Hybrid Analytical and Experimental Method for Characterization of Thin Multilayer Bonded Structures Subject to Thermal Loading

2018 ◽  
Author(s):  
Alireza Shirazi ◽  
Hua Lu ◽  
Ahmad Varvani
Keyword(s):  
Thermal Cycling ◽  
Material Properties ◽  
Accurate Determination ◽  
High Accuracy ◽  
Thin Layers ◽  
Material Behavior ◽  
Interfacial Stress ◽  
Bonding Layer ◽  
Global Deformation ◽  
Warpage Deformation

This study is presenting a non-local closed-form solution for interfacial stress/strain and the warpage deformation for thin trilayer plate structures under thermal cycling. Based on the theory of geometric scale dependency of the material behavior, the material properties of a thin multi-layer inter-bonded structures substantially differ from those determined based on the bulk material samples. Hence the real mechanical properties for such thin layers are often unavailable and difficult to obtain. This paper puts forward a method to provide a solution for thermomechanical behavior of trilayer constituents with high accuracy at real scale. Present study demonstrates that the constitutive behavior of multilayer plate’s constituents can be inversely determined so long as the plate’s global deformation can be made available by measurement. To achieve most accurate determination of the material properties, measurements with high accuracy is required. The paper also presents the advanced method of shadow moiré that have applied to obtain warpage deformation of real life trilayer test specimens under thermal cycling. Using this method, the experimentally determined global deformation (warpage) of a trilayer structure were correlated with the analytical model solved for warpage deformation. The correlation was then progressively optimized to result in material properties of the constituents. The bonding layer properties are called determined, once the correlation reaches over 85%. There exist a variety of different multilayer bonded structures, which are usually made with advanced manufacturing processes. Regardless of design layout and materials constitutive relations, the application can be implemented in characterizing multiply stacked trilayer structures.

Modeling the Effect of Material Behavior and Mild Thermal Treatments on Collapse Resistance of UOE Pipes

2012 ◽  
Author(s):  
Santiago Serebrinsky ◽  
Luciano Mantovano ◽  
Marcos de Souza ◽  
Martín Valdez ◽  
Hugo Ernst ◽  
...  
Keyword(s):  
Flow Stress ◽  
Thermal Cycling ◽  
Accurate Determination ◽  
Large Diameter ◽  
Primary Objective ◽  
Material Behavior ◽  
Brazilian Coast ◽  
Main Concern ◽  
Thermal Treatments ◽  
Element Analysis

Oil exploration and production of offshore sources is continuously shifting towards increasing depths and more severe environmental conditions. Ultra deep waters are an objective in, e.g., the pre-salt layer off the Brazilian coast and in the Gulf of Mexico. Under these conditions, resistance to collapse of pipelines is a main concern. Increasing the collapse pressure pc is thus a primary objective, which would lead to a reduction of material and installation costs. To increase pc, it is fundamental to understand which variables affect it, and how to control these variables. For instance, it is well known that ovality, residual stresses, and material constitutive behavior have a direct effect on pc. Current efforts for improving pc of large diameter UOE pipes include an increase in flow stress by the application of a thermal cycle, similar to those typical of coating processes. These thermal treatments recover at least part of the early yielding due to the Bauschinger effect that develops during the collapse test, after the expansion stage. Predictive modeling of pc, based on an appropriate set of input variables, allows for an adequate design of deep- and ultra-deep water projects. In the present work, an assessment by finite element analysis of the requirements on material characterization tests for a reliable prediction of pc has been performed. The most appropriate testing direction is the transverse compression. Moreover, since for large diameter pipes the plastic strain levels attained at collapse are often below 0.2%, the sample should allow for an accurate determination of compression behavior in this very low deformation range. This is particularly relevant for cold-formed pipes, as with the UOE process. Based on these guidelines, a testing sample geometry and compression data processing methodology has been designed. The methodology has been applied to a series of UOE processed pipes that had been thermally treated. On one hand, compression samples were extracted and used for the FE calculation of pc. On the other hand, collapse tests were performed on the same pipes. Both the absolute values of pc, and the enhancement of pc due to thermal cycling, were accurately predicted. In addition, both the flow stress after thermal cycling, and the measured pc values, clearly show that the fabrication factor αfab used in the standard DNV OS-F101 should be set to αfab≥1 for an adequate rating of the pipes.

Determination of Charge Coefficient of Piezoelectric Films Using a Combined Finite Element Model and Dynamic Loading Technique

2020 ◽  
Vol 835 ◽  
pp. 229-242
Author(s):  
Oboso P. Bernard ◽  
Nagih M. Shaalan ◽  
Mohab Hossam ◽  
Mohsen A. Hassan
Keyword(s):  
Finite Element ◽  
Dynamic Loading ◽  
Material Properties ◽  
Accurate Determination ◽  
Substrate Material ◽  
Experimental Results ◽  
Piezoelectric Composite ◽  
Piezoelectric Film ◽  
Piezoelectric Charge

Accurate determination of piezoelectric properties such as piezoelectric charge coefficients (d33) is an essential step in the design process of sensors and actuators using piezoelectric effect. In this study, a cost-effective and accurate method based on dynamic loading technique was proposed to determine the piezoelectric charge coefficient d33. Finite element analysis (FEA) model was developed in order to estimate d33 and validate the obtained values with experimental results. The experiment was conducted on a piezoelectric disc with a known d33 value. The effect of measuring boundary conditions, substrate material properties and specimen geometry on measured d33 value were conducted. The experimental results reveal that the determined d33 coefficient by this technique is accurate as it falls within the manufactures tolerance specifications of PZT-5A piezoelectric film d33. Further, obtained simulation results on fibre reinforced and particle reinforced piezoelectric composite were found to be similar to those that have been obtained using more advanced techniques. FE-results showed that the measured d33 coefficients depend on measuring boundary condition, piezoelectric film thickness, and substrate material properties. This method was proved to be suitable for determination of d33 coefficient effectively for piezoelectric samples of any arbitrary geometry without compromising on the accuracy of measured d33.

scholarly journals Impact of residual stress evoked by pyramidal embossing on the magnetic material properties of non-oriented electrical steel

2021 ◽  
Author(s):  
Ines Gilch ◽  
Tobias Neuwirth ◽  
Benedikt Schauerte ◽  
Nora Leuning ◽  
Simon Sebold ◽  
...  
Keyword(s):  
Magnetic Material ◽  
Residual Stress ◽  
Magnetic Flux ◽  
Material Properties ◽  
Electrical Steel ◽  
Maximum Energy ◽  
Material Behavior ◽  
Electrical Machine ◽  
Element Analysis ◽  
Steel Sheets

AbstractTargeted magnetic flux guidance in the rotor cross section of rotational electrical machines is crucial for the machine’s efficiency. Cutouts in the electrical steel sheets are integrated in the rotor sheets for magnetic flux guidance. These cutouts create thin structures in the rotor sheets which limit the maximum achievable rotational speed under centrifugal forces and the maximum energy density of the rotating electrical machine. In this paper, embossing-induced residual stress, employing the magneto-mechanical Villari effect, is studied as an innovative and alternative flux barrier design with negligible mechanical material deterioration. The overall objective is to replace cutouts by embossings, increasing the mechanical strength of the rotor. The identification of suitable embossing geometries, distributions and methodologies for the local introduction of residual stress is a major challenge. This paper examines finely distributed pyramidal embossings and their effect on the magnetic material behavior. The study is based on simulation and measurements of specimen with a single line of twenty embossing points performed with different punch forces. The magnetic material behavior is analyzed using neutron grating interferometry and a single sheet tester. Numerical examinations using finite element analysis and microhardness measurements provide a more detailed understanding of the interaction of residual stress distribution and magnetic material properties. The results reveal that residual stress induced by embossing affects magnetic material properties. Process parameters can be applied to adjust the magnetic material deterioration and the effect of magnetic flux guidance.

Study of Transport Through Low-Temperature GaAs Surface Insulator Layers

1991 ◽  
Vol 241 ◽  
Author(s):  
J. P. Ibbetson ◽  
L.-W. Yin ◽  
M. Hashemi ◽  
A. C. Gossard ◽  
U. K. Mishra
Keyword(s):  
Material Properties ◽  
Surface Effect ◽  
Thin Layers ◽  
Gate Insulator ◽  
High Resistivity ◽  
Growth Surface ◽  
Insulator Layer ◽  
Insulator Layers ◽  
Low Temperature Gaas ◽  
Effective Buffer

ABSTRACTSince epilayers of GaAs grown at low substrate temperature (LTGaAs) and annealed at 600°C were first demonstrated to be an effective buffer layer for eliminating backgating effects, the material properties and electronic characteristics of bulk LTGaAs have been actively investigated. Less attention has been paid to thin layers of LTGaAs (∼2000Å), although these have been shown to improve gate-to-drain breakdown characteristics when incorporated as the surface insulator layer in GaAs MISFET's. In bulk LTGaAs that has been annealed for 10 minutes at 600°C, the formation of arsenic precipitates with a density of 1018 cm-3 has been observed. These are considered to be at least partially responsible for the high resistivity of LTGaAs2. While the exact mechanism of precipitate formation is currently unknown, it would seem reasonable to expect the availability of the growth surface to have a significant effect on any defect redistribution during the anneal. This surface effect would become increasingly apparent as the LTGaAs layer thickness was decreased. It is desirable for MISFET applications that the LTGaAs gate insulator layer be as thin as possible, whilst maintaining high breakdown, in order to maximize device transconductance. To achieve this, it is important to understand how the observed bulk features (such as ∼60Å size arsenic precipitates) are affected in thin LTGaAs layers

Thermal Cycling Simulation during Remelting Process of the Steel ASTM A743-CA6NM

2014 ◽  
Vol 1082 ◽  
pp. 100-105
Author(s):  
Camila Almeida Martins ◽  
Jhon Jairo Ramirez-Behainne
Keyword(s):  
Numerical Model ◽  
Thermal Cycling ◽  
Material Properties ◽  
Three Dimensional ◽  
Fusion Line ◽  
Maximum Deviation ◽  
Experimental Measurements ◽  
Ansys Fluent ◽  
Simplifying Assumptions ◽  
Volume Method

This study aimed to model numerically the thermal cycling resulting from the steel ASTM A743-CA6NM remelting process. The problem was solved with the support of the commercial software ANSYS / FLUENT ® 14.5 for the three-dimensional case using the finite volume method. The following simplifying assumptions were adopted: heat loss by natural convection, absence of radiation, no phase change, concentrated heat source, and thermophysical properties independent of temperature. The results were analyzed for two different current intensities: 90A and 130A, and compared with experimental measurements. The peak temperatures of the thermocouples near the fusion line for the current of 130A were well represented by the numerical model, with a maximum deviation of 9.62%. In the case of the more remote thermocouples from the fusion line, the best results were obtained for the current of 90A, not exceeding 5% of deviation. In general, it was found that the tested body is heated faster than in simulations. This can be considered as a consequence of the simplification in material properties, which were assumed constants with temperature. The results of this study demonstrate that, given the adopted simplifications, the numerical model was able to satisfactorily reproduce the experimentally measured thermal cycles.

FEA Based Reliability Predictions for PBGA Packages Subjected to Isothermal Aging Prior to Thermal Cycling

2015 ◽  
Author(s):  
Munshi Basit ◽  
Mohammad Motalab ◽  
Jeffrey C. Suhling ◽  
John L. Evans ◽  
Pradeep Lall
Keyword(s):  
Finite Element ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Isothermal Aging ◽  
Material Behavior ◽  
Lead Free ◽  
Stress Strain ◽  
Solder Material ◽  
Free Solder ◽  
Temperature Aging

The microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal aging and/or thermal cycling environments. In our prior work on aging effects, we have demonstrated that the observed material behavior degradations of Sn-Ag-Cu (SAC) lead free solders during room temperature aging (25 C) and elevated temperature aging (50, 75, 100, 125, and 150 C) were unexpectedly large. The measured stress-strain data demonstrated large reductions in stiffness, yield stress, ultimate strength, and strain to failure (up to 50%) during the first 6 months after reflow solidification. In this study, we have used both accelerated life testing and finite element modeling to explore how prior isothermal aging affects the overall reliability of PBGA packages subjected to thermal cycling. In the experimental work, an extensive test matrix of thermal cycling reliability testing has been performed using a test vehicle incorporating several sizes (5, 10, 15, 19 mm) of BGA daisy chain components with 0.4 and 0.8 mm solder joint pitches (SAC305). PCB test boards with 3 different surface finishes (ImAg, ENIG and ENEPIG) were utilized. In this paper, we concentrate on the reporting the results for a PBGA component with 15 mm body size. Before thermal cycling began, the assembled test boards were divided up into test groups that were subjected to several sets of aging conditions (preconditioning) including 0, 6, and 12 months aging at T = 125 °C. After aging, the assemblies were subjected to thermal cycling (−40 to +125 °C) until failure occurred. The Weibull data failure plots have demonstrated that the thermal cycling reliabilities of pre-aged assemblies were significantly less than those of non-aged assemblies. A three-dimensional finite element model of the tested 15 mm PBGA packages was also developed. The cross-sectional details of the solder ball and the internal structure of the BGA were examined by scanning electron microscopy (SEM) to capture the real geometry of the package. Simulations of thermal cycling from −40 to 125 C were performed. To include the effects of aging in the calculations, we have used a revised set of Anand viscoplastic stress-strain relations for the SAC305 Pb-free solder material that includes material parameters that evolve with the thermal history of the solder material. The accumulated plastic work (energy density dissipation) was used is the failure variable; and the Darveaux approach to predict crack initiation and crack growth was applied with aging dependent parameters to estimate the fatigue lives of the studied packages. We have obtained good correlation between our new reliability modeling procedure that includes aging and the measured solder joint reliability data. As expected from our prior studies on degradation of SAC material properties with aging, the reliability reductions were more severe for higher aging temperature and longer aging times.

Gymnasium Building Materials Performance-Type Research

2013 ◽  
Vol 712-715 ◽  
pp. 831-834
Author(s):  
Xiao Jie Chen
Keyword(s):  
Material Properties ◽  
Building Materials ◽  
External Environment ◽  
Material Design ◽  
Control Technique ◽  
Bonding Layer ◽  
Important Thing ◽  
Building Enclosure ◽  
Visual Structure ◽  
And Control

Materials in sports building space plays not only a supporting role but also an important part of building exhibition. With the rise of intelligent and ecological buildings, as a building enclosure material properties and role will become more prominent. New advances in technology make material has been not just enclosure system, but with the external environment for building dialogue interface, visual, structure and control technique of bonding layer. How effectively function technology element integration in material artistic expressive force is the important thing in current material design.

A Model of Magnetorheological Grease using Machine Learning Method

2018 ◽  
Vol 775 ◽  
pp. 191-197 ◽  
Author(s):  
Irfan Bahiuddin ◽  
Saiful Amri Mazlan ◽  
Mohd. Ibrahim Shapiai ◽  
Norzilawati Mohamad ◽  
Fitrian Imaduddin
Keyword(s):  
Material Properties ◽  
Development Process ◽  
High Accuracy ◽  
Machine Learning Method ◽  
Learning Method ◽  
Mean Square ◽  
Composition Effect ◽  
Machine Method ◽  
Mr Fluid ◽  
Learning Machine

Magnetorheological (MR) grease is a promising material to replace MR fluid because the advantage in term of stability and less possibility to leaking. To improve the material properties, an accurate model can be critical for reducing the time and cost of the development process. A model has been developed to predict MR fluid material properties by including the composition. However, the model may need adjustment and cannot predict other essential rheology parameters, such as viscosity, apparent viscosity, shear rate, and shear stress. Therefore, the technical novelty of this paper is to propose a model with composition as one of the inputs using extreme learning machine method. A scoring system is also introduced to quantify the significance of the composition effect toward the MR grease performance. Then, the model is simulated and compared with experimental data. The performance shows high accuracy estimation with normalized root mean square error about 1.25%.

An Expression of Strain Energy with Couple Stresses

1984 ◽  
Vol 8 (2) ◽  
pp. 63-69
Author(s):  
S.K. Lakhanpal
Keyword(s):  
Material Properties ◽  
Strain Energy ◽  
Load Transfer ◽  
Modern Technology ◽  
Material Behavior ◽  
Couple Stresses ◽  
Energy Expression

Modern Technology has required a continuous search for better materials. Hence, the desire among engineers to study the material properties rigorously. Throughout the literature, the concept of load transfer is based on linear stresses. However, the material behavior is better defined when load transfer is considered to be by couple stresses, in addition to linear stresses. The strain energy expression is an important tool for the study of the material. With this in mind, an expression with couple stresses included is developed.

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