Theory and validation of the master ply concept for invariant-based stiffness of composites

2017 ◽  
Vol 52 (12) ◽  
pp. 1699-1708 ◽  
Author(s):  
Sung Kyu Ha ◽  
Carlos Alberto Cimini
Keyword(s):  
Constitutive Relations ◽  
Theoretical Background ◽  
Design Tool ◽  
Material System ◽  
High Modulus ◽  
Background Theory ◽  
Material Systems ◽  
Theoretical Predictions ◽  
Epoxy Material ◽  
Normalized Parameters

The objective of this paper is to unveil the background theory behind the universal master ply assumption, based on the invariant approach, to describe ply elastic properties. It was demonstrated that using ply-based constitutive relations, trace-normalized stiffness properties can be derived for different materials. Theoretical predictions for trace-normalized parameters were plotted as functions of the unidirectional ply longitudinal modulus ( Ex), which defines the particular material system. Ply stiffness extensive empirical data were obtained from literature for four types of material systems (high modulus carbon/epoxy, standard modulus carbon/epoxy, aramid/epoxy, and glass/epoxy) and correlated quite well to theoretical predictions. Theoretical curves presented a nonlinear region for low Ex which gradually evolves to a plateau as Ex increases. It was verified that the master ply concept averaging the trace-normalized ply stiffness matrix elements can be applied for high modulus carbon/epoxy, standard modulus carbon/epoxy, and aramid/epoxy material systems. However, glass/epoxy systems can not be represented by this concept. The exposed theoretical background supports trace-based approach and enhances its effectiveness as a design tool, encompassing all the consequent advantages.

Application of Wide-Band Ultrasound for the Detection of Angled Crack Features in Oil and Gas Pipelines

2018 ◽  
Author(s):  
Willem Vos ◽  
Petter Norli ◽  
Emilie Vallee
Keyword(s):  
Large Scale ◽  
Crack Detection ◽  
Oil And Gas ◽  
Wide Band ◽  
Theoretical Background ◽  
Proof Of Concept ◽  
Offshore Pipelines ◽  
Large Scale Testing ◽  
Theoretical Predictions ◽  
Set Up

This paper describes a novel technique for the detection of cracks in pipelines. The proposed in-line inspection technique has the ability to detect crack features at random angles in the pipeline, such as axial, circumferential, and any angle in between. This ability is novel to the current ILI technology offering and will also add value by detecting cracks in deformed pipes (i.e. in dents), and cracks associated with the girth weld (mid weld cracks, rapid cooling cracks and cracks parallel to the weld). Furthermore, the technology is suitable for detection of cracks in spiral welded pipes, both parallel to the spiral weld as well as perpendicular to the weld. Integrity issues around most features described above are not addressed with ILI tools, often forcing operators to perform hydrostatic tests to ensure pipeline safety. The technology described here is based on the use of wideband ultrasound inline inspection tools that are already in operation. They are designed for the inspection of structures operating in challenging environments such as offshore pipelines. Adjustments to the front-end analog system and data collection from a grid of transducers allow the tools to detect cracks in any orientation in the line. Description of changes to the test set-up are presented as well as the theoretical background behind crack detection. Historical development of the technology will be presented, such as early laboratory testing and proof of concept. The proof of concept data will be compared to the theoretical predictions. A detailed set of results are presented. These are from tests that were performed on samples sourced from North America and Europe which contain SCC features. Results from ongoing testing will be presented, which involved large-scale testing on SCC features in gas-filled pipe spools.

Effect of Light Exposure Conditions on the Light-Induced Degradation in Amorphous Silicon Alloy Solar Cells

1991 ◽  
Vol 219 ◽  
Author(s):  
Y. Nakata ◽  
A. Yokota ◽  
H. Sannomiya ◽  
S. Moriuchi ◽  
Y. Inoue ◽  
...  
Keyword(s):  
Solar Cells ◽  
Light Exposure ◽  
Analytical Formula ◽  
Theoretical Background ◽  
Test Method ◽  
Exposure Condition ◽  
Solar Simulator ◽  
Silicon Alloys ◽  
Normalized Parameters ◽  
Photovoltaic Parameters

ABSTRACTLight-induced changes in current-voltage characteristics of amorphous single-junction solar cells made of silicon alloys, a-SiC, a-Si, and a-SiGe have been studied systematically. The effect of the light intensity and the bias voltage on the light-induced degradation in the conversion efficiency and other photovoltaic parameters has been clarified quantitatively, and it has been shown that the light-induced degradation characteristics of the photovoltaic parameters can be described by a single function of some normalized parameters of exposure condition. Theoretical background for the experimental results is also examined and discussed by applying a defect creation model modified to an active layer of the a-Si alloy solar cells. Utilizing these analytical formula, we propose an accelerated test method by solar simulator indoor measurement instead of natural sunlight outdoor testing.

