Aldo Ferri | Georgia Institute of Technology (original) (raw)

Papers by Aldo Ferri

Research paper thumbnail of The Impact of the Physics, Statics, and Mechanics Sequence on Student Retention and Performance in Mechanical Engineering

2018 ASEE Annual Conference & Exposition Proceedings

started as an Academic Professional in the Woodruff School of Mechanical Engineering in the summe... more started as an Academic Professional in the Woodruff School of Mechanical Engineering in the summer of 2014. She received a BS in Mechanical Engineering and a BS in Astronomy from the University of Illinois in 2005. After graduation she went to work for Northrop Grumman Space Technology in Redondo Beach, California. In her time at Northrop Grumman Kathryn served as a material scientist specializing in the failure analysis of microelectronics on several defense satellite programs. In 2009 she left industry to pursue a PhD in Mechanical Engineering at the University of Colorado, where her research focused on the development of novel biomaterials for cardiovascular tissue engineering. At the GWW School of Mechanical Engineering, Kathryn teaches the junior level Machine Design and senior level Capstone Design courses, as well as advises the BSMS students.

Research paper thumbnail of Board 53: Program to Integrate Mobile, Hands-on Experiments into the ME, AE, and ECE Curriculum

2019 ASEE Annual Conference & Exposition Proceedings

His research spans nearly 20 years, including evaluating the effectiveness of learning technologi... more His research spans nearly 20 years, including evaluating the effectiveness of learning technologies at both the K-12 and higher ed. levels. Rob brings to C21U research foci in online pedagogy and effective practices, alternative learning spaces, learning analytics, and tools/strategies to help close the digital divide for economically disadvantaged students. He has presented both nationally and internationally on cutting-edge learning technologies and managing grants, programs, and research in their use. Rob held faculty positions at Penn State University and Johns Hopkins University prior to running his own educational technology research consulting firm for seven years. He continues to teach online courses in the sociology of education, criminology, and juvenile delinquency for the University of Colorado Denver. Rob earned his Ph.D. in sociology from Emory University in 1998.

Research paper thumbnail of BYOE: Mobile Experiment for Signals and Systems - Analysis of a Guitar String

2013 ASEE Annual Conference & Exposition Proceedings

She spent two years working for Honeywell, Inc. as a controls engineer. She has spent 10 years wo... more She spent two years working for Honeywell, Inc. as a controls engineer. She has spent 10 years working on hands-on education and has won several awards including the Harriet B. Rigas Award from the IEEE Education Society.

Research paper thumbnail of Development of Team-Based Hands-On Learning Experiences

2020 ASEE Virtual Annual Conference Content Access Proceedings

Prof. Craig has been on the faculty at Georgia Tech for more than fifty years and continues to te... more Prof. Craig has been on the faculty at Georgia Tech for more than fifty years and continues to teach as an emeritus professor and to develop classroom engagement methods and tools. His past research is in the general area of experimental structural mechanics, dynamics and structural control with applications to aerospace and earthquake engineering. He is coauthor of a textbook on structural analysis with application to aerospace structures.

Research paper thumbnail of Optimization of Vibration Isolation Mounts With Internal Rotation in Response to Shock Type Inputs

Volume 8: 28th Conference on Mechanical Vibration and Noise, 2016

The design of isolation mounts is of critical importance in the protection of structures and sens... more The design of isolation mounts is of critical importance in the protection of structures and sensitive equipment from damage or failure. Simultaneous protection from both shock and vibration is particularly challenging because of the broadband nature of the input signal and because of the deleterious effect of damping on high-frequency isolation. Prior work by the authors has shown that chains of translating and rotating mass/spring elements can act as a “mechanical filter” for input disturbances. If designed correctly, the isolator is able to trap some of the input energy into rotational vibration, preventing it from damaging the structure. However, in finite-length chains, wave reflections can result in secondary pulses that hit the structure and can diminish the effectiveness of the isolator. In this paper, the design of dynamic isolation mounts is improved using an optimization technique. Numerical simulations are performed using a parametric model of the new mount design. The s...

