Written in EnglishRead online
|Statement||Marek-Jerzy Pindera, Robert S. Salzar, and Todd O. Williams.|
|Series||NASA contractor report -- 195337., NASA contractor report -- NASA CR-195337.|
|Contributions||Williams, Todd O., Salzar, Robert S., United States. National Aeronautics and Space Administration.|
|The Physical Object|
Download Optimization of residual stresses in MMC"s using compensating/compliant interfacial layers.
Optimization of Residual Stresses in MMC's Using Compensating/ Compliant Interfacial Layers Part II--OPTCOMP User's Guide \ Marek-Jerzy Pindera, Robert S.
Salzar, and Todd O. Williams University of Virginia Charlottesville, Virgini, May (NASA-CR) OPTIMIZATION OF RESIDUAL STRESSES IN MMC'S USING COMPENSATING/COMPLIANT INTERFACIAL LAYERS.
Optimization of residual stresses in MMC's using compensating/compliant interfacial layers. Part 2: OPTCOMP user's guide Article (PDF Available) June with 20 Reads.
Get this from a library. Optimization of residual stresses in MMC's using compensating/compliant interfacial layers. Part II, OPTCOMP user's guide. [M -J Pindera; Todd O Williams; Robert S Salzar; United States.
National Aeronautics and Space Administration.]. Optimization of residual stresses in MMC's through the variation of interfacial layer architectures and processing parameters Article (PDF Available) September with 30 Reads How we measure. Get this from a library. Optimization of residual stresses in MMC's through process parameter control and the use of heterogeneous compensating/complaint interfacial layers: OPTCOMP2 user's guide.
[M -J Pindera; Robert S Salzar; Langley Research Center.]. Optimization of Residual Stresses in MMC's and by using single or multiple interfacial layers with heterogeneous, two-phase microstructures inserted between the fibers and the surrounding matrix which act as compliant/compensating layers (Arnold et al.
[2,3]). The thickness of the interface has been shown to play a major role in reducing the matrix residual stress state and in addition to the CTE, the interface's elastic modulus E, yield stress ay, and hardening slope H in the idealized elasto-plastic case have proven to significantly effect the residual stress state in the interface layers.
Chapters in the first section of the book discuss the simulated hole drilling method, the slitting/crack compliance method, measuring residual stresses in homogeneous and composite glass materials using photoelastic techniques, and modeling residual stresses in composite materials.
MMCs, residual stresses are set up, which depend on the shape of the component as this controls the thermal gradient set up .-As the composite cools from the fabrication temperature, the metal matrix, having a CTE significantly higher than the ceramic reinforcement (5 times higher in the case of.
Residual stress MMCs are fabricated at elevated temperatures, which is an essential condition for diffusion bonding of the fiber/matrix interface. Later on, when they are cooled down to the ambient temperature, residual stresses (RS) are generated in the composite due to the mismatch between the coefficients of the metal matrix and fiber.
Optimization of Residual Stresses in the Surface Regions of Injection Moldings. Polymer-Plastics Technology and Engineering: Vol. 49, No. 1, pp. There are many methods to measure residual stresses. The methods are commonly grouped as non-destructive, semi-destructive and destructive or diffraction.
in the generation of residual stresses in samples of dif- ferent aluminium alloys milled at high speed, using an optimized indentation method. It is very important to note that, in these last three studies, the residual stress components were determined from data obtained using a UMM, avoiding the use of specific equipment and personnel.
Both magnitude and distribution of the residual stress can be critical to the performance that should be considered in the design of a e residual stresses in the surface of a component are generally undesirable since they can contribute to the major cause of fatigue failure, quench cracking and stress- corrosion cracking.
Moldex3D FEA Interface 31 Material 32 Comparison between shell and solid model 33 Element layers for solid model 38 Influence of process parameters on residual stress 40 Effect of Cooling 41 Effect of melt temperature 43 Effect of packing pressure 46 Effect of flow rate 48 6 CONCLUSION The residual stresses, together with the hardness, yield stress, tensile strength, etc., characterize the mechanical state of the machined affected layers.
The study of machining operations inducing residual stresses is particularly important when critical structural components are machined, especially, if the objective is to reach high.
and axial shear using finite element analysis. Thermal residual stresses, a result of the cooling down of the MMC from manufacturing temperature, is included in these analyses. This is referred to in the paper as thermal loading.
Exact method of applying the boundary conditions for combined thermal and shear loading are described. Residual Stress Measurement by X-ray Diffraction X-ray diffraction (XRD) is a well-established and accurate method to investigate the residual stress levels on the surface layers of crystalline materials.
X-ray diffraction for residual stress measurements is relatively cost-effective and widely available with portable and robotic.
residual stress for a carburised steel. The position of maximum compressive stress depends upon several factors such as, total case depth, severity of quench, steel hardenability etc.
In nitriding also a compressive residual stress develops in the surface layer. Low temperature nitriding imparts more residual stress as. Residual stresses are locked-in stresses within a metal object, even though the object is free of external forces.
These stresses are the result of one region of the metal being constrained by adjacent regions from expanding, contracting, or releasing elastic strains. Residual stresses can be tensile or compressive.
In fact, tensile and compressive residual stresses [ ]. the tangential residual stress to about psi. Lowering of the maximum residual stress to ab psi was achieved at ° F after 6 hr; however, lower tempera tures even for times as long as hr only reduced the maximum residual stress by about 25%.
Introduction The existence of residual stresses in. residual stresses into the specimens. The specimens were.
prepared by annealing, the use of a cavitating jet in air and by using a disc grinder. The annealing treatment re- leases residual stresses introduced by shape forming and increases the grain size.
