Archive for June, 2007
tugas elmes 2
June 20th, 2007
17.42
akhirnya.. stelah berjuang selama 1 semester dalam tugas elmes yang super duper parah ini, kami berhasil menyelesaikannya! yippi!
semoga tugas elems yang kami buat ini bisa menyumbangkan sesuatu yang berarti buat negeri ini. amiin..
nantikan foto-foto kami!! =)
"jadilah sesuatu yang bermanfaat bagi dunia.."
title: Robust control design of remote catheter insertion mechanism with haptic feedback authors: Kothari, Chintan Govindbhai
abstract: Robotic surgery is becoming a popular technique for certain procedures since benefits of minimally invasive surgery (MIS) have become general knowledge. However, one of the major shortcomings of the present generation of master-slave robotic systems is the lack of haptic feedback; the surgeon that remotely controls the robot is not able to feel what is happening inside the patient. The objective of this thesis was to design a robust control system for a catheter insertion mechanism for cardiac catheterization with haptic feedback. This thesis is divided into two parts. The first part covers a comprehensive literature review, laboratory setup design and implementation. The second part covers the control aspect and design of a robust control. An H∞controller was used to achieve system robustness. A new approach to find teleoperation system model for H∞ controller is given. The designed controller was implemented in MATLAB.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
abstract: Robotic surgery is becoming a popular technique for certain procedures since benefits of minimally invasive surgery (MIS) have become general knowledge. However, one of the major shortcomings of the present generation of master-slave robotic systems is the lack of haptic feedback; the surgeon that remotely controls the robot is not able to feel what is happening inside the patient. The objective of this thesis was to design a robust control system for a catheter insertion mechanism for cardiac catheterization with haptic feedback. This thesis is divided into two parts. The first part covers a comprehensive literature review, laboratory setup design and implementation. The second part covers the control aspect and design of a robust control. An H∞controller was used to achieve system robustness. A new approach to find teleoperation system model for H∞ controller is given. The designed controller was implemented in MATLAB.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
Rollover and roof crush analysis of low-floor mass transit bus
June 15th, 2007
title: Rollover and roof crush analysis of low-floor mass transit bus authors: Deshmukh, Pankaj S.
abstract: Today transit buses are an integral part of the national transportation system. According to National Transportation Statistics from 1990 to 2002, the number of transit motor buses in the U.S. has increased 30 percent. Although buses are one of the safest means of transportation, occupant injuries and fatalities in bus crashes do occur. Rollover strength has become an important issue for bus and coach manufacturers. Today European regulation “ECE-R66” is in force to prevent catastrophic rollover accidents. The Standard Bus Procurement Guidelines (SBPG) of the American Public Transit Association (APTA) also mentions the roof crush test for the assessment of bus superstructure and roof. This thesis discusses the development of a finite element (FE) model of a bus, and the analysis of its roof crush and rollover in LS-DYNA. The FE model was validated for the roof crush test carried according to the standard bus procurement guidelines (SBPG). ADAMS-View software was used to simulate the rollover of the bus. Bus accelerations, velocities, and its angle with the ground just before impact were measured in ADAMS and then used as input for the LSDYNA analysis. According to the ECE-R66 regulation, a passenger’s survival space is defined in the bus model to check whether there is any intrusion into the survival space during or after the rollover. This ensures that the bus structure has sufficient strength to avoid intrusions into the survival space. The effect of passengers’ weight on energy absorbed by the bus structures during rollover is also discussed. Development of the MADYMO bus model and its rollover simulations were also included in this research. Dummy kinematics and injuries sustained during rollover for various seated and standing positions were studied as well.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
