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Articles 1051 - 1080 of 1287
Full-Text Articles in Engineering
Empirical Modeling And Vision Based Control For Laser Aided Metal Deposition Process, Mallikharjuna R. Boddu, Srinivas Musti, Robert G. Landers, Sanjeev Agarwal, Frank W. Liou
Empirical Modeling And Vision Based Control For Laser Aided Metal Deposition Process, Mallikharjuna R. Boddu, Srinivas Musti, Robert G. Landers, Sanjeev Agarwal, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper gives a brief description of the laser aided manufacturing process. Empirical models describing the process dynamics of the laser aided metal deposition process is developed based on some of the models found in the literature. These models provide the basis for process planning and real time control. An embedded vision system, a two color temperature sensor, and a laser displacement sensor are incorporated for real time monitoring and control of the deposition process. The temperature profile of the surface and geometric characteristics of the melt pool are studied to ensure consistent operation of the process.
Research And Development Of A Hybrid Rapid Manufacturing Process, Frank W. Liou, J. Choi, Robert G. Landers, Vijayakumar Janardhan, S. N. Balakrishnan, Sanjeev Agarwal
Research And Development Of A Hybrid Rapid Manufacturing Process, Frank W. Liou, J. Choi, Robert G. Landers, Vijayakumar Janardhan, S. N. Balakrishnan, Sanjeev Agarwal
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper presents the research and development of a hybrid rapid manufacturing process being developed at the University of Missouri--Rolla. This process includes a laser deposition and a 5- axis CNC milling system. By combining laser deposition and machining processes, the resulting hybrid process can provide greater build capability and better accuracy and surface finish. The hybrid process can build some features that are difficult to build in using a purely deposition processes. The issues and related approaches in the research and development of the hybrid deposition-machining process, including laser deposition process, system design and integration, process planning, and sensor …
Skeleton-Based Geometric Reasoning For Adaptive Slicing In A Five-Axis Laser Aided Manufacturing Process System, Kunnayut Eiamsa-Ard, Jun Zhang, Frank W. Liou
Skeleton-Based Geometric Reasoning For Adaptive Slicing In A Five-Axis Laser Aided Manufacturing Process System, Kunnayut Eiamsa-Ard, Jun Zhang, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Multi-axis Laser Aided Manufacturing Process (LAMP) is an additive manufacturing process similar to laser cladding. This process can produce full functional parts [1]. Traditional Layered Manufacturing processes produce parts with limited surface quality; and also the build time is often long due to the deposition of sacrificial support structure. The multiple degrees of freedom endow the LAMP system a capability to build parts without support structure. An algorithm for adaptive slicing based on skeleton is presented in this paper. The skeleton is useful for many applications such as feature recognition, robot path planning, shape analysis, and etc [2]. The near …
Control Of Laser Cladding For Rapid Prototyping -- A Review, Mallikharjuna R. Boddu, Robert G. Landers, Frank W. Liou
Control Of Laser Cladding For Rapid Prototyping -- A Review, Mallikharjuna R. Boddu, Robert G. Landers, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Lasers have wide-ranging applications in the manufacturing field (e.g., cladding, welding, cutting, machining, drilling). Extensive work is being conducted to apply laser cladding as a Rapid Prototyping (RP) process. In this paper the authors illustrate various principles of laser cladding in rapid prototyping. Important process parameters for the control of the laser cladding process are discussed as well as the experimental methods adopted, and results obtained by, various authors.