Research paper thumbnail of A controls approach to improve classroom learning using cognitive learning theory and course analytics

2016 American Control Conference (ACC), 2016

The availability of educational technology and new modes of instruction present unprecedented opp... more The availability of educational technology and new modes of instruction present unprecedented opportunities for improving the educational effectiveness of engineering courses. This paper discusses a controls approach for developing and improving courses over the span of several semesters using a wide array of metrics to monitor student learning. Changes in course content, pacing, and format were introduced to improve consistency across sections and across semesters in terms of metrics such as student performance and student workload. Results are shown for a course that has an annual enrollment of 1100 students and is taught in a blended/flipped format with online components provided by two MOOCs.

Research paper thumbnail of Low-Overhead Reinforcement Learning-Based Power Management Using 2QoSM

Journal of Low Power Electronics and Applications

With the computational systems of even embedded devices becoming ever more powerful, there is a n... more With the computational systems of even embedded devices becoming ever more powerful, there is a need for more effective and pro-active methods of dynamic power management. The work presented in this paper demonstrates the effectiveness of a reinforcement-learning based dynamic power manager placed in a software framework. This combination of Q-learning for determining policy and the software abstractions provide many of the benefits of co-design, namely, good performance, responsiveness and application guidance, with the flexibility of easily changing policies or platforms. The Q-learning based Quality of Service Manager (2QoSM) is implemented on an autonomous robot built on a complex, powerful embedded single-board computer (SBC) and a high-resolution path-planning algorithm. We find that the 2QoSM reduces power consumption up to 42% compared to the Linux on-demand governor and 10.2% over a state-of-the-art situation aware governor. Moreover, the performance as measured by path err...

Research paper thumbnail of Acoustic Response to Large Structural Perturbations

Structural-acoustic design and analysis can benetit greatly by a knowledge of how changes or pert... more Structural-acoustic design and analysis can benetit greatly by a knowledge of how changes or perturbations in the nominal structural affect acoustic response. Due to high sensitivity, f~st-order perturbati[)t] analysis is sometime restricted to ve~ small perturbations h addition, higher+rder analysis may fail to converge due to system resonances. This paper examines the calculation of higher order sensitivity dam in a finite element framework, The local sensitivity data is applied to the construction of a binomial series approximation and a equivalent Pad&approximation of the perturbed nominal model. The Pad&approximation is found to be vasfly superior. BACKGROUND

Research paper thumbnail of Development of a Portable Experimental Platform to Demonstrate the Role of Material and Cross-section in Beam Bending

2019 ASEE Annual Conference & Exposition Proceedings

Prof. Craig has been on the faculty at Georgia Tech for more than fifty years and continues to te... more Prof. Craig has been on the faculty at Georgia Tech for more than fifty years and continues to teach as an emeritus professor and to develop classroom engagement methods and tools. His past research is in the general area of experimental structural mechanics, dynamics and structural control with applications to aerospace and earthquake engineering. He is coauthor of a textbook on structural analysis with application to aerospace structures.

Research paper thumbnail of Use of a Vertically Integrated Project Team to Develop Hands-On Learning Modules

2017 ASEE Annual Conference & Exposition Proceedings

been a faculty member in the School of Mechanical Engineering at Georgia Tech, where he now serve... more been a faculty member in the School of Mechanical Engineering at Georgia Tech, where he now serves as the Associate Chair for Undergraduate Studies. His research areas are in the fields of dynamics, controls, vibrations, and acoustics. He is also active in course and curriculum development. He is a Fellow of the ASME.

Research paper thumbnail of Dynamic Modeling of Flat Belt Drives Using the Elastic-Perfectly-Plastic Friction Law

Volume 4: 7th International Conference on Multibody Systems, Nonlinear Dynamics, and Control, Parts A, B and C, 2009

An analysis of a physically-motivated friction model called the Elastic/Perfectly-Plastic (EPP) f... more An analysis of a physically-motivated friction model called the Elastic/Perfectly-Plastic (EPP) friction model was performed on a steadily rotating flat belt drive. The EPP friction law is modeled as an elastic spring in series with an ideal Coulomb damper. The belt kinematics were developed and the nonlinear equations of motion and equilibrium solutions were derived using Hamilton’s Principle. Unlike the belt mechanics analyzed with Coulomb friction, the current study predicts the absence of adhesion zones. A stability analysis demonstrates that the non-linear equilibrium solution found is stable under local perturbation. A two-pulley belt drive with equal radii is analyzed and the dynamic response is studied. The results are compared to those computed using a dynamic finite element model. Excellent agreement between the two methods is documented.

Research paper thumbnail of Peeling of Long, Straight Carbon Nanotubes from Surfaces

Journal of Nanotechnology, 2014

Research paper thumbnail of Empirical Correlation of the Morphology of Coiled Carbon Nanotubes with Their Response to Axial Compression

Journal of Nanotechnology, 2014

The mechanical response of thirteen different helical multi-walled carbon nanocoils to axial comp... more The mechanical response of thirteen different helical multi-walled carbon nanocoils to axial compression is reported. Each nanocoil was attached to the apex of a cantilever probe tip; its dimensions and orientation relative to the tip apex were determined with scanning electron microscopy. The atomic force microscope was employed to apply a cyclic axial load on the nanocoil. Its mechanical response was determined by simultaneous collection of the thermal resonance frequency, displacement, and oscillation amplitude of the cantilever-nanotube system in real time. Depending upon compression parameters, each coil underwent buckling, bending, and slip-stick motion. Characteristic features in the thermal resonance spectrum and in the force and oscillation amplitude curves for each of these responses to induced stress are presented. Following compression studies, the structure and morphology of each nanocoil were determined by transmission electron microscopy. The compression stiffness of ...

Research paper thumbnail of Sensitivity analysis of coupled structural-acoustic problems using perturbation techniques

The Journal of the Acoustical Society of America, 1997

The analysis of acoustic radiation and scattering from submerged elastic structures is an importa... more The analysis of acoustic radiation and scattering from submerged elastic structures is an important and challenging problem. Often, numerical solutions are hampered by the fact that the acoustic pressure field can be very sensitive to structural detail. In this paper, a procedure for obtaining the sensitivity of a structural-acoustic system to structural perturbations is presented. The theoretical development assumes a finite element description of the structure and a boundary element description of the fluid. The analysis includes full coupling between the fluid and the structure, and can accommodate both internal and/or external fluid regions. The types of perturbations are limited to those that do not alter the geometry of the wetted surface, but are otherwise completely general in nature. The technique is then applied to acoustic scattering from a cylindrical shell. Two perturbations are considered: A change in the shell thickness and a change in the elastic modulus. The effect of these structural per...

Research paper thumbnail of Scattering of a plane wave from a cylinder partially coated by a layer modeled as a dissipative fluid

The Journal of the Acoustical Society of America, 1990

Research paper thumbnail of Dynamic Modeling and Stability Analysis of Flat Belt Drives Using an Elastic/Perfectly Plastic Friction Law

Journal of Dynamic Systems, Measurement, and Control, 2011

This paper presents an analysis of a nonlinear (piecewise linear) dynamical model governing stead... more This paper presents an analysis of a nonlinear (piecewise linear) dynamical model governing steady operation of a flat belt drive using a physically motivated elastic/perfectly plastic (EPP) friction law. The EPP law models frictional contact as an elastic spring in series with an ideal Coulomb damper. As such, the friction magnitude depends on the stretch of the elastic belt and is integral to the solution approach. Application of the extended Hamilton’s principle, accounting for nonconservative work due to friction and mass transport at the boundaries, yields a set of piecewise linear equations of motion and accompanying boundary conditions. Equilibrium solutions to the gyroscopic boundary value problem are determined in closed form together with an expression for the minimum value of the EPP spring constant needed to transmit a given torque. Unlike equilibrium solutions obtained from a strict Coulomb law, these solutions omit adhesion zones. This finding may be important for inte...

Research paper thumbnail of On the Equivalence of the Incremental Harmonic Balance Method and the Harmonic Balance-Newton Raphson Method

Journal of Applied Mechanics, 1986

Research paper thumbnail of Error Estimates for Harmonic-Balance Solutions of Nonlinear Dynamical Systems

50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2009

Research paper thumbnail of Multiple scattering from submerged bodies dissimilar acoustical properties

A numerical solution for a two-body acoustical multiple scattering problem based on the analytica... more A numerical solution for a two-body acoustical multiple scattering problem based on the analytical infinite series solution of the wave equation was developed. FORTRAN 77 codes implementing this solution were written which were capable of simulating the case of two spheres of arbitrary radius and distinct material properties subject to an acoustic plane wave of arbitrary incidence. Far-field solutions involving permutations of the two "degenerate" boundary conditions (pressure release and rigid) were compared to solutions obtained with the combined Helmholtz integral equation formulation problem (CHIEF) program. Surface pressure and velocities were calculated. The case in which one of the spheres is fully elastic and the other pressure release is modeled and the results verified experimentally

Research paper thumbnail of Optimizing Efficiency and Effectiveness in a Mechanical Engineering Laboratory using Focused Modules

2017 ASEE Annual Conference & Exposition Proceedings

Dr. MacNair serves as Director of Laboratory Development in the Woodruff School, and manages Juni... more Dr. MacNair serves as Director of Laboratory Development in the Woodruff School, and manages Junior and Senior level laboratories in Mechanical Engineering. He develops innovative laboratory experiences based on lessons-learned from the maker movement and real-world industrial challenges, and is building an "ecosystem" of academic laboratory equipment and curriculum resources which allows universities to collaborate on the development and execution of effective undergraduate laboratory experiences. Dr. MacNair joined the Woodruff School in 2015 after working for the Georgia Tech Research Institute, and as an Educational Consultant for Enable Training and Consulting and National Instruments before that. He received his BS in Mechanical Engineering in 2008 and his PhD in Robotics in 2013, both from Georgia Tech. In his non-work hours, David serves as co-founder and board member of the Southeast Maker Alliance (Southeast US Regional Leadership for the Maker Movement) as well as Director of Maker Faire Atlanta. He also guides the development and investment of various Atlanta-based foundations and non-profits targeting K-12 education.

Research paper thumbnail of The Impact of the Physics, Statics, and Mechanics Sequence on Student Retention and Performance in Mechanical Engineering

2018 ASEE Annual Conference & Exposition Proceedings

started as an Academic Professional in the Woodruff School of Mechanical Engineering in the summe... more started as an Academic Professional in the Woodruff School of Mechanical Engineering in the summer of 2014. She received a BS in Mechanical Engineering and a BS in Astronomy from the University of Illinois in 2005. After graduation she went to work for Northrop Grumman Space Technology in Redondo Beach, California. In her time at Northrop Grumman Kathryn served as a material scientist specializing in the failure analysis of microelectronics on several defense satellite programs. In 2009 she left industry to pursue a PhD in Mechanical Engineering at the University of Colorado, where her research focused on the development of novel biomaterials for cardiovascular tissue engineering. At the GWW School of Mechanical Engineering, Kathryn teaches the junior level Machine Design and senior level Capstone Design courses, as well as advises the BSMS students.

Research paper thumbnail of Board 53: Program to Integrate Mobile, Hands-on Experiments into the ME, AE, and ECE Curriculum

2019 ASEE Annual Conference & Exposition Proceedings

His research spans nearly 20 years, including evaluating the effectiveness of learning technologi... more His research spans nearly 20 years, including evaluating the effectiveness of learning technologies at both the K-12 and higher ed. levels. Rob brings to C21U research foci in online pedagogy and effective practices, alternative learning spaces, learning analytics, and tools/strategies to help close the digital divide for economically disadvantaged students. He has presented both nationally and internationally on cutting-edge learning technologies and managing grants, programs, and research in their use. Rob held faculty positions at Penn State University and Johns Hopkins University prior to running his own educational technology research consulting firm for seven years. He continues to teach online courses in the sociology of education, criminology, and juvenile delinquency for the University of Colorado Denver. Rob earned his Ph.D. in sociology from Emory University in 1998.

Research paper thumbnail of BYOE: Mobile Experiment for Signals and Systems - Analysis of a Guitar String

2013 ASEE Annual Conference & Exposition Proceedings

She spent two years working for Honeywell, Inc. as a controls engineer. She has spent 10 years wo... more She spent two years working for Honeywell, Inc. as a controls engineer. She has spent 10 years working on hands-on education and has won several awards including the Harriet B. Rigas Award from the IEEE Education Society.

Research paper thumbnail of Development of Team-Based Hands-On Learning Experiences

2020 ASEE Virtual Annual Conference Content Access Proceedings

Prof. Craig has been on the faculty at Georgia Tech for more than fifty years and continues to te... more Prof. Craig has been on the faculty at Georgia Tech for more than fifty years and continues to teach as an emeritus professor and to develop classroom engagement methods and tools. His past research is in the general area of experimental structural mechanics, dynamics and structural control with applications to aerospace and earthquake engineering. He is coauthor of a textbook on structural analysis with application to aerospace structures.

Research paper thumbnail of Optimization of Vibration Isolation Mounts With Internal Rotation in Response to Shock Type Inputs

Volume 8: 28th Conference on Mechanical Vibration and Noise, 2016

The design of isolation mounts is of critical importance in the protection of structures and sens... more The design of isolation mounts is of critical importance in the protection of structures and sensitive equipment from damage or failure. Simultaneous protection from both shock and vibration is particularly challenging because of the broadband nature of the input signal and because of the deleterious effect of damping on high-frequency isolation. Prior work by the authors has shown that chains of translating and rotating mass/spring elements can act as a “mechanical filter” for input disturbances. If designed correctly, the isolator is able to trap some of the input energy into rotational vibration, preventing it from damaging the structure. However, in finite-length chains, wave reflections can result in secondary pulses that hit the structure and can diminish the effectiveness of the isolator. In this paper, the design of dynamic isolation mounts is improved using an optimization technique. Numerical simulations are performed using a parametric model of the new mount design. The s...

Research paper thumbnail of A controls approach to improve classroom learning using cognitive learning theory and course analytics

2016 American Control Conference (ACC), 2016

The availability of educational technology and new modes of instruction present unprecedented opp... more The availability of educational technology and new modes of instruction present unprecedented opportunities for improving the educational effectiveness of engineering courses. This paper discusses a controls approach for developing and improving courses over the span of several semesters using a wide array of metrics to monitor student learning. Changes in course content, pacing, and format were introduced to improve consistency across sections and across semesters in terms of metrics such as student performance and student workload. Results are shown for a course that has an annual enrollment of 1100 students and is taught in a blended/flipped format with online components provided by two MOOCs.

Research paper thumbnail of Low-Overhead Reinforcement Learning-Based Power Management Using 2QoSM

Journal of Low Power Electronics and Applications

With the computational systems of even embedded devices becoming ever more powerful, there is a n... more With the computational systems of even embedded devices becoming ever more powerful, there is a need for more effective and pro-active methods of dynamic power management. The work presented in this paper demonstrates the effectiveness of a reinforcement-learning based dynamic power manager placed in a software framework. This combination of Q-learning for determining policy and the software abstractions provide many of the benefits of co-design, namely, good performance, responsiveness and application guidance, with the flexibility of easily changing policies or platforms. The Q-learning based Quality of Service Manager (2QoSM) is implemented on an autonomous robot built on a complex, powerful embedded single-board computer (SBC) and a high-resolution path-planning algorithm. We find that the 2QoSM reduces power consumption up to 42% compared to the Linux on-demand governor and 10.2% over a state-of-the-art situation aware governor. Moreover, the performance as measured by path err...

Research paper thumbnail of Acoustic Response to Large Structural Perturbations

Structural-acoustic design and analysis can benetit greatly by a knowledge of how changes or pert... more Structural-acoustic design and analysis can benetit greatly by a knowledge of how changes or perturbations in the nominal structural affect acoustic response. Due to high sensitivity, f~st-order perturbati[)t] analysis is sometime restricted to ve~ small perturbations h addition, higher+rder analysis may fail to converge due to system resonances. This paper examines the calculation of higher order sensitivity dam in a finite element framework, The local sensitivity data is applied to the construction of a binomial series approximation and a equivalent Pad&approximation of the perturbed nominal model. The Pad&approximation is found to be vasfly superior. BACKGROUND

Research paper thumbnail of Development of a Portable Experimental Platform to Demonstrate the Role of Material and Cross-section in Beam Bending

2019 ASEE Annual Conference & Exposition Proceedings

Prof. Craig has been on the faculty at Georgia Tech for more than fifty years and continues to te... more Prof. Craig has been on the faculty at Georgia Tech for more than fifty years and continues to teach as an emeritus professor and to develop classroom engagement methods and tools. His past research is in the general area of experimental structural mechanics, dynamics and structural control with applications to aerospace and earthquake engineering. He is coauthor of a textbook on structural analysis with application to aerospace structures.

Research paper thumbnail of Use of a Vertically Integrated Project Team to Develop Hands-On Learning Modules

2017 ASEE Annual Conference & Exposition Proceedings

been a faculty member in the School of Mechanical Engineering at Georgia Tech, where he now serve... more been a faculty member in the School of Mechanical Engineering at Georgia Tech, where he now serves as the Associate Chair for Undergraduate Studies. His research areas are in the fields of dynamics, controls, vibrations, and acoustics. He is also active in course and curriculum development. He is a Fellow of the ASME.

Research paper thumbnail of Dynamic Modeling of Flat Belt Drives Using the Elastic-Perfectly-Plastic Friction Law

Volume 4: 7th International Conference on Multibody Systems, Nonlinear Dynamics, and Control, Parts A, B and C, 2009

An analysis of a physically-motivated friction model called the Elastic/Perfectly-Plastic (EPP) f... more An analysis of a physically-motivated friction model called the Elastic/Perfectly-Plastic (EPP) friction model was performed on a steadily rotating flat belt drive. The EPP friction law is modeled as an elastic spring in series with an ideal Coulomb damper. The belt kinematics were developed and the nonlinear equations of motion and equilibrium solutions were derived using Hamilton’s Principle. Unlike the belt mechanics analyzed with Coulomb friction, the current study predicts the absence of adhesion zones. A stability analysis demonstrates that the non-linear equilibrium solution found is stable under local perturbation. A two-pulley belt drive with equal radii is analyzed and the dynamic response is studied. The results are compared to those computed using a dynamic finite element model. Excellent agreement between the two methods is documented.

Research paper thumbnail of Peeling of Long, Straight Carbon Nanotubes from Surfaces

Journal of Nanotechnology, 2014

Research paper thumbnail of Empirical Correlation of the Morphology of Coiled Carbon Nanotubes with Their Response to Axial Compression

Journal of Nanotechnology, 2014

The mechanical response of thirteen different helical multi-walled carbon nanocoils to axial comp... more The mechanical response of thirteen different helical multi-walled carbon nanocoils to axial compression is reported. Each nanocoil was attached to the apex of a cantilever probe tip; its dimensions and orientation relative to the tip apex were determined with scanning electron microscopy. The atomic force microscope was employed to apply a cyclic axial load on the nanocoil. Its mechanical response was determined by simultaneous collection of the thermal resonance frequency, displacement, and oscillation amplitude of the cantilever-nanotube system in real time. Depending upon compression parameters, each coil underwent buckling, bending, and slip-stick motion. Characteristic features in the thermal resonance spectrum and in the force and oscillation amplitude curves for each of these responses to induced stress are presented. Following compression studies, the structure and morphology of each nanocoil were determined by transmission electron microscopy. The compression stiffness of ...

Research paper thumbnail of Sensitivity analysis of coupled structural-acoustic problems using perturbation techniques

The Journal of the Acoustical Society of America, 1997

The analysis of acoustic radiation and scattering from submerged elastic structures is an importa... more The analysis of acoustic radiation and scattering from submerged elastic structures is an important and challenging problem. Often, numerical solutions are hampered by the fact that the acoustic pressure field can be very sensitive to structural detail. In this paper, a procedure for obtaining the sensitivity of a structural-acoustic system to structural perturbations is presented. The theoretical development assumes a finite element description of the structure and a boundary element description of the fluid. The analysis includes full coupling between the fluid and the structure, and can accommodate both internal and/or external fluid regions. The types of perturbations are limited to those that do not alter the geometry of the wetted surface, but are otherwise completely general in nature. The technique is then applied to acoustic scattering from a cylindrical shell. Two perturbations are considered: A change in the shell thickness and a change in the elastic modulus. The effect of these structural per...

Research paper thumbnail of Scattering of a plane wave from a cylinder partially coated by a layer modeled as a dissipative fluid

The Journal of the Acoustical Society of America, 1990

Research paper thumbnail of Dynamic Modeling and Stability Analysis of Flat Belt Drives Using an Elastic/Perfectly Plastic Friction Law

Journal of Dynamic Systems, Measurement, and Control, 2011

This paper presents an analysis of a nonlinear (piecewise linear) dynamical model governing stead... more This paper presents an analysis of a nonlinear (piecewise linear) dynamical model governing steady operation of a flat belt drive using a physically motivated elastic/perfectly plastic (EPP) friction law. The EPP law models frictional contact as an elastic spring in series with an ideal Coulomb damper. As such, the friction magnitude depends on the stretch of the elastic belt and is integral to the solution approach. Application of the extended Hamilton’s principle, accounting for nonconservative work due to friction and mass transport at the boundaries, yields a set of piecewise linear equations of motion and accompanying boundary conditions. Equilibrium solutions to the gyroscopic boundary value problem are determined in closed form together with an expression for the minimum value of the EPP spring constant needed to transmit a given torque. Unlike equilibrium solutions obtained from a strict Coulomb law, these solutions omit adhesion zones. This finding may be important for inte...

Research paper thumbnail of On the Equivalence of the Incremental Harmonic Balance Method and the Harmonic Balance-Newton Raphson Method

Journal of Applied Mechanics, 1986

Research paper thumbnail of Error Estimates for Harmonic-Balance Solutions of Nonlinear Dynamical Systems

50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2009

Research paper thumbnail of Multiple scattering from submerged bodies dissimilar acoustical properties

A numerical solution for a two-body acoustical multiple scattering problem based on the analytica... more A numerical solution for a two-body acoustical multiple scattering problem based on the analytical infinite series solution of the wave equation was developed. FORTRAN 77 codes implementing this solution were written which were capable of simulating the case of two spheres of arbitrary radius and distinct material properties subject to an acoustic plane wave of arbitrary incidence. Far-field solutions involving permutations of the two "degenerate" boundary conditions (pressure release and rigid) were compared to solutions obtained with the combined Helmholtz integral equation formulation problem (CHIEF) program. Surface pressure and velocities were calculated. The case in which one of the spheres is fully elastic and the other pressure release is modeled and the results verified experimentally

Research paper thumbnail of Optimizing Efficiency and Effectiveness in a Mechanical Engineering Laboratory using Focused Modules

2017 ASEE Annual Conference & Exposition Proceedings

Dr. MacNair serves as Director of Laboratory Development in the Woodruff School, and manages Juni... more Dr. MacNair serves as Director of Laboratory Development in the Woodruff School, and manages Junior and Senior level laboratories in Mechanical Engineering. He develops innovative laboratory experiences based on lessons-learned from the maker movement and real-world industrial challenges, and is building an "ecosystem" of academic laboratory equipment and curriculum resources which allows universities to collaborate on the development and execution of effective undergraduate laboratory experiences. Dr. MacNair joined the Woodruff School in 2015 after working for the Georgia Tech Research Institute, and as an Educational Consultant for Enable Training and Consulting and National Instruments before that. He received his BS in Mechanical Engineering in 2008 and his PhD in Robotics in 2013, both from Georgia Tech. In his non-work hours, David serves as co-founder and board member of the Southeast Maker Alliance (Southeast US Regional Leadership for the Maker Movement) as well as Director of Maker Faire Atlanta. He also guides the development and investment of various Atlanta-based foundations and non-profits targeting K-12 education.