Residual Stresses and Damage in Multilayer Ceramic/Metal Packages

1986 ◽  
Vol 72 ◽  
Author(s):  
A. G. Evans ◽  
C. H. Hsueh
Keyword(s):  
Residual Stresses ◽  
Mechanical Damage ◽  
Thermal Contraction ◽  
Densification Rate ◽  
Porous Metals ◽  
Material Parameters ◽  
Dense Ceramic ◽  
Induced Stresses ◽  
Multilayer Ceramic ◽  
Flow Laws

AbstractMultilayer ceramic/metal modules are subject to stresses that develop both upon co-sintering and upon cooling. The sources and magnitudes of these stresses are described and discussed. The co-sintering induced stresses derive from densification-rate mismatch and can be analyzed in terms of constitutive laws that describe the densification and creep of partially dense ceramic and metal bodies. Cooling induced stresses are associated with thermal contraction mismatch and are strongly influenced by the plastic flow laws for porous metals. Typical stresses produced during co-sintering and cooling are calculated and techniques for minimizing such stresses are discussed and analyzed. Mechanical damage, manifest as brittle cracks and creep cracks, are also described and analyzed. Critical values of material parameters that exclude extensive crack damage are then emphasized, based on models of crack propagation.

scholarly journals Residual Stress Measurements in Mo/CuCrZr Tiles Using Neutron Diffraction

2008 ◽  
Vol 59 ◽  
pp. 299-303
Author(s):  
K. Mergia ◽  
Marco Grattarola ◽  
S. Messoloras ◽  
Carlo Gualco ◽  
Michael Hofmann
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Heat Sink ◽  
High Yield ◽  
Fusion Reactors ◽  
Plasma Facing Components ◽  
Induced Stresses ◽  
Compliant Layer

In plasma facing components (PFC) for nuclear fusion reactors tungsten or carbon based tiles need to be cooled through a heat sink. The joint between the PFC and the heat sink can be realized using a brazing process through the employment of compliant layer of either a low yield material, like copper, or a high yield material, like molybdenum. Experimental verification of the induced stresses during the brazing process is of vital importance. Strains and residual stresses have been measured in Mo/CuCrZr brazed tiles using neutron diffraction. The strains and stresses were measured in Mo tile along the weld direction and at different distances from it. The experimental results are compared with Finite Element Simulations.

Limitation of Distortion in Friction Stir Welded (FSW) Panels Using Needle Peening

2010 ◽  
Vol 638-642 ◽  
pp. 1203-1208 ◽  
Author(s):  
Simon Larose ◽  
Laurent Dubourg ◽  
C. Perron ◽  
Mohammad Jahazi ◽  
Priti Wanjara
Keyword(s):  
Residual Stresses ◽  
Shot Peening ◽  
Sheet Material ◽  
Travel Speed ◽  
Needle Size ◽  
Friction Stir ◽  
Average Value ◽  
Aa 2024 ◽  
Induced Stresses ◽  
Needle Diameter

Friction stir welding (FSWing) induces residual stresses and distortions in welded structures. Such residual stresses reduce the fatigue life of welded components, while the induced distortions prevent the welding of large or thin components. In the present study, needle peening was used to induce additional residual stresses in 2.3-mm thick (FSWed) aluminum alloy (AA) 2024-T3 sheets. This was done with the objective to counterbalance the welding-induced stresses and thus reduce the overall stresses and distortions. The needle peening process, which stems from shot peening, consists of hammering a surface using cylindrical spherical ended shots sliding back and forth in a treatment head. An instrumented needle peening machine was used to carry out peening on as-received (or bare) and bead-on-plate FSWed AA2024-T3 material. In both cases, the width of the peening area corresponded to that of a typical weld. The influence of the peening process parameters such as needle size, applied power and travel speed on the surface quality and magnitude of the induced distortions were evaluated. The results indicate that, by increasing the needle diameter from 1.2 mm to 2.0 mm, the peening-induced deflection on bare sheet material increased by an average value of 27% while the roughness average, Ra, decreased by an average value of 47%. It was also found that a surface finish qualitatively similar to that of conventional shot peening could be obtained by using appropriate needle peening trajectories. Finally, needle peening with an applied power of 10% was sufficient for eliminating 37% of the welding-induced transverse curvature and 82% of the welding-induced longitudinal curvature.

