Using Nonlinearities for Improved Stress Analysis by Thermoelastic Techniques

1997 ◽  
Vol 50 (9) ◽  
pp. 499-513 ◽  
Author(s):  
S. A. Dunn
Keyword(s):  
Stress Analysis ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
The Body ◽  
Analysis Techniques ◽  
Measuring Devices ◽  
Stress Changes ◽  
Infra Red ◽  
Strain Components ◽  
Potential Applications

Stress analysis by thermoelastic techniques has become a growing field since the application of sensitive infra-red measuring devices in the late 1960s. It is commonly asserted that by observing the variation in temperature on the surface of a body as the body undergoes a change in stress, the surface stress changes may be determined via a simple linear relation between temperature and stress. In making this assertion, two fundamental approximations are made: i) the stress changes in such a manner that adiabatic conditions are attained; and, ii) the material properties which relate the change in temperature to the change in stress remain constant throughout the loading process and are not significantly affected by either the stress or temperature change. The aim of this review article is to show the potential applications that can arise when the above two assumptions are not made. It will be shown that in many situations, these effects can significantly bias the experimental data. At first glance, such a bias can pose difficulties in the quantitative assessment of the data; if, however, the nature of these effects are understood sufficiently to be modeled mathematically, then important information can be gained which leads to a more powerful tool for stress analysis. If the assumption of adiabaticity is not applied, then the thermoelastic heat generation and conduction process which occurs when a composite laminate is stressed can be modeled. It will be shown how by observing the manner in which the surface generated temperature is biased by heat conducted from subsurface plies, that the strain components may be determined, even though such stress analysis techniques are typically assumed to measure only bulk stresses. Also, if the material properties are not assumed to remain constant with stress, it can be shown how an understanding of the variation in coefficient of thermal expansion with stress can lead to the potential for measuring residual stresses and plastic zones by thermoelastic techniques. This article contains 53 references.

A Review of Cord-Rubber Elastic Characteristics

1964 ◽  
Vol 37 (5) ◽  
pp. 1365-1390 ◽  
Author(s):  
Samuel K. Clark
Keyword(s):  
Stress Analysis ◽  
Internal Stress ◽  
Elastic Properties ◽  
The Body ◽  
Complex Nature ◽  
Pneumatic Tire ◽  
Analysis Techniques ◽  
Structural Applications ◽  
Elastic Characteristics ◽  
Reinforced Materials

Abstract The increased use of cord- and filament-reinforced materials in structural applications during the last few years has resulted in a greater interest in their elastic properties. In part the reason for this may be found by considering the basic nature of redundant structures, in which the loads carried by individual cords are determined to some extent by the elastic characteristics of the entire system. In such situations, a knowledge of elastic characteristics becomes important to structural design practice. As a second reason for increased attention to the elastic properties of such materials, one might cite the body of work which is now developing in the general area of filamentary reinforcement of materials. A knowledge of elastic characteristics is important in obtaining optimum reinforcement properties, and such studies inevitably lead to a clearer understanding of the internal stress-states of all reinforced materials. One result of all this activity is that much of the work done in the areas of fiberglass and whisker reinforcement increases the general understanding, in a broad way, of the action of cord-reinforced rubber since in many respects the problems are similar, although major differences do exist in the structure of the reinforcement itself. The elastic properties of cord-rubber materials are understood today much better than they were even ten or fifteen years ago. A great deal of this development has paralleled, and is well represented by, internal stress analysis techniques developed for what is perhaps the primary utilization of cord-reinforced rubber, namely, the pneumatic tire. In the case of the pneumatic tire, these stress analysis techniques have essentially followed three distinct phases. In the first, the anisotropic nature of such materials was completely ignored and loads and stresses were determined on the basis of assuming the materials to be isotropic or unreinforced. In the case of shell structures, this is the equivalent of calculating the statically determinate membrane stresses. In some cases such information was valuable and in a few instances it comprised a major portion of the effects being studied so that some reliance could be placed on such an analysis. However, in general, due to the complex nature of such reinforced materials, little faith can be given to analyses based on isotropic conditions.

Stress Analysis of Tire Sections

1996 ◽  
Vol 24 (4) ◽  
pp. 349-366 ◽  
Author(s):  
T-M. Wang ◽  
I. M. Daniel ◽  
K. Huang
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Stress Analysis ◽  
Strain Analysis ◽  
Experimental Stress ◽  
Inflation Pressure ◽  
Substantial Agreement ◽  
Finite Element Stress Analysis ◽  
Strain Components ◽  
Fringe Patterns

Abstract An experimental stress-strain analysis by means of the Moiré method was conducted in the area of the tread and belt regions of tire sections. A special loading fixture was designed to support the tire section and load it in a manner simulating service loading and allowing for Moiré measurements. The specimen was loaded by imposing a uniform fixed deflection on the tread surface and increasing the internal pressure in steps. Moiré fringe patterns were recorded and analyzed to obtain strain components at various locations of interest. Maximum strains in the range of 1–7% were determined for an effective inflation pressure of 690 kPa (100 psi). These results were in substantial agreement with results obtained by a finite element stress analysis.

scholarly journals Nanocomposite scaffolds for accelerating chronic wound healing by enhancing angiogenesis

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Hamed Nosrati ◽  
Reza Aramideh Khouy ◽  
Ali Nosrati ◽  
Mohammad Khodaei ◽  
Mehdi Banitalebi-Dehkordi ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Wound Healing ◽  
Tissue Regeneration ◽  
Molecular Mechanisms ◽  
Healing Process ◽  
The Body ◽  
Key Factors ◽  
Potential Applications ◽  
Nanocomposite Scaffolds

AbstractSkin is the body’s first barrier against external pathogens that maintains the homeostasis of the body. Any serious damage to the skin could have an impact on human health and quality of life. Tissue engineering aims to improve the quality of damaged tissue regeneration. One of the most effective treatments for skin tissue regeneration is to improve angiogenesis during the healing period. Over the last decade, there has been an impressive growth of new potential applications for nanobiomaterials in tissue engineering. Various approaches have been developed to improve the rate and quality of the healing process using angiogenic nanomaterials. In this review, we focused on molecular mechanisms and key factors in angiogenesis, the role of nanobiomaterials in angiogenesis, and scaffold-based tissue engineering approaches for accelerated wound healing based on improved angiogenesis.

Study on Thermal Analysis of the Shape of Improved Electric Cooker Liner Based on ANSYS Workbench

2014 ◽  
Vol 487 ◽  
pp. 568-571
Author(s):  
Yan Li Su ◽  
Lei Li ◽  
Wei Guo Han
Keyword(s):  
Thermal Analysis ◽  
Thermal Stress ◽  
Stress Analysis ◽  
Thermal Effects ◽  
The Body ◽  
Total Deformation ◽  
Ansys Workbench

In this paper, a comparative thermal analysis is carried out according to the bottom of HR-FD51 electric cooker liner about a large or small fillet. And then the thermal analysis results are applied to stress analysis as the body loads. The results show that it can reduce thermal stress and total deformation with a large fillet, thereby, improves the lifespan of electric cooker liner and thermal effects as well.

scholarly journals Mechanics of the small punch test: a review and qualification of additive manufacturing materials

2021 ◽  
Vol 56 (18) ◽  
pp. 10707-10744
Author(s):  
Jonathan Torres ◽  
Ali P. Gordon
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Materials Science ◽  
Contemporary Literature ◽  
The Body ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test ◽  
Testing Data ◽  
The Relationship

AbstractThe small punch test (SPT) was developed for situations where source material is scarce, costly or otherwise difficult to acquire, and has been used for assessing components with variable, location-dependent material properties. Although lacking standardization, the SPT has been employed to assess material properties and verified using traditional testing. Several methods exist for equating SPT results with traditional stress–strain data. There are, however, areas of weakness, such as fracture and fatigue approaches. This document outlines the history and methodologies of SPT, reviewing the body of contemporary literature and presenting relevant findings and formulations for correlating SPT results with conventional tests. Analysis of literature is extended to evaluating the suitability of the SPT for use with additively manufactured (AM) materials. The suitability of this approach is shown through a parametric study using an approximation of the SPT via FEA, varying material properties as would be seen with varying AM process parameters. Equations describing the relationship between SPT results and conventional testing data are presented. Correlation constants dictating these relationships are determined using an accumulation of data from the literature reviewed here, along with novel experimental data. This includes AM materials to assess the fit of these and provide context for a wider view of the methodology and its interest to materials science and additive manufacturing. A case is made for the continued development of the small punch test, identifying strengths and knowledge gaps, showing need for standardization of this simple yet highly versatile method for expediting studies of material properties and optimization.

scholarly journals Electrodermal Response in Gaming

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
J. Christopher Westland
Keyword(s):  
Computer Games ◽  
Emotional Response ◽  
Human Subjects ◽  
Skin Resistance ◽  
The Body ◽  
Electrodermal Response ◽  
Factors Affecting ◽  
Measuring Devices ◽  
History Of ◽  
Body Resistance

Steady improvements in technologies that measure human emotional response offer new possibilities for making computer games more immersive. This paper reviews the history of designs a particular branch of affective technologies that acquire electrodermal response readings from human subjects. Electrodermal response meters have gone through continual improvements to better measure these nervous responses, but still fall short of the capabilities of today's technology. Electrodermal response traditionally have been labor intensive. Protocols and transcription of subject responses were recorded on separate documents, forcing constant shifts of attention between scripts, electrodermal measuring devices and of observations and subject responses. These problems can be resolved by collecting more information and integrating it in a computer interface that is, by adding relevant sensors in addition to the basic electrodermal resistance reading to untangle (1) body resistance; (2) skin resistance; (3) grip movements; other (4) factors affecting the neural processing for regulation of the body. A device that solves these problems is presented and discussed. It is argued that the electrodermal response datastreams can be enriched through the use of added sensors and a digital acquisition and processing of information, which should further experimentation and use of the technology.

Thermal Stress in Teeth

1978 ◽  
Vol 57 (4) ◽  
pp. 571-582 ◽  
Author(s):  
B.A. Lloyd ◽  
M.B. McGinley ◽  
W.S. Brown
Keyword(s):  
Thermal Stress ◽  
Numerical Analysis ◽  
Material Properties ◽  
Thermal Stresses ◽  
In Vivo Studies ◽  
Tooth Structure ◽  
Analysis Techniques ◽  
Tooth Type

Observations of crack damage in the tooth structure from in vivo studies and in vitro experimental thermal cycling studies were combined with numerical analysis techniques to identify and isolate the influence of thermal stresses an the creation and propagation of cracks in teeth. The factors considered in this study included: (a) variations in tooth type or geometry (molar, bicuspid, etc.), (b) tooth age, (c) material properties of the tooth, (d) the magnitude of the change in the temperature of the environment surrounding the tooth, and (e) the thermal resistance between the tooth and the medium surrounding the tooth.

Warpage Simulation During Fan-Out Wafer-Level Packaging Process with Uncertainty of Material Properties

2021 ◽  
Vol 21 (5) ◽  
pp. 2987-2991
Author(s):  
Geumtaek Kim ◽  
Daeil Kwon
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Input Output ◽  
Wafer Level ◽  
High Input ◽  
Element Analysis ◽  
Packaging Process ◽  
Wafer Level Packaging

Along with the reduction in semiconductor chip size and enhanced performance of electronic devices, high input/output density is a desired factor in the electronics industry. To satisfy the high input/output density, fan-out wafer-level packaging has attracted significant attention. While fan-out wafer-level packaging has several advantages, such as lower thickness and better thermal resistance, warpage is one of the major challenges of the fan-out wafer-level packaging process to be minimized. There have been many studies investigating the effects of material properties and package design on warpage using finite element analysis. Current warpage simulations using finite element analysis have been routinely conducted with deterministic input parameters, although the parameter values are uncertain from the manufacturing point of view. This assumption may lead to a gap between the simulation and the field results. This paper presents an uncertainty analysis of wafer warpage in fan-out wafer-level packaging by using finite element analysis. Coefficient of thermal expansion of silicon is considered as a parameter with uncertainty. The warpage and the von Mises stress are calculated and compared with and without uncertainty.

Non-Invasive Cuffless Blood Pressure Monitoring System

2017 ◽  
pp. 174-194
Author(s):  
Harinderjit Singh ◽  
Dilip Kumar
Keyword(s):  
Blood Pressure ◽  
Blood Pressure Monitoring ◽  
Pulse Transit Time ◽  
The Body ◽  
Peak Time ◽  
Non Invasive ◽  
Inflatable Cuff ◽  
Measuring Devices ◽  
Cuffless Blood Pressure ◽  
Electrocardiogram Ecg

These days most of the Blood Pressure (BP) measuring devices are having inflatable cuff that is needed to be occluded on the patient's arm for measuring blood pressure. This technique is not suitable in cases where continuous measurement of BP is required. Therefore, this work is aimed at designing of non-invasive and continuously monitors the blood pressure by using Pulse Transit Time (PTT) technique. For taking out PTT both of the signals are extracted from the body of the patient with the help of bio sensors i.e. Electrocardiogram (ECG) sensor and Photoplethysmogram (PPG) sensor. PTT was measured by taking the peak to peak time difference of ECG signal and PPG signal and this PTT is indirectly correlated with blood pressure, based on which Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP) is calculated.

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