Ingaasnsb/Gaas Quantum Wells For 1.55 Μm Lasers Grown By Molecular-Beam Epitaxy, Xiaodong Yang, J. B. Heroux, L. F. Mei, W. I. Wang
Ingaasnsb/Gaas Quantum Wells For 1.55 Μm Lasers Grown By Molecular-Beam Epitaxy, Xiaodong Yang, J. B. Heroux, L. F. Mei, W. I. Wang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
InGaAsNSb/GaAs quantum wells (QWs) were grown by solid-source molecular-beam epitaxy using a N2 radio frequency plasma source. The effect of adding Sb during growth of InGaAsN/GaAs QWs was studied. X-ray diffraction, reflection high-energy electron diffraction and transmission electron microscopy studies indicate that Sb suppresses the three-dimensional growth and improves the interface of the QWs. X-ray diffraction and secondary ion mass spectroscopy analysis show that Sb gets incorporated into the quantum well, which becomes a quinternary compound that was previously unexplored. The introduction of Sb during growth of InGaAsN/GaAs QWs significantly enhances the optical properties of the QWs. 1.53 /spl …
Membrane Electrostatic Precipitator, Hajrudin Pasic, M. Khairul Alam, David J. Bayless
Membrane Electrostatic Precipitator, Hajrudin Pasic, M. Khairul Alam, David J. Bayless
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A membrane is used as a collection substrate in an electrostatic precipitator (ESP). Possible material choices include fibers in the form of woven mats, screens made from stainless steel wires or fiber reinforced polymer composite membranes. The membranes have a tensile bias applied during operation, and have impulse tensile force applied during a dust removal step. By combining a dry ESP membrane field with wet-film cleaning field, it may be possible to improve collection efficiencies both by reducing turbulence and eliminating re-entrainment losses due to rapping. Through implementation of new materials that resist hostile ESP environments, the invention enhances the …
Network Formalism For Modeling Functionally Gradient Piezoelectric Plates And Stacks And Simulations Of Rainbow Ceramic Actuators, Robert W. Schwartz, A. Ballato, John Ballato
Network Formalism For Modeling Functionally Gradient Piezoelectric Plates And Stacks And Simulations Of Rainbow Ceramic Actuators, Robert W. Schwartz, A. Ballato, John Ballato
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A simple network representation is given for a stack of thin, homogeneous piezoelectric plates, executing a single thickness mode of motion. All plates may differ in thickness and material properties, including dielectric loss, ohmic conductivity, and viscous loss. Each plate is driven by a thickness-directed electric field, and all stack elements are connected electrically in series. Functionally gradient single plates and composites are readily modeled by the network, to a desired precision, using a sequence of circuit elements representing stepwise variations in material properties and layer thicknesses. Simulations of RAINBOW (reduced and internally biased oxide wafer) ceramics are given.
Robust State Dependent Riccati Equation Based Guidance Laws, S. N. Balakrishnan, Ming Xin
Robust State Dependent Riccati Equation Based Guidance Laws, S. N. Balakrishnan, Ming Xin
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A robust state dependent Riccati equation based guidance/control is investigated in this study. In order to have a better design tool in terms of required interceptor accelerations, the target intercept geometry is formulated in a set of polar coordinates. With this formulation, we formulate a cost function with state dependent weights. In this study, we investigate the effects of such cost functions on the levels of interceptor accelerations. We also synthesize a neural network based extra controller to achieve the robustness in the presence of the target acceleration. In this manner, we will not need target acceleration estimation explicitly in …
An Optimal Control Based Treatment Strategy For Parturient Paresis Using Neural Networks, Radhakant Padhi, S. N. Balakrishnan
An Optimal Control Based Treatment Strategy For Parturient Paresis Using Neural Networks, Radhakant Padhi, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
An optimal online feedback treatment strategy is developed for the parturient paresis of cows, based on nonlinear optimal control theory. A limitation in the development of an existing mathematical model for calcium homeostasis is addressed and the model is extended to incorporate control inputs. An optimal feedback controller is synthesized for the nonlinear system using neural networks. Though the main aim of this paper is to solve the biomedical control problem, the methodology presented in this paper is a general computational tool, which can be applied to solve a fairly general class nonlinear optimal control problems.
