Modeling the Effects of Texture on Thermal Expansion in Pressed PBX 9502 Components

2016 ◽  
Author(s):  
Miles A. Buechler ◽  
Nathan A. Miller ◽  
D. J. Luscher ◽  
Ricardo B. Schwarz ◽  
Darla Graff Thompson
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Texture Evolution ◽  
Thermal Strain ◽  
Element Model ◽  
Evolution Model ◽  
Component Level ◽  
Self Consistent ◽  
Orientation Distributions ◽  
Homogenization Scheme

This paper demonstrates the effects of texture induced during pressing of PBX 9502 charges. We quantify the spatially variable anisotropic thermal strains associated with preferred orientation of TATB crystallographic (002) poles within manufactured components. The modeling approach is based on a series of three models. First, a component-level finite element model of the charge during consolidation from powder into pressed explosives is used to predict the deformation associated with this process. The deformation predicted from these simulations is used with a texture evolution model to estimate orientation distributions for TATB crystals at every integration point within the HE charge. The orientation distributions estimated using the texture evolution model are used within a self-consistent homogenization scheme to predict the spatially-variable macroscopic or aggregate thermal strain as a function of temperature at every location within the pressed component. Results are compared with measurements of texture and anisotropic thermal expansion for several locations sampled from pressed explosive components.

Automotive Glass Exciter Technology for Acoustic Application

2014 ◽  
Author(s):  
Babak Ebrahimi ◽  
Amir Khajepour ◽  
Todd Deaville
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Experimental Studies ◽  
Element Model ◽  
Fe Model ◽  
Component Level ◽  
Modeling And Analysis ◽  
Electric Actuator ◽  
Conventional Systems ◽  
Fine Tune

This paper discusses the modeling and analysis of a novel audio subwoofer system for automotive applications using the automobile windshield glass. The use of a piezo-electric actuator coupled with a mechanical amplifier linked to a large glass panel provides a highly efficient method of producing sound. The proposed subwoofer system has the advantage over existing conventional systems of not only reducing the weight of the automobile, but also a significant power savings resulting in an increase of expected fuel economy. Among various design challenges, the glass-sealing design is of huge importance, as it affects the system dynamic response and so the output sound characteristics. The main goal in this manuscript is to evaluate different glass-sealing design configurations by providing a comprehensive Finite Element model of the system. To do so, a comprehensive, yet simplified FE model is developed, and experimental studies are performed in the component level to fine-tune and verify the model. Harmonic response of the system for each sealing configuration design is obtained in the frequency range of 0–200 Hz, and the results are compared and discussed. The finite element model is also beneficial in preliminary design of other components as well as the exciter placement, and predicting the performance of the overall system.

Component-Level Finite Element Model and Validation for a Modern American Football Helmet

2019 ◽  
Vol 5 (2) ◽  
pp. 117-131 ◽  
Author(s):  
M. C. Bustamante ◽  
D. Bruneau ◽  
J. B. Barker ◽  
D. Gierczycka ◽  
M. A. Coralles ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
American Football ◽  
Component Level ◽  
Football Helmet

A Real-Time Neural Network Estimator for Workpiece Thermal Expansion Errors

2000 ◽  
Author(s):  
A. D. Yoder ◽  
R. N. Smith
Keyword(s):  
Neural Network ◽  
Finite Element ◽  
Thermal Expansion ◽  
Finite Element Model ◽  
Real Time ◽  
Element Model ◽  
Precision Machining ◽  
Machining Processes ◽  
The Neural Network ◽  
The Finite Element Model

