishbone Modeling and Analysis for Commercial Vehicle Independent Suspension System

The primary goal of this paper is to design and analyse the entire double wishbone suspension system for a commercial vehicle in order to improve the vehicle’s stability and handling. The suspension system has seen tremendous advancement. A commercial vehicle’s suspension system must be long-lasting, light in weight, efficient, and cost-effective. The vehicle must be able to withstand the harsh off-road terrain environment. As a result, it is critical to concentrate on the stress strain analysis study of the lower wishbone arm in order to improve and modify the existing design.

Assessment of the effect of topological optimization of metal parts

Purpose. The purpose of this article is to evaluate the efficiency of using the “Shape optimization” option in the Fusion 360 software product of the American company Autodesk for the details of the braking system of a mining electric locomotive. Methodology. With the advent of modern computer programs, the content of the design engineer’s work has changed, the design process has been reduced to the development of a 3D model of a metal product, which can then be subject to stress-strain analysis and, based on the results of this analysis, low-stress areas of the product which can be removed are be determined, that is, the weight of the metal used is reduced. Of particular importance is generative design, which is a new design technology. It is based on the use of software that can independently generate three-dimensional models that meet specified conditions without the involvement of a designer. Essentially, in the “human-machine” system, creative functions are passed to the computer, which deals well with them. The second most important technology is topological optimization (Shape optimization), which is applied to a model already developed by the designer in order to improve it. Findings. The paper presents the results of the research on reducing the weight of the parts of the braking system of the mine electric locomotive due to the topological optimization of their structures in the Fusion 360 software product. The removal of unloaded areas of the product was performed using the special option “Shape optimization” of this program.The effect of weight reduction in products after topological optimization is estimated to be approximately 35-45%. Originality. The use of topological optimization in the details of the braking system of the mining electric locomotive is a new approach to optimizing the structure and obtaining parts of reduced mass. Practicalvalue. The application of topological optimization at the design stage helps to find a construction design option with the most rational distribution of material and voids in a given area taking into account strength and stiffness, and, thus, significantly reduce its weight.

Development of Fragility Functions for Embankment Slopes on Liquefiable Soils

In seismically active regions, high-filled embankment slopes on liquefiable soils tend to damage after strong earthquakes. Therefore, post-seismic damages should be estimated as soon as possible to mitigate potential losses. Fragility function is an efficient tool for assessing the seismic vulnerability conditions of structures, which links the probability of exceeding different limit states to seismic intensity. An embankment slope on liquefiable soils at Yading Airport in China was selected as the study object, and a series of numerical analyses of the embankment-foundation system utilizing the finite element method were conducted. Advanced dynamic constitutive models considering liquefaction and hysteresis characteristics were also adopted to simulate the nonlinear stress–strain behavior of soils under cyclic loadings. The post-seismic stability of embankment slopes was assessed using the strength reduction method (SRM) based on the stress–strain analysis. On this basis, the permanent ground deformation (PGD) at the ground-free field conditions was selected as the intensity measure (IM), while the factor of safety (FoS) of the slopes was selected as the damage measure (DM). Then, a procedure was presented for deriving seismic fragility functions with different damage states in light of incremental dynamic analysis (IDA). This paper aims to investigate the effects of different embankment typologies, such as the thickness of liquefiable soils and slope inclination, on the post-seismic vulnerability of embankment slopes. The fragility curves constructed in this study may soon be helpful for predicting the post-seismic damage of similar high-filled embankment slopes on liquefiable soils, which enables efficient traffic control and rapid disaster response.

Stress-Strain State Analyses of the Composite Steel and Concrete Grid Structure

The study provides developing a method of the tress-strain state analyses of the composite steel and concrete grid structure, the main assumptions, and analysis of the geometry of the structure, the elementary states of equilibrium of the structures are considered, and the systems of determining equations are solved. The method of the stress-strain state analyses is proposed to be performed using the basic provisions of the technical theory of calculating thin shells. The method provides obtaining and solving the design models, and the equations needed for calculating the bearing capacity of the members of the composite steel and concrete grid structure. In particular, the method is for determining the essential area of the cross-section of the prestressed reinforcement, as well as to determine the forces that are acted in the composite steel and concrete structure. In general, the method provides designing the composite steel and concrete structure, determining the bearing capacity, and selecting the necessary dimensions of the structural elements of the composite steel and concrete structure.

Use of Geosynthetic in Soft Soil Foundation in Mining Area: A Case Study with Analytical and Numerical Studies

The design of embankments on soft foundations with the application of geosynthetics is a subject frequently studied. In addition, the disposal of mine waste material is a needed challenge, due to area availability. In this context, this work presents a study case of application of geosynthetics for soft foundations treatment, to make feasible the construction of a mine waste pile embankment. The study also presents a stress–strain analysis via finite-element modeling considering a critical state soil mechanics approach. Then, a geosynthetic liner and internal drainage system design is presented based on the results of this analysis. Hence, this liner and internal drainage are required due to the environmental concerns of the waste material. Thus, a discussion on the use of critical state soil mechanics and the stress–strain finite-element method to assess the need for treatment on foundation for embankments construction in soft material is presented. The deformations assessed at the stress–strain study showed that the waste material would absorb the foundation strains with only controlling the rising ratio. Thus, the solution proposed with the numerical analysis reduces the reinforcement that would be proposed usually. Furthermore, the ease installation process and the large strains capabilities made possible an embankment construction on soft soil near to a mine industrial plant.

Evaluation of Powder Metallurgy Workpiece Prepared by Equal Channel Angular Rolling.

The aim of the article is to examine the workability of sintered powder material of aluminum alloy (Alumix 321) through severe plastic deformations under the conditions of the equal channel angular rolling (ECAR) process. Accordingly, the stress-strain analysis of the ECAR was carried out through a computer simulation using the finite element method (FEM) by Deform 3D software. Additionally, the formability of the ALUMIX 321 was investigated using the diametrical compression (DC) test, which was measured and analyzed by digital image correlation and finite element simulation. The relationship between failure mode and stress state in the ECAR process and the DC test was quantified using stress triaxiality and Lode angle parameter. It is concluded that the sintered powder material during the ECAR processing failure by a shearing fracture because in the fracture location the stress conditions were close to the pure shear (η and θ¯ ≈ 0). Moreover, the DC test revealed the potential role as the method of calibration of the fracture locus for stress conditions between the pure shear and the axial symmetry compression.