Robust State Dependent Riccati Equation Based Robot Manipulator Control, Ming Xin, S. N. Balakrishnan, Zhongwu Huang
Robust State Dependent Riccati Equation Based Robot Manipulator Control, Ming Xin, S. N. Balakrishnan, Zhongwu Huang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We present a new optimal control approach to robust control of robot manipulators in the framework of state dependent Riccati equation (SDRE) technique. To treat this highly nonlinear control system, we formulate it as a nonlinear optimal regulator problem. SDRE technique was used to synthesize an optimal controller to this class of robot control problem. We also synthesize a neural network based extra controller to achieve the robustness in the presence of the parameter uncertainties. A typical two-link robot position control problem was studied to show the effectiveness of SDRE approach and robust extra control design to robotic application.
Re-Examination Of The Crypto-Steady Pressure-Exchanger (Virtual Turbomachine), T. Scott, David W. Riggins
Re-Examination Of The Crypto-Steady Pressure-Exchanger (Virtual Turbomachine), T. Scott, David W. Riggins
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A crypto-steady pressure-exchanger (rotating center body ejecting fluid in a supersonic flow field) is investigated based on fundamental fluid dynamic principles. The results are then compared to computational fluid dynamic (CFD) simulations of a simplified device. On the basis of this comparison the device studied is correctly classified as an unsteady ejector instead of a type of turbomachinery. Entropy gains (total pressure losses) associated with the complex fluid-fluid and fluid-center body interactions are shown to be greater than total pressure gains due to work addition. Compared to a steady ejector, the virtual turbomachine shows increased entrainment (mixing) of the main …
A Numerical Study Of Automotive Gas Tank Filler Pipe Two Phase Flow, R. Banerjee, Kakkattukuzhy M. Isaac, L. Oliver, W. Breig
A Numerical Study Of Automotive Gas Tank Filler Pipe Two Phase Flow, R. Banerjee, Kakkattukuzhy M. Isaac, L. Oliver, W. Breig
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Automotive refueling is gaining greater importance because fuel vapors released during refueling are believed to increase ozone levels in urban areas. As a step towards On-Board Refueling Vapor Recovery (ORVR) designs, vapor generation and transport during refueling needs to be understood to develop recovery techniques. The objective of the present study is to understand the fluid flow inside the automotive gas tank filler pipe using commercially available Computational Fluid Dynamics (CFD) software. This effort is expected to yield detailed flow field information, including air entrainment. The phenomena of well-back, the process of fuel flooding the filler pipe and flowing backwards …
Dynamics Of Poly(Vinyl Acetate)-D₃ On Silica, Robert D. O'Connor, Frank D. Blum, Gu Xu
Dynamics Of Poly(Vinyl Acetate)-D₃ On Silica, Robert D. O'Connor, Frank D. Blum, Gu Xu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Poly(vinyl acetate) (PVAc) is an important polymer in applications because of both its bulk and surface characteristics. Its chain architecture gives it a low Tg and, generally, good qualities for processing and applications, which include paints, adhesives, thin films and surface coatings. In this study, we investigate the surface dynamics of PVAc absorbed onto silica with deuterium nuclear magnetic resonance (2H NMR). For dynamics studies, 2H NMR is an excellent technique because it uses an innocuous probe that can report on correlation times (τc) from approximately 10-8 s to 10 s. We report the use of two-dimensional exchange NMR (2D-X) …
Robust Adaptive Critic Based Neurocontrollers For Missiles With Model Uncertainties, Zhongwu Huang, S. N. Balakrishnan
Robust Adaptive Critic Based Neurocontrollers For Missiles With Model Uncertainties, Zhongwu Huang, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A Lyapunov theory-based controller is proposed in this paper for robustness against model uncertainties in the control of a missile. The controller design consists of two parts; in the first phase, an optimal nonlinear controller is designed with neural networks for tracking. This is based on the adaptive critic method that consists of one neural network called the supervisor or critic and a second network called an action network or a controller. Each network is trained through the output of the other network and equations related to optimal control. When their outputs are mutually consistent, the controller network output is …
Amplitude Modulated Droplet Formation In High Precision Solder Droplet Printing, Qingbin Liu, M. Orme, Ming-Chuan Leu
Amplitude Modulated Droplet Formation In High Precision Solder Droplet Printing, Qingbin Liu, M. Orme, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