The use of a cavitating jet in air introduces high equibiaxial compressive residual stresses. Young’s modulus and residual stress are important mechanical properties for the design of sophisticated SiC-based MEMS devices.
In particular, residual stresses are strongly dependent on the deposition conditions. Literature values for Young’s modulus range from to GPa, and residual stresses range from 98 to MPa. Practical Residual Stress Measurement Methods provides the reader with the information needed to understand key residual stress concepts and to make informed technical decisions about optimal choice of measurement technique.
Each chapter, written by invited specialists, follows a focused and pragmatic format, with subsections describing the.
Residual stresses are a common phenomenon in composite materials. They can either add to or significantly reduce material strength. Because of the increasing demand for high-strength, light-weight materials such as composites and their wide range of applications in the aerospace and automotive industries, in civil infrastructure and in sporting applications, it is critical that the residual.
This paper reviews predictive models developed for the development of residual stresses and shape distortions during the manufacturing of thermoset polymeric/composite materials. Different sources that produce residual stresses and shape changes in the laminated panels are described and reviewed.
An overview is presented on the characterisation and predictions of the phenomena resulting in. An exact elastic-plastic analytical solution for an arbitrarily laminated metal matrix composite tube subjected to axisymmetric thermo-mechanical and torsional loading is presented.
First, exact solutions for transversely isotropic and monoclinic (off-axis) elastoplastic cylindrical shells are. Residual stresses measured by X-ray diffraction can be described in terms of a simple con tinuum model if stress relaxation accompanies deformation and hardening.
The model demonstrates that the flow stress is split into separate mean stress and friction stress components arising from elastic and plastic heterogen eity.
An introductory and intermediate level handbook written in pragmatic style to explain residual stresses and to provide straightforward guidance about practical measurement methods.
Residual stresses play major roles in engineering structures, with highly beneficial effects when designed well, and catastrophic effects when ignored. With ever-increasing concern for product performance and.
Residual stress state plays an important role in the fatigue life of welded structures. The effect can be beneficial or detrimental, depending on the nature of residual stresses.
High frequency mechanical impact (HFMI) treatment is a postweld fatigue improvement technique for welded joints. Complete stress balance to net zero was not possible. However, the compressive multilayer was designed using appropriate thicknesses of niobia and silica layers to limit the stress within a value that could be mostly compensated by the Cr layer and exhibit stable properties.
Niobium Pentoxide. Compressive Residual Stress Optimization in Laser Peening of a Curved Geometry. Anoop Vasu and Ramana V. Grandhi.
Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH, Abstract. Laser Peening(LP) is a surface enha ncement technique that can delay crack nucleation by inducing compressive residual.
deeper residual stress profile. Dual peening,increases the magnit~de of compressive residual' stress. The e in residual stress at the' surface is 15 to 30 percent over conventional shot peened sample.
Significantly higher compressive residual stress is obtained in the samples when the surface oxidation products are. bTTDLE R". MOK r iG TABLEOFCONTENTS I.
INTRODUCTION 1 LRESIDUALSTRESSESINMETAL-MATRIXCOMPOSITES 1 -STRAINBEHAVIOROFMETAL-MATRIXCOMPOSITES 5 CHOBJECTIVESANDOVERVIEW 8 II.
EXPERIMENTALAPPROACH 10 CALMODELING 10 1. FiniteElementModeling 12 2. Assume: A uniaxial residual stress exists in a thin plate (Note a uniaxial residual stress field is unusual will generalize this discussion later) Hole-drilling Procedure: a) Special 3-element strain gage rosette bonded to the plate Note: gage elements arranged at constant radius r in a circular pattern - gage circuits are balanced in this.
Residual Stress Evaluation of Dissimilar Weld Joint Using Reactor Vessel Outlet Nozzle Mock-up Model (Report-1) Proceedings of ASME Pressure Vessels and Piping Division Conference, Volume 6: Materials and Fabrication, Parts A and B Chicago, Illinois, July 27–31,Paper No.
PVP, pp. – /PVP residual stresses that they might contain are not relieved. Before we can delve directly into the major effects of residual stresses, it is important to be sure that we all have the same under standing of just precisely what residual stresses are. This, in turn, requires some understanding of their origin.
Residual stresses can be measured by several different methods, as well as by combining various techniques. Donna Walker* Stressolvers Inc. Novi, Michigan R esidual stress is defined as the stress that remains in a body that is not being sub-jected to external forces.
Residual stress is caused by forming or processing oper. Residual stresses have the same role in a structure’s strength as common mechanical stresses. However, while stress due to external loads can be calculated with a degree of accuracy, residual stresses are difficult to foresee.
It is, therefore, very important to have a reliable method able to measure them directly with minimum damage to the. residual stress, including matrix cracking , yield strength [5,6], and dimensional stability .
It is therefore important to develop methods for the measurement and prediction of residual stresses in composite materials. This paper mainly presents measurements of the spatial distribution of residual stress in a metal matrix composite. The residual stresses so induced have been cbstr~ed in tungsten fiber/copper composites and in SiC whisker/ Al comp,sites and,',ere based on analyzed a one- .the residual stress changes for the part, it cannot easily be used to quantify the stress in the part.
Additionally, the color contour provides a composite stress state through the cross-section of the part and does not distinguish between Accounting for Residual Stress in Injection Molded Parts (Cont.) Erik Foltz.In continuum mechanics, stress is a physical quantity that expresses the internal forces that neighbouring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material.
For example, when a solid vertical bar is supporting an overhead weight, each particle in the bar pushes on the particles immediately below it.