abstract: Today transit buses are an integral part of the national transportation system. According to National Transportation Statistics from 1990 to 2002, the number of transit motor buses in the U.S. has increased 30 percent. Although buses are one of the safest means of transportation, occupant injuries and fatalities in bus crashes do occur. Rollover strength has become an important issue for bus and coach manufacturers. Today European regulation “ECE-R66” is in force to prevent catastrophic rollover accidents. The Standard Bus Procurement Guidelines (SBPG) of the American Public Transit Association (APTA) also mentions the roof crush test for the assessment of bus superstructure and roof. This thesis discusses the development of a finite element (FE) model of a bus, and the analysis of its roof crush and rollover in LS-DYNA. The FE model was validated for the roof crush test carried according to the standard bus procurement guidelines (SBPG). ADAMS-View software was used to simulate the rollover of the bus. Bus accelerations, velocities, and its angle with the ground just before impact were measured in ADAMS and then used as input for the LSDYNA analysis. According to the ECE-R66 regulation, a passenger’s survival space is defined in the bus model to check whether there is any intrusion into the survival space during or after the rollover. This ensures that the bus structure has sufficient strength to avoid intrusions into the survival space. The effect of passengers’ weight on energy absorbed by the bus structures during rollover is also discussed. Development of the MADYMO bus model and its rollover simulations were also included in this research. Dummy kinematics and injuries sustained during rollover for various seated and standing positions were studied as well.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
Analytical modeling of metallic honeycomb for energy absorption and validation with FEA
June 15th, 2007
title: Analytical modeling of metallic honeycomb for energy absorption and validation with FEA authors: Jeyasingh, Vinoj Meshach Aaron
abstract: Honeycomb materials possess high energy absorption characteristics and are useful for the impact protection of structural members. Various honeycomb configurations are being developed for a variety of applications. Analytical models are now available to determine the energy absorption characteristics of the regular hexagonal type of honeycomb. However, the development a parameterized analytical model that can determine the energy absorption characteristics of various honeycomb shapes is needed. In this research, a parameterized analytical model is developed for the typical honeycomb shape, and is validated using experimental and finite element analysis. Honeycomb materials exhibit strain-rate effects at impact velocities. They can have higher energy absorption during dynamic crush than during quasi-static crush. In order to determine the energy absorption of honeycomb material at higher velocity, the characterization of it must be made using high-impact testing machines, which are expensive and time-consuming. Therefore, development of an analytical model that can predict energy absorption at higher velocities is needed. Also, strain-rate coefficients must be determined for each particular type of honeycomb since the strain rate depends on the geometrical properties of the honeycomb. Therefore, strain-rate coefficients were developed for each honeycomb model in this research. The energy absorption of honeycombs at higher impact velocities was also determined using the low-velocity test, which will be useful when only low-velocity machines are available for testing honeycombs. Finally, a performance analysis was carried out using response surface methods to maximize energy absorption of the honeycomb.
description: Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
abstract: Honeycomb materials possess high energy absorption characteristics and are useful for the impact protection of structural members. Various honeycomb configurations are being developed for a variety of applications. Analytical models are now available to determine the energy absorption characteristics of the regular hexagonal type of honeycomb. However, the development a parameterized analytical model that can determine the energy absorption characteristics of various honeycomb shapes is needed. In this research, a parameterized analytical model is developed for the typical honeycomb shape, and is validated using experimental and finite element analysis. Honeycomb materials exhibit strain-rate effects at impact velocities. They can have higher energy absorption during dynamic crush than during quasi-static crush. In order to determine the energy absorption of honeycomb material at higher velocity, the characterization of it must be made using high-impact testing machines, which are expensive and time-consuming. Therefore, development of an analytical model that can predict energy absorption at higher velocities is needed. Also, strain-rate coefficients must be determined for each particular type of honeycomb since the strain rate depends on the geometrical properties of the honeycomb. Therefore, strain-rate coefficients were developed for each honeycomb model in this research. The energy absorption of honeycombs at higher impact velocities was also determined using the low-velocity test, which will be useful when only low-velocity machines are available for testing honeycombs. Finally, a performance analysis was carried out using response surface methods to maximize energy absorption of the honeycomb.