There are many methods used at present to apply solder to wafers, ceramics, laminate and flex circuit boards, and other substrates. Among these, high-precision solder droplet printing technology, which is noncontact, data driven, flexible and environmentally friendly, is a key enabling technology. This technology selectively deposits solder droplets only where required, and therefore needs no mask or secondary resist removal, uses materials more efficiently and creates less waste than other methods. Currently, continuous droplet formation from capillary streams is mainly achieved by application of the well-known Rayleigh instability in which a sinusoidal disturbance is applied to the stream, resulting in …
Development Of Transparent Lsco And Lscno Conductors For Optical Shutter Systems, Robert W. Schwartz, M. T. Sebastian, M. Charoenwongsa, H. D. Dobberstein
Development Of Transparent Lsco And Lscno Conductors For Optical Shutter Systems, Robert W. Schwartz, M. T. Sebastian, M. Charoenwongsa, H. D. Dobberstein
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We have prepared lanthanum strontium cobalt oxide (La0.50Sr0.50CoO3; LSCO 50/50) and lanthanum strontium cobalt nickel oxide (La0.50Sr0.50Co0.50Ni0.50O3; LSCNO) as candidate transparent electrodes for use in a shutter-based infrared sensor protection device. The shutter device requires that the electrode be transparent (80% transmission) and have moderate sheet resistance (300 Ω/sq.). Because of the effects of film thickness on intrinsic material properties, such as resistivity and extinction coefficient, and simple engineering issues (i.e., the relationship between film thickness, resistance and transmission), films of various thicknesses were prepared to achieve an optimal balance of electrical and optical performance. van der Pauw measurements and …
Adaptive Critic Based Neuro-Observer, Xin Liu, S. N. Balakrishnan
Adaptive Critic Based Neuro-Observer, Xin Liu, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A new Neural Network (NN) based observer design method for nonlinear systems represented by nonlinear dynamics and linear/nonlinear measurement is proposed in this paper. In this new approach, as the first step, the observer design problem is changed into a "controller" design problem by establishing the error dynamics, and then the Adaptive Critic (AC) based approach is applied on this error dynamics to design a 'controller', such that the errors are driven to zero. The resulting observer has inherent robustness from the AC based design approach. Some simulations are presented to illustrate the effectiveness of this approach.
High Precision Solder Droplet Printing Technology: Principle And Applications, Qingbin Liu, M. Orme, Ming-Chuan Leu
High Precision Solder Droplet Printing Technology: Principle And Applications, Qingbin Liu, M. Orme, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Solder droplet printing technology, which is low-cost, noncontact, flexible, data-driven, and environmentally friendly, has emerged as an enabling technology for precisely placing fine solder deposits on a variety of small substrates. It is suitable for a variety of applications including direct chip attach site preparation, 3D substrates, fine line interconnect, substrate via fill, optoelectronics and many others. It enables manufacturing techniques that are impossible or unfeasible with current technology, such as localized replacement of solder on board, depositing solder in different thicknesses on the same board, or using more than one type of solder on the same board. This makes …
Study On Water Deposit In Rapid Freeze Prototyping Process, Guanghua Sui, Weihan Zhang, Ming-Chuan Leu
Study On Water Deposit In Rapid Freeze Prototyping Process, Guanghua Sui, Weihan Zhang, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Rapid Freeze Prototyping (RFP) builds a three-dimensional ice part according to its CAD model by depositing and rapidly freezing water in a layer-by-layer manner. To study the water deposit in RFP, assumptions are made based on the deformation of water droplet impinging on a flat substrate, the thermal analysis of a new layer of water deposit, and the characteristics of solidification of a water drop. The equations governing the cross-sectional profile of the water deposit are then established. A model of water deposit is proposed by simplifying the equations under our experimental conditions in RFP. By using this model, equations …
Investment Casting With Ice Patterns Made By Rapid Freeze Prototyping, Wei Zhang, Ming-Chuan Leu, Chao Feng, Rong Ren, Renjie Zhang, Qingping Lu, Jubu Jiang, Yongnian Yan
Investment Casting With Ice Patterns Made By Rapid Freeze Prototyping, Wei Zhang, Ming-Chuan Leu, Chao Feng, Rong Ren, Renjie Zhang, Qingping Lu, Jubu Jiang, Yongnian Yan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
One of the most promising applications of rapid freeze prototyping (RFP) is making metal parts by investment casting with the built ice parts. The integration of RFP and investment casting allows fast creation of complex net-shape metal parts directly from their CAD models. The advantages of doing so include no part geometric complexity limitation, no experience of parting line design and assembling needed, clean and low-cost of process operation, and good performance. In this paper, we will present our recent study on binder selection, slurry making, ceramic shell making, and the casting results of the metal parts.
