A novel formulation of material nonlinear analysis in structural mechanics

This article demonstrates a novel approach for material nonlinear analysis.This analysis procedure eliminates tedious and lengthy step by step incremental and then iterative procedure adopted classically and gives direct results in the linear as well as in nonlinear range of the material behavior.Use of elastic moduli is eliminated.Instead,stress and strain functions are used as the material input in the analysis procedure.These stress and strain functions are directly derived from the stress-strain behavior of the material by the method of curve fitting.This way,the whole stress-strain diagram is utilized in the analysis which naturally exposes the response of structure when loading is in nonlinear range of the material behavior.It is found that it is an excellent computational procedure adopted so far for material nonlinear analysis which gives very accurate results,easy to adopt and simple in calculations.The method eliminates all types of linearity assumptions in basic derivations of equations and hence,eliminates all types of possibility of errors in the analysis procedure as well.As it is required to know stress distribution in the structural body by proper modelling and structural idealization,the proposed analysis approach can be regarded as stress-based analysis procedure.Basic problems such as uniaxial problem,beam bending,and torsion problems are solved.It is found that approach is very suitable for solving the problems of fracture mechanics.Energy release rate for plate with center crack and double cantilever beam specimen is also evaluated.The approach solves the fracture problem with relative ease in strength of material style calculations.For all problems,results are compared with the classical displacement-based liner theory.

Smart Dynamic Trafc Monitoring and Enforcement Syste

Enforcement of trafc rules and regulations involves a wide range of complex tasks,many of which demand the use of modern technologies.variable speed limits(VSL)control is to change the current speed limit according to the current trafc situation based on the observed trafc conditions.The aim of this study is to provide a simulation-based methodological framework to evaluate(VSL)as an effective Intelligent Transportation System(ITS)enforcement system.The focus of the study is on measuring the effectiveness of the dynamic trafc control strategy on trafc performance and safety considering various performance indicators such as total travel time,average delay,and average number of stops.United Arab Emirates(UAE)was selected as a case study to evaluate the effectiveness of this strategy.A micro simulation software package VISSIM with add-on module VisVAP is used to evaluate the impacts of VSL.It has been observed that VSL control strategy reduced the average delay time per vehicle to around 7%,travel time by 3.2%,and number of stops by 48.5%.Dynamic trafc control strategies also alleviated congestion by increasing the capacity of the bottleneck section and improving safety.Results of this study would act as a guidance for engineers and decision makers to new trafc control system implementation.

Piezoelectric Vibration Harvesters Based on Vibrations of Cantilevered Bimorphs: A Review

With the advancement in the technologies around the world over the past few years, the microelectromechanical systems (MEMS) have gained much attention in harvesting the energy for wireless, self-powered and MEMS devices. In the present era, many devices are available for energy harnessing such as electromagnetic, electrostatic and piezoelectric generator and these devices are designed based on its ability to capture the different form of environment energy such as solar energy, wind energy, thermal energy and convert it into the useful energy form. Out of these devices, the use of a piezoelectric generator for energy harvesting is very attractive for MEMS applications. There are various sources of harvestable energy including waste heat, solar energy, wind energy, energy in floating water and mechanical vibrations which are used by the researchers for energy harvesting purposes. This paper reviews the state-of-the-art in harvesting mechanical vibrations as an energy source by various generators (such as electromagnetic, electrostatic and piezoelectric generators). Also, the design and characteristics of piezoelectric generators, using vibrations of cantilevered bimorphs, for MEMS have also been reviewed here. Electromagnetic, electrostatic and piezoelectric generators presented in the literature are reviewed by taking into an account the power output, frequency, acceleration, dimension and application of each generator and the coupling factor of each transduction mechanism has also been discussed for all the devices.

Scanning Electron Micrographic Investigation of Explanted (Used) Metallic Biomedical Implants for Corrosion and Other Mechanical Damage Responsible for Failure

This paper deals with detailed corrosion analysis of explanted devices. The study of total 6 different types of orthopedic metallic implant was carried out after collecting the clinical report from the doctors, who performed these implantations. The clinical report covered the purpose of implantation, body part where implantation was done, and physiological reasons of removal of implant. The metallurgical investigation to study corrosion and any other mechanical damage to the implant surface during their service period was done using the Scanning Electron Micrography. SEM presented in this paper reveals the presence of in-vitro corrosion and mechanical damage as well, which are corroborating well with clinical reports.

A novel stress-based formulation of finite element analysis

This paper demonstrates a novel formulation of structural analysis.A novel stress-based formulation of structural analysis for material nonlinear problems was proposed in earlier work.In this paper,this methodology is further extended for 3 D finite element analysis.The approach avoids use of elastic moduli as the material input in the analysis procedure.It utilizes the whole stress-strain curve of the material.It can be shown that this analysis procedure solved the nonlinear or plasticity problem with relative ease.This paper solves a uniaxial bar,in which the results are compared with the solutions of Green-Lagrange strain and Piola-Kirchhoff stresses.The uniaxial bar is also solved by a regression model in the‘scikit-learn’module in Python.The second problem solved is of a beam in pure bending for which the energy release rate is measured.For the beam in pure bending,the bending moment carrying capacity of the beam section is evaluated by this methodology as the crack propagates through the depth of the beam.It can be shown that the methodology is very simple,accurate,and clear in its physical steps.