description: Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
Finite element analysis of vertebral end-plate failure under high dynamic axial load and its relation to age
June 15th, 2007
title: Finite element analysis of vertebral end-plate failure under high dynamic axial load and its relation to age authors: Kalyanrao, Thorbole Chandrashekhar
abstract: This research was aimed to develop the analytical model of functional spinal unit with the intent of understanding the contribution of intervertebral disc condition on the failure mechanism of end-plates under high rate dynamic loading. The condition of the disc for young people is healthy as compared to old person. The simple single degree of freedom DRI (Dynamic response Index) model was utilized to measure the spinal deflection under the influence of dynamic loading is incapable of estimating the potential injury due to disc swelling. The failure considered is always the vertebral body failure due to crushing, but in reality, condition of disc plays important role in deciding the failure of the vertebrae. The detailed axis-symmetry model was utilized to understand the effect of various factors on the end-plate failure mechanism and it is observed that deflection of the end plate is critical failure criteria. The age and the peak load were found to be the significant factors dictating end-plate failure. In young people the deflection of end plate was higher as compared to the old people due to hydrated disc capable of swelling under dynamic loads. The simplified three dimensional model of vertebral motion segment L2-L3 was developed in order to understand the effect of nucleus pulpous pressure in end-plate deflection and to incorporate this model into the DRI model in order to estimate the effect of dynamic loading on the resulting spinal injury. The three dimensional model utilizes the MADYMO material models. The relaxation modulus for the nucleus and the annulus are obtained from the published results and the material parameters were mapped from these published data. Results of a sensitivity analysis indicated the major contribution of age on the end-plate failure. The result clearly indicated the need of modifying the present way of modeling the nucleus as incompressible fluid to viscoelastic incompressible fluid. This study indicated that failure of the end-plate was an important link in the failure mechanism of the spinal unit; this failure lead to the transmission of the disc tissue into the vertebrae and caused the burst fracture.
description: Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
abstract: This research was aimed to develop the analytical model of functional spinal unit with the intent of understanding the contribution of intervertebral disc condition on the failure mechanism of end-plates under high rate dynamic loading. The condition of the disc for young people is healthy as compared to old person. The simple single degree of freedom DRI (Dynamic response Index) model was utilized to measure the spinal deflection under the influence of dynamic loading is incapable of estimating the potential injury due to disc swelling. The failure considered is always the vertebral body failure due to crushing, but in reality, condition of disc plays important role in deciding the failure of the vertebrae. The detailed axis-symmetry model was utilized to understand the effect of various factors on the end-plate failure mechanism and it is observed that deflection of the end plate is critical failure criteria. The age and the peak load were found to be the significant factors dictating end-plate failure. In young people the deflection of end plate was higher as compared to the old people due to hydrated disc capable of swelling under dynamic loads. The simplified three dimensional model of vertebral motion segment L2-L3 was developed in order to understand the effect of nucleus pulpous pressure in end-plate deflection and to incorporate this model into the DRI model in order to estimate the effect of dynamic loading on the resulting spinal injury. The three dimensional model utilizes the MADYMO material models. The relaxation modulus for the nucleus and the annulus are obtained from the published results and the material parameters were mapped from these published data. Results of a sensitivity analysis indicated the major contribution of age on the end-plate failure. The result clearly indicated the need of modifying the present way of modeling the nucleus as incompressible fluid to viscoelastic incompressible fluid. This study indicated that failure of the end-plate was an important link in the failure mechanism of the spinal unit; this failure lead to the transmission of the disc tissue into the vertebrae and caused the burst fracture.