Determination And Improvement Of Building Speed In Rapid Freeze Prototyping, Wei Zhang, Guanghua Sui, Ming-Chuan Leu
Determination And Improvement Of Building Speed In Rapid Freeze Prototyping, Wei Zhang, Guanghua Sui, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Rapid freeze prototyping (RFP) is a solid freeform fabrication process that builds an ice part by rapidly freezing water in a layer by layer manner. One advantage of this process is the ability to build ice parts faster than other SFF processes. The factors that affect the speed of contour building and interior filling in RFP are identified. The influence of these factors is analyzed through heat transfer and material flow analyses. A model based on heat transfer analysis is proposed to determine the maximum achievable speed of contour building under stable conditions. Experiments are conducted to validate the performance …
Laser Additive Manufacturing Process Planning And Automation, Jun Zhang, Jianzhong Ruan, Frank W. Liou
Laser Additive Manufacturing Process Planning And Automation, Jun Zhang, Jianzhong Ruan, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper presents a Laser Additive Manufacturing Process Planning (LAMPP) being developed at the University of Missouri-Rolla. The off-line planning recognizes difficult-to-build features from an STL file, selects optimal part orientation and building directions based on the skeleton information of the object geometry, and optimizes the sub-process sequences for deposition and machining. During the optimization of the subpart building processes, collaboration between the deposition process planner and the machining process planner is needed to check the deposition availability and machinability. As a result, tool paths for both the laser head and the machining head are automatically generated.
High-Temperature Characteristics Of 1.3 Μm Ingaasn:Sb/Gaas Multiple-Quantum-Well Lasers Grown By Molecular-Beam Epitaxy, Xiaodong Yang, J. B. Heroux, M. J. Jurkovic, W. I. Wang
High-Temperature Characteristics Of 1.3 Μm Ingaasn:Sb/Gaas Multiple-Quantum-Well Lasers Grown By Molecular-Beam Epitaxy, Xiaodong Yang, J. B. Heroux, M. J. Jurkovic, W. I. Wang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
1.3 μm InGaAsN:Sb/GaAs multiple-quantum-well laser diodes have been grown by solid-source molecular-beam epitaxy using Sb as a surfactant. A low threshold of 1.1 kA/cm² was achieved for broad-area laser diodes under pulsed operation at room temperature. High-temperature device characterization revealed characteristic temperatures (T₀) of 92 and 54 K for operating temperatures below and above 75°C, respectively, as well as a lasing-wavelength temperature dependence of 0.36 nm/°C.