Recent Progress in III-Nitride Tunnel Junction-Based Optoelectronics

2019 ◽  
Vol 28 (01n02) ◽  
pp. 1940012
Author(s):  
Zane Jamal-Eddine ◽  
Yuewei Zhang ◽  
Siddharth Rajan
Keyword(s):  
Tunnel Junction ◽  
Recent Progress ◽  
Tunnel Junctions ◽  
Optoelectronic Devices ◽  
Material System ◽  
Novel Device ◽  
Unique Material ◽  
Material Systems ◽  
Device Applications ◽  
Commercial Device

Tunnel junctions have garnered much interest from the III-Nitride optoelectronic research community within recent years. Tunnel junctions have seen applications in several material systems with relatively narrow bandgaps as compared to the III-Nitrides. Although they were initially dismissed as ineffective for commercial device applications due to high voltage penalty and on resistance owed to the wide bandgap nature of the III-Nitride material systems, recent development in the field has warranted further study of such tunnel junction enabled devices. They are of particular interest for applications in III-Nitride optoelectronic devices in which they can be used to enable novel device designs which could potentially address some of the most challenging physical obstacles presented with this unique material system. In this work we review the recent progress made on the study of III-Nitride tunnel junction-based optoelectronic devices and the challenges which are still faced in the field of study today.

scholarly journals Fuel-Water emulsion impact on miniature gas turbine pollutant emission

2019 ◽  
Vol 137 ◽  
pp. 01046 ◽  
Author(s):  
Maciej Chmielewski ◽  
Marian Gieras ◽  
Paweł Niszczota
Keyword(s):  
Gas Turbine ◽  
Theoretical Background ◽  
Pollutant Emissions ◽  
Water Phase ◽  
Pollutant Emission ◽  
Combustion Mechanism ◽  
Water Emulsion ◽  
Theoretical Predictions ◽  
Numerical Research ◽  
Distributed Energy Generation

The innovative use of the Fuel-Water emulsion in a small gas turbine for distributed energy generation is proposed. The FWE in this situation is considered as a nonhomogeneous mix of water and fuel, where water is a dispersed phase in the continuous fuel phase with an addition of surfactants. The Fuel-Water emulsion has a great mainly due to two mechanisms: temperature reduction due to heat absorption by the water phase and enhanced homogeneity of the fuel-air mixture due to micro-explosion of the superheated water phase inside the emulsion droplet. Proposed paper presents theoretical background on Fuel-Water emulsion combustion mechanism. Finally initial results of numerical research of fuel-water emulsion injection to miniature gas turbine are presented. Theoretical predictions of NOX pollutant emissions are compared with accuracy of the gas analyzer planned to be used during experimental research.

scholarly journals Experimental and semianalytical investigation of X850 ± IM190 CFRP bolted joints

2020 ◽  
Vol 29 ◽  
pp. 096369351989500
Author(s):  
Boling He
Keyword(s):  
Bolted Joints ◽  
Design Parameters ◽  
Material System ◽  
Commercial Aircraft ◽  
Reinforced Polymer ◽  
Epoxy Material ◽  
Static Tensile ◽  
Curing Method ◽  
Tensile Experiment ◽  
Bolt Diameter

Considering the fact that the foundation data for a new X850 ± IM190 carbon/epoxy material system adopted in commercial aircraft industry are extremely scarce in the literature, an in-plane, static tensile experiment was carried out to investigate the bearing performance of double-lap, single-bolt joints in X850 ± IM190 carbon fiber-reinforced polymer (CFRP) composites. The effects of ply ratio, 0° layers’ combination percentage, bolt diameter, and curing method were considered. Then, special attention was paid to determine the design parameters of X850 ± IM190 CFRP bolted joints, such as tensile strength of un-notched laminate and stress concentration relief factor. Based on these design parameters, an efficient semianalytical approach was established to obtain the ultimate bearing strength of the joints. The failure prediction exhibited excellent agreement with the experimental data. These results will play an important role in design and strength evaluation of X850 ± IM190 CFRP bolted joints.

Predicting the Young’s modulus of intercalated and exfoliated polymer/clay nanocomposites

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Vadoud Molajavadi ◽  
Hamid Garmabi
Keyword(s):  
Aspect Ratio ◽  
Young’S Modulus ◽  
Surface Area ◽  
High Aspect Ratio ◽  
Young's Modulus ◽  
Clay Nanocomposites ◽  
High Modulus ◽  
Proposed Model ◽  
Theoretical Predictions ◽  
New Equation

AbstractThe Halpin-Tsai equations were used for the composites with low level content of reinforcements, which contain lamellar shape, high modulus and high aspect ratio. These characteristics of reinforcements were taken into consideration to simplify the Halpin-Tsai equations. The effect of different parameters on the longitudinal Young’s modulus of well aligned polymer/clay nanocomposites was investigated for both exfoliated and intercalated microstructures. It was shown that the applied simplification had negligible effect on the prediction of the Halpin-Tsai model. For the intercalated structures with a high number of platelets per stack (n), increase in the gallery spacing did not influence the predicted modulus values. In an intercalated structure, the surface area of a stack, as the interface of fillermatrix, is n times lower than that of the exfoliated state. By considering the effect of the degree of exfoliation in the proposed model, a new equation was developed to predict the modulus enhancement in the nanocomposites filled with Montmorillonite (MMT). The theoretical predictions were supported by the experimental results.

A Spherical Model Calculation for Volumetric Response of Porous Rocks

1975 ◽  
Vol 42 (2) ◽  
pp. 363-368 ◽  
Author(s):  
J. J. Bhatt ◽  
M. M. Carroll ◽  
J. F. Schatz
Keyword(s):  
Experimental Data ◽  
Model Calculation ◽  
Hollow Sphere ◽  
Constitutive Relations ◽  
Applied Pressure ◽  
Spherical Model ◽  
Incompressible Material ◽  
Porous Rocks ◽  
Theoretical Predictions ◽  
Volumetric Response

The problem of external pressurization and release is solved for a hollow sphere of incompressible material obeying Coulomb’s law of failure. The resulting relations between the applied pressure and the porosity of the sphere are used in formulating constitutive relations for the volumetric response of porous rocks. The theoretical predictions are compared with experimental data for a sandstone and a tuff.

scholarly journals Experimental and Numerical Studies on Ballistic Laminates on the Polyethylene and Polypropylene Matrix

2017 ◽  
Vol 35 (02) ◽  
pp. 187-197 ◽  
Author(s):  
P. Mayer ◽  
D. Pyka ◽  
K. Jamroziak ◽  
J. Pach ◽  
M. Bocian
Keyword(s):  
Hybrid Composite ◽  
Material System ◽  
Aramid Fibers ◽  
Advantages And Disadvantages ◽  
Numerical Studies ◽  
Thermoplastic Matrix ◽  
Material Systems ◽  
New Material ◽  
Innovative Material ◽  
Polypropylene Matrix

ABSTRACTThe paper analyzes the issues relating to the applicability of innovative material systems for flexible composite armors. The authors made several samplings of aramid fibers (Kevlar 49) by replacing the epoxy resin base, which is often described in the literature, with the thermoplastic matrix - polyethylene (HDPE) and polypropylene (PP). The samples were fired with .38 Special Full Metal Jacketed (FMJ) ammunition produced by the S&B Company, and then the process of firing was modeled in the ABAQUS program. The advantages and disadvantages of the new material system including the possibility of its use in the construction of hybrid composite armors have been presented on the basis of the results of numerical analyses and ballistic tests.

scholarly journals Efficient Distortion Prediction of Additively Manufactured Parts Using Bayesian Model Transfer Between Material Systems

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Jack Francis ◽  
Arman Sabbaghi ◽  
M. Ravi Shankar ◽  
Morteza Ghasri-Khouzani ◽  
Linkan Bian
Keyword(s):  
Bayesian Model ◽  
Computation Time ◽  
Critical Issue ◽  
Material System ◽  
Element Analysis ◽  
Distortion Model ◽  
Material Systems ◽  
New Material ◽  
Model Transfer

Abstract Distortion in laser-based additive manufacturing (LBAM) is a critical issue that adversely affects the geometric integrity of additively manufactured parts and generally exhibits a complicated dependence on the underlying material. The differences in properties between distinct materials prevent the immediate application of a distortion model learned for one material to another, which introduces the challenge in LBAM of learning a distortion model for a new material system given past experiments. Current methods for investigating the distortion of different material systems typically involve finite element analysis or a large number of experiments in an empirical study. However, these methods do not learn from previous experiments and can incur significant costs in terms of computation, time, or resources. We propose a Bayesian model transfer methodology that is both physics-based and data-driven to leverage past experiments on previously studied material systems for more efficient distortion modeling of new systems. This method transfers distortion models across distinct materials based on the statistical effect equivalence framework by formulating the differences between two materials as a lurking variable. Our method reduces the experimentation and effort needed for specifying distortion models for new material systems. We validate our methodology in a case study of distortion model transfer from Ti–6Al–4V disks to 316L stainless steel disks. This case study is the first instance of model transfer between material systems and illustrates the ability of the Bayesian model transfer methodology to address the issue of comprehensive distortion modeling across varying material systems in LBAM.

Variational Principles for Non-Material Systems Within an Arbitrary Lagrangian Eulerian Description of Motion

2020 ◽  
Author(s):  
Giuseppe Pennisi ◽  
Olivier Bauchau
Keyword(s):  
Finite Element ◽  
Dynamic Behavior ◽  
Variational Principles ◽  
Material System ◽  
Arbitrary Lagrangian Eulerian ◽  
Complex Dynamic ◽  
Eulerian Description ◽  
Material Systems ◽  
Axially Moving ◽  
Dynamic Description

Abstract Dynamics of axially moving continua, such as beams, cables and strings, can be modeled by use of an Arbitrary La-grangian Eulerian (ALE) approach. Within a Finite Element framework, an ALE element is indeed a non-material system, i.e. a mass flow occurs at its boundaries. This article presents the dynamic description of such systems and highlights the peculiarities that arise when applying standard mechanical principles to non-material systems. Starting from D’Alembert’s principle, Hamilton’s principle and Lagrange’s equations for a non-material system are derived and the significance of the additional transport terms discussed. Subsequently, the numerical example of a length-changing beam is illustrated. Energetic considerations show the complex dynamic behavior non-material systems might exhibit.

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