description: Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
Finite element modeling of low floor mass transit bus and analysis of frontal impact scenarios
June 15th, 2007
title: Finite element modeling of low floor mass transit bus and analysis of frontal impact scenarios authors: Joshi, Aditya Umakant
abstract: There is no international regulation for the frontal collision of the buses, protecting their occupants and partners in traffic. There are some regulation such as ECE R-80 which deals with strength of seat structure of the coaches and their anchorages strength. There is increasing need to focus issues like occupant protection and full scale crash testing regulation for buses. This thesis attempts to collect possible subjects required for international regulation required for crashworthiness of transit buses. This research attempts to develop and validate a model of transit bus for all three impact conditions. The full finite element model is developed with help hypermesh software and its validation and analysis is done with help Ls-Dyna nonlinear finite element solver. The cost of actual testing and secrecy maintained by manufacturers make research process difficult and increase the importance of computer simulations. To boost the research of crash worthiness of transit need for computer model is felt. This thesis examines several frontal crash test procedures and evaluates how well each procedure meets the objective. This validated model is used to analyze various real world impact scenarios and its analysis with European and federal regulation. This validated model is used to extract crash pulses of various impact scenarios at the center of gravity of the bus. These extracted crash pulses are applied to the madymo model to estimate the injuries to occupants of the bus. This thesis discusses the design aspects of bus frontal impact behavior as one of the main subjects of bus crashworthiness and results of previous full scale tests comparing the Fem simulation results carried out on the transit bus.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
abstract: There is no international regulation for the frontal collision of the buses, protecting their occupants and partners in traffic. There are some regulation such as ECE R-80 which deals with strength of seat structure of the coaches and their anchorages strength. There is increasing need to focus issues like occupant protection and full scale crash testing regulation for buses. This thesis attempts to collect possible subjects required for international regulation required for crashworthiness of transit buses. This research attempts to develop and validate a model of transit bus for all three impact conditions. The full finite element model is developed with help hypermesh software and its validation and analysis is done with help Ls-Dyna nonlinear finite element solver. The cost of actual testing and secrecy maintained by manufacturers make research process difficult and increase the importance of computer simulations. To boost the research of crash worthiness of transit need for computer model is felt. This thesis examines several frontal crash test procedures and evaluates how well each procedure meets the objective. This validated model is used to analyze various real world impact scenarios and its analysis with European and federal regulation. This validated model is used to extract crash pulses of various impact scenarios at the center of gravity of the bus. These extracted crash pulses are applied to the madymo model to estimate the injuries to occupants of the bus. This thesis discusses the design aspects of bus frontal impact behavior as one of the main subjects of bus crashworthiness and results of previous full scale tests comparing the Fem simulation results carried out on the transit bus.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
Evaluation of post-weld heat treatments for corrosion protection in friction stir welded 2024 and 7075 aluminum alloys
June 15th, 2007
title: Evaluation of post-weld heat treatments for corrosion protection in friction stir welded 2024 and 7075 aluminum alloys authors: Widener, Christian Aragon
abstract: This dissertation presents the results of an investigation into the corrosion resistance of friction stir welding (FSW) for aerospace structures. Two of the most common aerospace aluminum alloys, 2024 and 7075, were investigated. In the as-welded condition, both alloys were found to be highly susceptible to exfoliation corrosion, and 7075 was found to be susceptible to stress corrosion cracking as well. The goal of this research was to identify proper initial temper selection and postweld aging treatments for enhancing the corrosion resistance of both 2024 and 7075 alloys, and their dissimilar joints. A large number of heat treatments were investigated for 7075 in the T6 and T73 tempers, including retrogression re-aging (RRA). Heat treatments were also investigated for 2024-T3 and 2024-T81. Samples were evaluated for resistance to exfoliation corrosion using optical microscopy. Microhardness, electrical conductivity, tension, and fatigue crack propagation tests were also performed on the samples. Beneficial heat treatments were found for both alloys as well as for their dissimilar joints.