Evaluation Of Lsco Electrodes For Sensor Protection Devices, Robert W. Schwartz, M. T. Sebastian
Evaluation Of Lsco Electrodes For Sensor Protection Devices, Robert W. Schwartz, M. T. Sebastian
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We have evaluated lanthanum strontium cobalt oxide (La0.50Sr0.50CoOx; LSCO 50/50) as a candidate “transparent” electrode for use in an electrostatic shutter-based infrared sensor protection device. The device requires that the electrode be transparent (80% transmission) and have moderate sheet resistance (300 - 500 Ω/sq.). To meet these needs, the effects of postdeposition annealing on the resistivity and optical absorption characteristics of sputter deposited LSCO thin films were studied. The as-deposited films were characterized by an absorption coefficient of ~ 12,500 cm-1 and resistivities of ~ 0.08 to 0.5 Ω-cm. With annealing at 800°C, the resistivity decreased to 350 μΩ-cm, while …
Convergence Analysis Of Adaptive Critic Based Optimal Control, S. N. Balakrishnan, Xin Liu
Convergence Analysis Of Adaptive Critic Based Optimal Control, S. N. Balakrishnan, Xin Liu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Adaptive critic based neural networks have been found to be powerful tools in solving various optimal control problems. The adaptive critic approach consists of two neural networks which output the control values and the Lagrangian multipliers associated with optimal control. These networks are trained successively and when the outputs of the two networks are mutually consistent and satisfy the differential constraints, the controller network output produces optimal control. In this paper, we analyze the mechanics of convergence of the network solutions. We establish the necessary conditions for the network solutions to converge and show that the converged solution is optimal.
Lifecycle Analysis For Environmentally Conscious Solid Freeform Manufacturing, Yanchun Luo, Ji Zhiming, Ming-Chuan Leu, R. J. Caudill
Lifecycle Analysis For Environmentally Conscious Solid Freeform Manufacturing, Yanchun Luo, Ji Zhiming, Ming-Chuan Leu, R. J. Caudill
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A lifecycle based process model for analyzing the environmental performance of SFM processes and SFM based rapid tooling processes is presented in this paper. The process environmental performance assessment model considers material, energy and disposal scenarios. The material use, process parameters (e.g. scanning speed) and power use can affect the environmental consequence of a process when material resource, energy, human health and environmental damage are taken into account. The presented method is applied to the SLA process and two SLA based rapid tooling processes. The method can be used to compare different rapid prototyping (RP) and RT processes in terms …
Robust Adaptive Critic Based Neurocontrollers For Systems With Input Uncertainties, S. N. Balakrishnan, Zhongwu Huang
Robust Adaptive Critic Based Neurocontrollers For Systems With Input Uncertainties, S. N. Balakrishnan, Zhongwu Huang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A two-neural network approach to solving optimal control problems is described in this study. This approach called the adaptive critic method consists of two neural networks: one is called the supervisor or critic, and the other is called an action network or controller. The inputs to both these networks are the current states of the system to be controlled. Each network is trained through an output of the other network and the conditions for optimal control. When their outputs are mutually consistent, the controller network output is optimal. The optimality is limited to the underlying model. Hence, we develop a …
Midcourse Guidance Law With Neural Networks, Dongchen Han, S. N. Balakrishnan
Midcourse Guidance Law With Neural Networks, Dongchen Han, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A neural network-based synthesis of an optimal midcourse guidance law is presented in this study. We use a set of two-neural networks; the first network called 'a critic' outputs the Lagrange's multipliers arising in an optimal control formulation and second network called 'an action network' outputs the optimal guidance/control. In this so-called 'adaptive critic' approach, the inputs to the networks are the current values of the states. This approach needs no external training. System equations, optimality conditions and the costate equations are used in conjunction with the network outputs to provide the targets for the neural networks. When the critic …
Editorial, Ahmed Noor, Victor Birman
Editorial, Ahmed Noor, Victor Birman
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Experimental Characterization Of Hygrothermal And Aging Effects In Textile Composites, Lokeswarappa R. Dharani, Samit Roy, V. Gupta, Weiqun Xu, N. Dixon
Experimental Characterization Of Hygrothermal And Aging Effects In Textile Composites, Lokeswarappa R. Dharani, Samit Roy, V. Gupta, Weiqun Xu, N. Dixon
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper summarizes the hygrothermal and physical aging tests that were conducted on AS4/PR500 5HS textile composite laminates. The objectives of the hygrothermal tests were to determine the diffusivity and maximum moisture content of the laminate. Three temperatures and three relative humidity levels (RH) were used in combination to create seven test conditions. In addition, three stress levels and three damage levels were imposed to examine the combined effects of stress and damage on moisture absorption. Short-term creep tests were performed on neat resin at different test temperatures to characterize physical aging of the resin matrix. In addition, creep and …