Abstract The importance of predicting and reducing thermal expansion errors in workpieces is becoming greater as better precision machining processes are developed. An artificial neural network model to estimate the workpiece thermal expansion errors in real-time during precision machining operations is developed and compared with experimental results. A finite element model of workpiece thermal expansion has been created to predict expansions in a thin cylinder undergoing a turning process. The neural network has been trained using finite element model solutions over a range of conditions to allow for changing machining parameters. To realize “on-line” capability, the measurable values of heat flux into the workpiece, surface heat transfer coefficient, and tool location are used as inputs and the expansion as the output for the neural network. The estimations of the network are compared with experimental results from a turning process on a large diameter aluminum cylinder. There is reasonable agreement between measured and estimated expansions with an average error of 18%. The neural network has not been trained at the cutting conditions used during the experiment. The speed of the neural network estimation is much greater than the solution to the finite element model. The finite element model required over 15 minutes to solve on a Pentium 133Mhz computer. The neural network calculated the expansions easily at 1 Hz during the experiment on the same computer. With real-time estimation using measurable data, compensation can be made in the tool path to correct for these errors. The application of this method to precision machining processes has the capability of greatly reducing the error caused by workpiece thermal expansions.

Thermal Analysis of a Ball-Screw System

2012 ◽  
Vol 591-593 ◽  
pp. 818-826 ◽  
Author(s):  
Chin Chung Wei ◽  
Jeng Haur Horng ◽  
Jen Fin Lin
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Finite Element Model ◽  
High Speed ◽  
Element Model ◽  
Surface Strain ◽  
Ball Screw ◽  
Control Factor ◽  
Positioning Error ◽  
Positioning Control

High speed ball-screw system has serious friction heat to form thermal expansion to each component. An analyzing model considering with contact deformation and thermal expansion is established in realizing positioning error for a high speed ball-screw system. A finite element model of nut is also built in calculating elongation of nut. Surface strain of nut is measured by strain gages in order to confirm with data obtained from finite element model. Temperature of nut and screw were also measured by thermal couples and are used in calculation of elongation by the use of linear elongation equation. The tendency of positioning error is well estimated by the analyzing model. The model can be used in feedback positioning control factor and develop precision high speed ball-screw system.

Design of a Composite Encapsulation for Concentrated Photovoltaic Systems With Improved Performance

2019 ◽  
Author(s):  
Kabeer Raza ◽  
Syed Sohail Akhtar ◽  
Abul Fazal M. Arif ◽  
Abbas Saeed Hakeem
Keyword(s):  
Thermal Conductivity ◽  
Finite Element ◽  
Thermal Expansion ◽  
Shear Modulus ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Material Design ◽  
Element Model ◽  
Parametric Studies

Abstract Most of the currently used encapsulants are inefficient for cooled concentrated photovoltaic (CPV) systems. The encapsulant of cells for CPV systems, must have an optimum combination of thermal conductivity, coefficient of thermal expansion and long term shear modulus. In this work an improved backside composite encapsulation is designed and developed that can provide increased power output and longer life by enhancing the effectiveness of cooling and reducing thermal stresses. The best combination of material properties is identified through parametric studies on finite element model of CPV laminate using ethylene vinyl acetate as datum line. It is found that increasing thermal conductivity from 0.311 to 0.75 W/mK can improve the cooling and hence the power production by 2%. While long term shear modulus and coefficient of thermal expansion needs to be reduced for a longer service life. Using in-house built material design codes, optimum combinations of matrix and filler were identified that could provide the set range of properties. In line with material design code, a total of only four samples using thermoplastic polyurethane as matrix and Al2O3 or AlN as fillers were synthesized to validate the design experimentally. The material properties were measured and used in the parent finite element model to evaluate the performance of the experimentally developed material and to validate the parametric studies. A good agreement is found between the experimental and computational results and hence the overall methodology is found effective for application focused design and development of composite materials. It is expected that this material design and development approach will provide a useful guideline to the CPV manufacturing industries.

Finite Element Analysis of Creep and Thermal Stress for Shape Memory Alloy Joint

2010 ◽  
Vol 452-453 ◽  
pp. 537-540 ◽  
Author(s):  
Xue Feng Zhou ◽  
You Hai Zhi ◽  
Bing Wang Gou
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Thermal Strain ◽  
Three Dimensional ◽  
Transient State ◽  
Element Model ◽  
Element Analysis ◽  
Joint System ◽  
Radial Temperature

The three-dimensional (3D) finite element model of shape memory alloy (SMA) joint system under a clamped-clamped support was established. Using the coupled thermal-mechanical transient state analysis, stress distributions of models under the different loads (internal pressure, temperature) were investigated. And the temperature field, thermal strain field, stress and creep of the joint system were obtained. The results show, 1) for the non-coat SMA joint system, the interface in middle region of the joint’s internal wall is the dangerous region. In this region, the joint’s adhesion failures easily occur and the crack easily initiate. The joint’s coat can improve the fatigue life of joint system. 2) There are higher levels of radial temperature gradient, temperature strain and temperature stress between the internal and external walls of the joint. The creep strain in the internal-external walls of the joint is the main reason for adhesion failure in middle interfaces between the joint and the pipe.

Stress Analysis of the Pressurized-Water Reactor Control Rod Under Operating Conditions

2020 ◽  
Author(s):  
Leo A. Carrilho
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Finite Element Model ◽  
Stress Analysis ◽  
Maximum Stress ◽  
Element Model ◽  
Operating Conditions ◽  
Pressurized Water ◽  
Control Rod ◽  
The Finite Element Model

Abstract This work aims to develop a finite element model of a PWR control rod at operating conditions for stress analysis of the rod cladding. The finite element model simulates a control rod exposed to high operating temperatures and pressure while portions of the rod are irradiated, resulting in accumulated fluence of neutrons by the rod materials. These high temperature and accumulated fluence induce thermal expansion and swelling of the rod materials, especially of the absorber, which may eventually interact with the rod cladding, generating stresses and strains in the wall of the cladding tube. Moreover, if the maximum stress or strain in the tube wall exceeds the design allowable limit, the absorber rod is considered failed. The author creates the control rod finite element model and apply the operating loads on two-dimensional axisymmetric elements to obtain displacements, temperatures, stresses, and strains. The model also includes contact surface elements to evaluate eventual mechanical interactions between absorber and cladding due to thermal expansion and swelling effects. This is a coupled nonlinear static analysis solution that includes thermal expansion effects to calculate temperature distribution and subsequent thermal strains in the absorber rod due to the heat generation rates and coolant temperature; swelling analysis to calculate absorber growth induced by irradiation; and creep analysis to calculate absorber stress relaxation under coolant pressure and temperature. The finite element model is capable of determining whether or not absorber-to-cladding gap closure will occur and if so, calculate maximum stress and strain in the rod cladding associated with mechanical interaction between the two components induced by the operating temperature and thermal fluence loads.

scholarly journals Correction to: Component-Level Finite Element Model and Validation for a Modern American Football Helmet

2019 ◽  
Vol 5 (2) ◽  
pp. 195-195
Author(s):  
M. C. Bustamante ◽  
D. Bruneau ◽  
J. B. Barker ◽  
D. Gierczycka ◽  
M. A. Corrales ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
American Football ◽  
Component Level ◽  
Football Helmet

Study on the Thermal Expansion Displacement during Spot Welding Depending on the Multi-Physical Coupling Finite Element Model

2014 ◽  
Vol 941-944 ◽  
pp. 2007-2011
Author(s):  
Cai Ping Liang ◽  
Yong Bing Li
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Finite Element Model ◽  
Spot Welding ◽  
Welding Process ◽  
Physical And Mechanical Properties ◽  
Element Model ◽  
Temperature Dependent ◽  
Monitoring And Forecasting

An incremental and thermal electro-mechanical coupled finite element model has been presented in this study for predicting spot nugget size, gap between workpieces, and thermal expansion displacement during spot welding process. Approximate temperature dependent material properties, including physical and mechanical properties, have been considered. The spot nugget shape and the thermal expansion displacement were obtained by simulation. The solutions showed that the displacement of workpieces was directly related to the quality of solder joints and can be as a monitoring parameter of spot weld quality. These calculations provide a theoretical reference for nugget quality monitoring and forecasting by electrode expansion displacements.

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