description: College of Engineering, Dept. of Mechanical Engineering. "December 2005." Includes biblliographic references (192-203 leaves)
abstract: This dissertation presents the results of an investigation into the corrosion resistance of friction stir welding (FSW) for aerospace structures. Two of the most common aerospace aluminum alloys, 2024 and 7075, were investigated. In the as-welded condition, both alloys were found to be highly susceptible to exfoliation corrosion, and 7075 was found to be susceptible to stress corrosion cracking as well. The goal of this research was to identify proper initial temper selection and postweld aging treatments for enhancing the corrosion resistance of both 2024 and 7075 alloys, and their dissimilar joints. A large number of heat treatments were investigated for 7075 in the T6 and T73 tempers, including retrogression re-aging (RRA). Heat treatments were also investigated for 2024-T3 and 2024-T81. Samples were evaluated for resistance to exfoliation corrosion using optical microscopy. Microhardness, electrical conductivity, tension, and fatigue crack propagation tests were also performed on the samples. Beneficial heat treatments were found for both alloys as well as for their dissimilar joints.
description: College of Engineering, Dept. of Mechanical Engineering. "December 2005." Includes biblliographic references (192-203 leaves)
Comparison of structural damage and occupant injuries corresponding to a vehicle collision onto a pole versus a flat barrier
June 15th, 2007
title: Comparison of structural damage and occupant injuries corresponding to a vehicle collision onto a pole versus a flat barrier authors: Hassan, Muhammad Aamir
abstract: afety is of paramount importance to manufacturers of roadway vehicles. Although in the past few years much progress has been made in the field of passenger safety in cars, there is still a strong need for the design of a more crashworthy vehicle in a frontal collision. Therefore, a vehicle crash test performance and how well the vehicle protects the front seat passengers in a head-on-collision is an essential part of the design of the vehicle. Over the past twelve years, the modeling of components and crash analysis of entire vehicles have become increasingly significant. In this thesis, a Ford Taurus model is analyzed in a frontal full-width and offset impact. This thesis describes the comparison of structural damage on a vehicle colliding with rigid pole as compared to the same vehicle model colliding with a barrier. The reason for selecting a rigid pole was to consider the worst-case scenario. The NHTSA has rules and regulations for barrier crashes; however it does not have any standards for pole crashes. In reality, there are many pole related vehicle crashes every year. Pole crashes involve vehicles colliding with utility and traffic light poles. Our purpose was to study the intrusion and injury values for the pole test and compare it with the barrier testing method of NHTSA. These simulations are carried under the New Car Assessment Program (NCAP) and the Insurance Institute for Highway Safety (IIHS). The simulations are obtained using LS-DYNA3D crash code. The rigid barrier, deformable barrier and pole are modeled in MSC/PATRAN. The accelerations at various points are recorded. The occupant compartment intrusions are compared between pole and barrier. Finally the responses of an occupant for the crash tests are studied in Mathematical Dynamical Models (MADYMO) by placing the dummy inside the dyna model. The dummy is placed in the car using extended coupling. A hybrid III 50th percentile male dummy model is used to study the occupant responses. The finite element shoulder and lap belts are modeled in MADYMO. The head accelerations are plotted and the HIC values are calculated. For the crash test the occupant foot injury during compartment intrusion is evaluated by calculating the tibia index and tibia forces. The barrier and the pole test results are compared and the results showed that the intrusions and injury values are more severe in the case of pole impact and in off-set crash there is a severe leg injury.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
abstract: afety is of paramount importance to manufacturers of roadway vehicles. Although in the past few years much progress has been made in the field of passenger safety in cars, there is still a strong need for the design of a more crashworthy vehicle in a frontal collision. Therefore, a vehicle crash test performance and how well the vehicle protects the front seat passengers in a head-on-collision is an essential part of the design of the vehicle. Over the past twelve years, the modeling of components and crash analysis of entire vehicles have become increasingly significant. In this thesis, a Ford Taurus model is analyzed in a frontal full-width and offset impact. This thesis describes the comparison of structural damage on a vehicle colliding with rigid pole as compared to the same vehicle model colliding with a barrier. The reason for selecting a rigid pole was to consider the worst-case scenario. The NHTSA has