Modelling of Residual Stresses in Dental Restorative Polymer Based Materials

2015 ◽  
Vol 760 ◽  
pp. 251-256
Author(s):  
Giuseppe Lamanna ◽  
Raffaele Sepe
Keyword(s):  
Residual Stresses ◽  
Coming Out ◽  
Input Data ◽  
Thermal Shrinkage ◽  
Test Case ◽  
Chemical Shrinkage ◽  
Thermal Contraction ◽  
Curing Shrinkage ◽  
Photo Curing ◽  
Dental Restorative

A methodology for residual stresses calculations is proposed. Common photo-curing dental restorative materials under different C-factors are considered as case studies. Reaction kinetics, curing shrinkage, and viscoelasticity map were required as input data on a structural FE solver. Post cure effects were considered in order to quantify the residual stresses coming out from natural contraction with respect to those debited to the chemical shrinkage. The analysis showed for a given test case that stresses build-up due to the thermal contraction (after the completion of restoration) are comparable with those emerging due to thermal shrinkage.

Residual Stresses in Multilayer Ceramic Capacitors: Measurement and Computation

2003 ◽  
Vol 125 (4) ◽  
pp. 506-511 ◽  
Author(s):  
Jaap M. J. den Toonder ◽  
Christian W. Rademaker ◽  
Ching-Li Hu
Keyword(s):  
Residual Stresses ◽  
Computational Study ◽  
Three Dimensional ◽  
Sintering Process ◽  
Multilayer Ceramic Capacitors ◽  
Ceramic Capacitors ◽  
Dimensional Finite Element ◽  
Multilayer Ceramic ◽  
Thermomechanical Reliability ◽  
Three Dimensional Finite Element

In this paper, we present a combined experimental and computational study of the thermomechanical reliability of multilayer ceramic capacitors (MLCC’s). We focus on residual stresses introduced into the components during the cooling down step of the sintering process. The technique of microindentation turned out to be a useful method to measure the stresses locally. The computations were done with three-dimensional finite element simulations. We find that the cooling step introduces compressive in-plane stresses in the ceramic layers. There is reasonably good overall agreement between the residual stresses obtained from the indentation experiments and the numerical simulations. Some discrepancies do exist, though, for measurements on cross-sectioned MLCC’s. Possible reasons for the differences are discussed.

Testing of a Dual Field Magnetic Flux Leakage (MFL) Inspection Tool for Detecting and Characterizing Mechanical Damage Features

2008 ◽  
Author(s):  
Alex Rubinshteyn ◽  
Steffen Paeper ◽  
Bruce Nestleroth
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Residual Stresses ◽  
High Field ◽  
Mechanical Damage ◽  
Magnetic Flux Leakage ◽  
Low Field ◽  
Field Unit ◽  
Low Magnetic Field ◽  
Flux Leakage

Battelle has developed dual field magnetic flux leakage (MFL) technology for the detection and characterization of mechanical damage to pipelines. The basic principle involves the use of a high magnetic field between 140 and 180 Oersted (11.1 to 14.3 kA/m) and the use of a low magnetic field between 50 and 70 Oersted (4 to 5.6 kA/m). At high magnetic field levels, the flux leakage signal is primarily influenced by changes in the geometry of a pipe wall. At low magnetic field levels, the MFL signal is due to residual stresses and metallurgical changes as well as geometry changes to the pipe caused by mechanical damage and wall thinning. A decoupling signal processing method developed by Battelle is used to isolate the portion of the mechanical damage signals due to metallurgical damage and residual stresses, which allows the characteristics of a dent-gouge feature to be more clearly differentiated. The decoupling method involves first scaling down the high field signal to the level of the low field signal, and then subtracting it from the low field signal. This produces a decoupled signal that is primarily influenced by the residual stresses and metallurgical changes caused by mechanical damage. Rosen has developed a tool to test the dual field technology and is evaluating tool performance by running the tool in a 30 inch diameter pipeline segment. The tool itself is composed of three separate modules coupled together: a high field unit downstream of a low field unit which is downstream of a caliper arm unit that is used to detect and characterize reductions in the internal diameter. The general and magnetic design of the tool, along with the scaling algorithm is discussed. Results from a pull test in a pipe section with dents whose geometry has been independently characterized are also discussed. This work is partially funded by the U.S. Department of Transportation, Pipeline and Hazardous Materials Safety administration (DOT PHMSA) and the Pipeline Research Council International, Inc. (PRCI).

Development of a Novel Electromagnetic Quantitative Residual Stress Sensor for Characterization of Steel Pipeline Mechanical Damage

2012 ◽  
Author(s):  
Angelique N. Lasseigne ◽  
Kamalu M. Koenig ◽  
Joshua E. Jackson
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Real Time ◽  
Stress Measurement ◽  
Pipeline Steel ◽  
Mechanical Damage ◽  
Steel Pipeline ◽  
Stress Sensor ◽  
Integrity Assessment ◽  
Rapid Characterization

Nondestructive residual stress mapping of damage in pipeline steel has been demonstrated as a new approach for pipeline integrity management. The handheld system for rapid characterization pipelines has been used on dents and wrinkles, two of the most common forms of mechanical deformation. The ability to compare residual stresses with design stresses will allow for a much more accurate criteria for use in fitness-for-service and improved modeling of pipeline stresses. As the capabilities of in-line inspection technologies continue to improve, operators are often faced with thousands of indications that require examination. Accurate assessment of residual stresses will provide a more effective method of combatting the most common form of pipeline failures, mechanical damage. The residual stresses associated with the mechanical damage forms the basis for the nucleation and growth of cracks at areas with the highest residual stresses. Quantitative, real-time knowledge of the through-thickness residual stress levels associated with the mechanical damage will enable enhanced Risk-Based Inspection and drastically improve pipeline integrity. The development of a non-destructive, quantified residual stress measurement system to evaluate the damage severity on pipeline steels through the structural coatings (without any removal) will enable improved integrity assessment and reduce the number of unnecessary removal and replacement activities. The development of a real-time, through-thickness residual stress sensor to assess steel pipeline mechanical damage is presented in this paper.

Estimation of Residual Stresses in Hydraulically Expanded Tube-to-Tubesheet Joints

1998 ◽  
Vol 120 (2) ◽  
pp. 129-137 ◽  
Author(s):  
M. Allam ◽  
A. Chaaban ◽  
A. Bazergui
Keyword(s):  
Residual Stresses ◽  
Heat Exchangers ◽  
Structural Integrity ◽  
Theoretical Method ◽  
Pressure Level ◽  
The Finite Element Method ◽  
Material Parameters ◽  
Deviation Analysis ◽  
Upper Limit ◽  
Expansion Pressure

The knowledge of residual stresses introduced in the tubes of heat exchangers during their expansion in the tubesheet holes is important because of their effect on the structural integrity of components. This paper presents a simplified theoretical method to calculate the maximum residual stresses introduced in the transition zone of expanded tube-to-tubesheet joint. The higher positive values of tensile residual stresses and their corresponding axial locations are determined by using a standard deviation analysis. The validation of the proposed equations was accomplished by comparing their results to those obtained by the finite element method for some arbitrary cases. An upper limit has been imposed on the expansion pressure level, depending on the combination of the geometrical and material parameters that are involved in the design of the tube-to-tubesheet joints.

Determination of Residual Stress of Hard Film/Soft Substrate Specimens via Unloading Results of Nanoindentation Tests

2011 ◽  
Vol 328-330 ◽  
pp. 843-848
Author(s):  
Huu Hung Nguyen ◽  
Pal Jen Wei ◽  
Jen Fin Lin
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Soft Substrate ◽  
Large Depth ◽  
Cube Corner ◽  
Induced Stresses ◽  
Depth Curves

A method used to determine the residual stress in a hard film deposited on a soft substrate via the unloading load-depth curves was proposed. The unloading curves with transitional behaviors were used to determine the film deflection stiffness, and then the residual stresses were obtained. Significant extra stresses were induced by a cube corner indenter at large depth. In contrast, the indentation-induced stresses could be neglected in cases of Berkovich indentation at relatively small depths.

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