rules and regulations for barrier crashes; however it does not have any standards for pole crashes. In reality, there are many pole related vehicle crashes every year. Pole crashes involve vehicles colliding with utility and traffic light poles. Our purpose was to study the intrusion and injury values for the pole test and compare it with the barrier testing method of NHTSA. These simulations are carried under the New Car Assessment Program (NCAP) and the Insurance Institute for Highway Safety (IIHS). The simulations are obtained using LS-DYNA3D crash code. The rigid barrier, deformable barrier and pole are modeled in MSC/PATRAN. The accelerations at various points are recorded. The occupant compartment intrusions are compared between pole and barrier. Finally the responses of an occupant for the crash tests are studied in Mathematical Dynamical Models (MADYMO) by placing the dummy inside the dyna model. The dummy is placed in the car using extended coupling. A hybrid III 50th percentile male dummy model is used to study the occupant responses. The finite element shoulder and lap belts are modeled in MADYMO. The head accelerations are plotted and the HIC values are calculated. For the crash test the occupant foot injury during compartment intrusion is evaluated by calculating the tibia index and tibia forces. The barrier and the pole test results are compared and the results showed that the intrusions and injury values are more severe in the case of pole impact and in off-set crash there is a severe leg injury.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
title: Analysis of surface finish in drilling of composites using neural networks authors: Madiwal, Shashidhar
abstract: Composite materials are widely used in the aerospace industry because of their high strength-to-weight ratio. Although they have many advantages, their inhomogeneity and anisotropy pose problems. Because of these properties, machining of composites, unlike conventional metal working, needs more investigation. Conventional drilling of composites is one such field that requires extensive study and research. Among various parameters that determine the quality of a drilled hole, surface finish is of vital importance. The surface finish of a drilled hole depends on speed, feed-rate, material of the work piece, and geometry of the drill bit. This project studied the effect of speed and feed on surface finish and also the optimization of these parameters. Experiments were conducted based on Design of Experiment (DOE) and qualitative verification using Artificial Neural Network (ANN). Relevant behavior of surface finish was also studied. In this project, holes were drilled using a conventional twist drill at different cutting speeds (2,000 to 5,000 rpm) and feed rate was varied from 0.001 to 0.01 ipr for solid carbon fiber laminate (composite material). The other material drilled is BMS 8-276 form 3 (toughened resin system). Also five different drill bits were used to conduct experiments on BMS 8-276 form 3. Speed values were 5,000, 3,000, and 2,000 rpm and feed rates were 0.004, 0.006, and 0.01 ipr. The effect of speed, feed rate, and different drill geometries was analyzed with respect to surface finish in the drilled composites.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
abstract: Composite materials are widely used in the aerospace industry because of their high strength-to-weight ratio. Although they have many advantages, their inhomogeneity and anisotropy pose problems. Because of these properties, machining of composites, unlike conventional metal working, needs more investigation. Conventional drilling of composites is one such field that requires extensive study and research. Among various parameters that determine the quality of a drilled hole, surface finish is of vital importance. The surface finish of a drilled hole depends on speed, feed-rate, material of the work piece, and geometry of the drill bit. This project studied the effect of speed and feed on surface finish and also the optimization of these parameters. Experiments were conducted based on Design of Experiment (DOE) and qualitative verification using Artificial Neural Network (ANN). Relevant behavior of surface finish was also studied. In this project, holes were drilled using a conventional twist drill at different cutting speeds (2,000 to 5,000 rpm) and feed rate was varied from 0.001 to 0.01 ipr for solid carbon fiber laminate (composite material). The other material drilled is BMS 8-276 form 3 (toughened resin system). Also five different drill bits were used to conduct experiments on BMS 8-276 form 3. Speed values were 5,000, 3,000, and 2,000 rpm and feed rates were 0.004, 0.006, and 0.01 ipr. The effect of speed, feed rate, and different drill geometries was analyzed with respect to surface finish in the drilled composites.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
Characterization of CFRP and GFRP composite materials at high strain rate tensile loading
June 15th, 2007
title: Characterization of CFRP and GFRP composite materials at high strain rate tensile loading authors: Deshpande, Anand B.
abstract: High strength-to-weight ratio, directional strength and stiffness are the significant factors, forcing polymer composites into the aerospace, marine and automotive industries. Due to these major factors fuel efficiency and crashworthiness properties are the significant outcomes from use of these advanced materials. This present thesis work deals with experimental study of the in-plane tensile properties of polymer matrix composite materials reinforced by high modulus fibers under Quasi-Static and Hiagh Strain Rate tensile tests. Behavior of Glass fiber-reinforced (GFRP) and Carbon fiber reinforced (CFRP) composite materials is studied. The test coupons are balanced and symmetric in fiber orientation with respect to the test direction. The related experiments are performed with a MTS 810 high rate test machine to determine the mechanical properties of tension test coupons. The specimens were tested separately under quasistatic and high-speed conditions with stroke rates of up to 500 in/s. All specimens were tested to failure in order to characterize the effect of high strain rate on failure strength of the material. In this work, a new method to obtain stress-strain curves for the tensile tests is proposed. The strain rate nature of composite laminates in tensile loadings clearly show that unlike in metals these materials do not exhibit the constant strain rate behavior in case of high strain rate tests. Throughout the test, the strain rate values change due to the dynamics of the system and directional stiffness of the composite laminates. In case of 0° fiber oriented specimens, the fiber properties dominate the matrix properties as fiber strength is much higher than that of matrix materials. For different fiber orientations of the laminates the strain rate varies for the same stroke rate tests as the matrix material starts playing role in case of higher fiber angles. The results show that high strain rates have a significant effect on the properties of the composites coupons. The increment of the ultimate strength with high strain rate is proportional to the strain rate. In the future developments the stress-strain curves obtained from these various tensile tests can be used to insert in a finite element code to develop a material model for computational simulations.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
abstract: High strength-to-weight ratio, directional strength and stiffness are the significant factors, forcing polymer composites into the aerospace, marine and automotive industries. Due to these major factors fuel efficiency and crashworthiness properties are the significant outcomes from use of these advanced materials. This present thesis work deals with experimental study of the in-plane tensile properties of polymer matrix composite materials reinforced by high modulus fibers under Quasi-Static and Hiagh Strain Rate tensile tests. Behavior of Glass fiber-reinforced (GFRP) and Carbon fiber reinforced (CFRP) composite materials is studied. The test coupons are balanced and symmetric in fiber orientation with respect to the test direction. The related experiments are performed with a MTS 810 high rate test machine to determine the mechanical properties of tension test coupons. The specimens were tested separately under quasistatic and high-speed conditions with stroke rates of up to 500 in/s. All specimens were tested to failure in order to characterize the effect of high strain rate on failure strength of the material. In this work, a new method to obtain stress-strain curves for the tensile tests is proposed. The strain rate nature of composite laminates in tensile loadings clearly show that unlike in metals these materials do not exhibit the constant strain rate behavior in case of high strain rate tests. Throughout the test, the strain rate values change due to the dynamics of the system and directional stiffness of the composite laminates. In case of 0° fiber oriented specimens, the fiber properties dominate the matrix properties as fiber strength is much higher than that of matrix materials. For different fiber orientations of the laminates the strain rate varies for the same stroke rate tests as the matrix material starts playing role in case of higher fiber angles. The results show that high strain rates have a significant effect on the properties of the composites coupons. The increment of the ultimate strength with high strain rate is proportional to the strain rate. In the future developments the stress-strain curves obtained from these various tensile tests can be used to insert in a finite element code to develop a material model for computational simulations.
description: Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering