Multidisciplinary Engineered Dynamic Systems

The Multidisciplinary Engineered Dynamic Systems research group focuses on collaborative research at the interface of engineering disciplines including dynamics, vibration, acoustics, signal processing, molecular biology, and controls. These disciplines are becoming increasingly important due to advances in nanotechnology, higher machinery speeds, demanding operational loads, compact and lightweight designs, and new engineered materials.

Experimental work that employs high-speed processors, signal processing and embedded control processor, smart sensors, and actuators is evolving rapidly. When faced with complaints about noise or unpleasant vibration, many global manufacturers turn to the Multidisciplinary Engineered Dynamic Systems research group to investigate and improve their systems' behavior.

Researchers employ experimental and simulation-based methods to turn a grating whine into a gentle hum that exists below the realm of human perception. With modern lab facilities that include anechoic and reverberation chambers, researchers are well equipped to undertake studies of components and systems in full-scale operation.

Faculty + Research = Discovery

Our department boasts world-class faculty who have access to numerous innovative research labs and are committed to discovery and learning. This encompasses a range of research areas, experiences, and expertise related to multidisciplinary engineered dynamic systems. Learn more about our faculty and their research interests:

Research Projects

Our faculty engage in a number of research projects, many of which are publicly funded. A sample listing of recent research projects related to multidisciplinary engineered dynamic systems appears below. You can also view a broader list of research projects taking place across the mechanical engineering department.

Recently Funded Projects

Carbon Nanotube Speaker for Exhaust Active Noise Control

Investigators
Principal Investigator: Andrew Barnard
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics

Confidential

Awarded Amount: $154,037

Development of Dynamic Torsional Measurement Capability using Hybrid Electric Motor - Year 2

Investigators
Principal Investigator: Darrell Robinette
Co-Investigator: Jason Blough
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics
Project Abstract
As the role of the torque converter in the vehicle has changed with the increasing need for better fuel efficiency it has become important to better understand the torsional isolation properties of the torque converter. The torsional isolation performance is accomplished by the fluid coupling portion of the torque converter at low speeds, and by the torque converter clutch assembly once the converter clutch is applied. Recent changes in the operational profile of the torque converter to improve fuel efficiency require that the clutch be applied at lower and lower vehicle speeds. In addition, the use of reduced displacement engines and engine cylinder deactivation results in greater engine torsional excitations at lower engine firing frequencies, demanding increased isolation capability from the torque converter. Due to these changes in operation, as well as the increased torque carrying capacity of the clutch assembly, there is an important need to be able to study the response of the torque converter and clutch assembly to torsional inputs which are representative of the torsional excitation provided by an engine.
 
This project seeks to develop the necessary test stand to perform these required torsional isolation studies. The hardware will be developed from a hybrid electric drive motor. This project aims to use this motor to develop a torsional dynamometer that can be used to input a torsional excitation to a torque converter that has frequency content similar to an operating internal combustion engine.
 
Once the dynamometer is functional it will be used to study the isolation performance of torque converter clutch and isolator assemblies. Year two of this project will seek to validate the setup and begin testing torque converter clutch and isolator assemblies for damping characteristics. The experimental data will be used to validate a model methodology for torque converter clutch dampers on select production designs.
Awarded Amount: $92,457

Tailorable Resonant Plate Testing

Investigators
Principal Investigator: Jason Blough
Co-Investigator: Charles Van Karsen
Co-Investigator: James DeClerck
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics
Overview:
The goal of this program is to gain insight into tunable resonant plate testing procedures. The project will use a combination of modeling and testing to attempt to develop insight which reduces test time and expands the range of possible testing. The following is a breakdown of the tasks:
 
Statement of Work:
Research will explore how to model the resonant plate and fixture dynamics. Analytical and experimental studies will be performed to understand the critical parameters in more accurately controlling and understanding the design of the resonant plate and fixture to extend its range of testing.
  • FEA models of the resonant plate and fixture will be created.
  • FEA models will be used to understand how each parameter of the test system effects the shock response spectrum.
  • Identify potential limits for the shock response spectrums which can be reproduced within the framework of the resonant plate test system.
  • Propose design approaches and tailoring strategies which will enable the resonant plate test system to deliver a specified shock response spectrum (within the capability limits of the resonant plate test system framework).
  • Mechanisms to add damping to the resonant plate will be explored both analytically and experimentally as a potential tailoring strategy.
 
Deliverable(s): All FEA models and test data will be provided. A report will be written which summarizes the analytical and experimental modeling and testing as well as any damping mechanisms/devices which were evaluated and their effectiveness.
Awarded Amount: $204,000
Keywords: FEA Modeling Resonant Plate

Ongoing Projects

On Integrating New Capability into Coastal Energy Conversion Systems

Investigators
Principal Investigator: Ossama Abdelkhalik
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics
Overview:
MTU will analyze and simulate the power capture from arrays of wave energy converters (WECs) with and without the presence of an object. Nonlinear WECs will be analyzed and exploited for more energy capture. For object detection, MTU will develop an estimator. In addition to having a model that detects the presence of an object, the estimator will use that model and account for uncertainties that we have in the model and also measurement errors; in any case we need to know statistical characteristics about these uncertainties and errors. MTU will participate in the WEC array overall design, analysis, modeling and simulations; control design for Design 2, nonlinear modeling and control, and topology optimization.
Awarded Amount: $405,139
Keywords: Wave Energy Converters Sustainable Energy Optimization

REU: CPS: Breakthrough: Toward Revolutionary Algorithms for Cyber-Physical Systems Architecture Optimization

Investigators
Principal Investigator: Ossama Abdelkhalik
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics

Overview:

Design optimization of cyber-physical systems (CPS) includes optimizing the system architecture (topology) in addition to the system variables. Optimizing the system architecture renders the dimension of the design space variable (the number of design variables to be optimized is a variable.) This class of Variable-Size Design Space (VSDS) optimization problems arises in many CPS applications including (1) microgrid design, (2) automated construction, (2) optimal grouping, and (3) space mission design optimization.

Evolutionary Algorithms (EAs) present a paradigm for statistical inference that implements a simplified computational model of the mechanisms embedded in natural evolution, with potential to solve this problem. However, existing EAs cannot optimize among solutions of different architectures because of the inherent strategy for coding the variables in EAs. Existing EAs resembles natural evolution in which a given architecture can evolve by improving the state of its variables but cannot be revolutionized. Inspired by the concept of hidden genes in biology, this project investigates revolutionary optimization algorithms that can optimize among different solution architectures and autonomously develop new architectures that might not be known a priori, yet are more fit solution architectures. Efficacy of the new algorithms for CPS is evaluated in the context of space mission design optimization.

Intellectual Merit:

There is an increasing demand in the scientific community for autonomous design optimization tools that can revolutionize systems designs and capabilities. Most existing optimization algorithms can only search for optimal solutions in a fixed-size design space; and hence they cannot be used for solution architecture optimization. Few existing algorithms can search for optimal solutions in VSDS problems; however these are problem-specific algorithms and cannot be used as a general framework for VSDS optimization. This project investigates the novel concept of hidden genes in coding the variables in evolutionary algorithms so that the resulting algorithms can be used for optimizing VSDS problems. The key innovation in these new algorithms is the new coding strategies. In addition, in this project, the standard operations in EAs will be replaced by new operations that are defined to enable revolutionizing a current population of solution architectures using the new coding strategy. The Pl's recent research results, in the context of space mission design optimization, demonstrate that the hidden genes optimization algorithms can search for optimal solutions among different solution architectures, revolutionize an initial population of solutions, and construct new solution architectures that are more fit than the initial population solutions.

Awarded Amount: $269,735

CAREER: Steerable Powered Ankle-foot Prostheses for Increased Mobility in Amputees

Investigators
Principal Investigator: Mohammad Rastgaar Aagaah
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics

Overview:

Mobility is a key factor to well-being, both emotionally (through increased independence and decreased depression and anxiety) and physically {through reduced disease risk, bone maintenance, muscle strength, and weight control). Over a million US citizens are limb amputees, primarily lower leg amputees. This program will 1) work to improve the mobility of lower extremity amputees through research in design and control of powered ankle-foot prostheses, which mimic the steering mechanism of human gait by having two controllable degrees of freedom (DOF) and 2) integrate research with education and outreach to inspire and equip a diverse next generation of engineers. To work toward these long-term goals, this program will develop – and use in education and outreach - a lightweight, cable-driven, powered ankle-foot prosthesis capable of steering and traversing slopes by learning from human ankle impedance in the sagittal and frontal planes during gait.

This research is based on the hypothesis that an ankle-foot prosthesis capable of applying torques and impedance modulation in both the sagittal and frontal planes, similar to the human ankle, will improve maneuverability and increase mobility by lowering the metabolic cost of gait - both when walking straight and turning. Advances in powered prostheses have shown the ability to reduce metabolic cost and increase the preferred speed of gait for unilateral transtibial amputees during straight walking by providing sufficient power during push-off. Powered prostheses can also reduce asymmetrical gait patterns and thus may lower risk of secondary complications. However, studies show that turning steps account for 8-50% of steps, depending on activity, and thus may account for 25% of daily steps. Modulation of ankle impedance in the sagittal and frontal planes plays a major role in controlling lateral and propulsive ground reaction forces. While a non-amputee relies on hip movement in the coronal plane and the moment generated in the ankle joint, an amputee using a passive prosthesis uses the hip extension in the sagittal plane as a gait strategy. The hypothesis is supported by preliminary results which show a large inversion of the ankle during the stance period of step turns, indicating a significant deviation of ankle rotations from the straight-step pattern.

Understanding the role of the ankle in locomotion and developing a platform for design and control of new ankle-foot prostheses will allow exploratory research and education. Research includes: Thrust 1: Estimate ankle impedance in the sagittal and frontal planes during the stance period of gait; Thrust 2: Develop a powered ankle-foot prosthesis with two controllable DOF; Thrust 3: Evaluate the design and control of the prosthesis using an evaluation platform and with below-knee amputees through collaboration with Mayo Clinic; and Thrust 4: Education/Outreach: Utilize the steerable ankle-foot prosthesis for education, outreach, and research experiences to impact diverse K-12, community college, undergraduate, and graduate students.

The work is significant in that it will contribute 1) new knowledge about multivariable impedance modulation of the human ankle during the stance period of gait, an area not yet fully explored, and 2) a unique framework for developing and evaluating powered ankle-foot prostheses. The steerable ankle-foot prosthesis is innovative because it will enable amputees to walk with a more natural gait by using the ankle joint, rather than merely the hip and knee. Development of this novel platform will be a substantial step toward the long-term goal of improving design and maneuverability in lower extremity assistive prostheses and robots.

Robotics is a high-impact way to attract the attention of future engineers. Outreach activities are included to that spark and sustain STEM interest in pre-college students, especially  underrepresented minorities. Development of an inexpensive powered ankle-foot prosthesis will improve well-being of Wounded Warriors and civilian amputees, while at the same time inspiring and training the future STEM workforce. In addition, a newly developed a low-cost EMG-controlled manipulator will be included as an educational platform that will be used in outreach programs to teach fundamentals of mechatronics, robotics, and biomechanics to K-12, community college, undergraduate, and graduate students.

Awarded Amount: $640,412

Past Projects

Development of Dynamic Torsional Measurement Capability using Hybrid Electric Motor – Year 1

Investigators
Principal Investigator: Jason Blough
Co-Investigator: Wayne Weaver
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics
Project Abstract and Research Summary
As the role of the torque converter in the vehicle has changed with the increasing need for better fuel efficiency it has become important to better understand the torsional isolation properties of the torque converter. The torsional isolation performance is accomplished by the fluid coupling portion of the torque converter at low speeds, and by the torque converter clutch assembly once the converter clutch is applied. Recent changes in the operational profile of the torque converter to improve fuel efficiency require that the clutch be applied at lower and lower vehicle speeds. In addition, the use of reduced displacement engines and engine cylinder deactivation results in greater engine torsional excitations at lower engine firing frequencies, demanding increased isolation capability from the torque converter. Due to these changes in operation, as well as the increased torque carrying capacity of the clutch assembly, there is an important need to be able to study the response of the torque converter and clutch assembly to torsional inputs which are representative of the torsional excitation provided by an engine.
 
This project seeks to develop the necessary test stand to perform these required torsional isolation studies. The hardware will be developed from a hybrid electric drive motor. This project aims to use this motor to develop a torsional dynamometer that can be used to input a torsional excitation to a torque converter that has frequency content similar to an operating internal combustion engine.Once the dynamometer is functional it will be used to study the isolation performance of torque converter clutch and isolator assemblies, with specific emphasis on the turbochargers impact. The specifics of turbomachinery are examined, including the thermodynamics associated with energy extraction and gas compression.
Awarded Amount: $94845

Sound Power Measurement System for Fire Protection Systems

Investigators
Principal Investigator: Andrew Barnard
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics
Michigan Tech will provide support for acoustic baseline testing of the Inergen product line of fire suppression systems. MTU will travel to Tyco's facility in Marinette, WI, to measure the sound absorption coefficient in the two acoustic test chambers. These coefficients will then be used to the measure sound power levels of gas discharge nozzles. A Lab VIEW data acquisition program will be designed to collect temporally varying sound power levels in the test chambers, record time histories of sound pressure, and display results. This program will be used to collect acoustic data on a baseline set of nozzle configurations to be mutually analyzed by Tyco and MTU personnel. MTU will also create a basic design tutorial on predicting sound pressure level in any room, based on the measured sound power levels in Tyco's test chambers.
At the end of the effort, MTU participants will travel to Marinette, WI, to present findings, discuss follow-on design studies, and data set demonstrating concept validation.
Awarded Amount: $28,352
Keywords: Acoustic

Suspended Floor Material Testing

Investigators
Principal Investigator: Andrew Barnard
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics

Michigan Tech will test materials according to EN 29052-1. There will be two batches of testing. The first will consist of 10 baseline materials. The second batch will consist of 7 prototype materials. Each material will include averaging of data from three test samples. Dynamic stiffness from the EN 29052-1 test will be reported to the sponsor. In addition, damping values, using the half-power bandwidth method, will be reported for A-B comparisons. It should be noted that these damping values will not represent as-installed damping values for the materials. Finally, Michigan Tech will provide a load-deflection curve for each material based on results from an MTS machine test. Four of the baseline materials will also undergo a creep test, where they will be loaded over a 48 hour period and re-tested for dynamic stiffness. Data will be presented in the form of a 1-2 page report for each material, showing raw data and computed values of dynamic stiffness, damping ratio, and load-deflection.

Awarded Amount: $22,188

Assist in Planning of Development of RMCP Platform Concepts

Investigators
Principal Investigator: Jason Blough
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics
Awarded Amount: $16,500

Support of RMCP Phase II SBIR

Investigators
Principal Investigator: Jason Blough
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics
Awarded Amount: $72,500

Low-Cost Underwater Glider Fleet for Littoral Marine Research

Investigators
Principal Investigator: Nina Mahmoudian
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics

This research is focused on development of innovative practical solutions for control of individual and multiple unmanned underwater vehicles (UUVs) and address challenges such as underwater communication and localization that currently limit UUV use. More specifically, the Nonlinear and Autonomous Systems Laboratory (NAS Lab) team are developing a rigorous framework for analyzing and controlling underwater gliders (UGs) in harsh dynamic environments for the purpose of advancing efficient, collaborative behavior of UUVs.

Underwater gliders are now utilized for much more than long-term, basin-scale oceanographic sampling. In addition to environmental monitoring, UGs are increasingly depended on for littoral surveillance and other military applications. This research will facilitate the transition between academic modeling/simulation problem solving approach to real-world Navy applications. The importance of this research is evident in the Littoral BattleSpace Sensing (LBS) Program contract at the Naval Space and Naval Warfare Systems Command for 150 underwater gliders, designated the LBS-G. These gliders will be operated by the Navy in forward areas to rapidly assess and exploit environmental characteristics to improve the maneuvering of ships and submarines and advance the performance of fleet sensors.

Research results will provide the coordination tools necessary to enable the integration of these efficient and quiet vehicles as part of a heterogeneous network of autonomous vehicles capable of performing complex, tactical missions. The objective is to develop practical, energy-efficient motion control strategies for both individual and multiple UGs while performing in inhospitable, uncertain, and dynamic underwater environments.

The specific goals of this project are twofold. The first goal is to design and fabricate a fleet of low-cost highly maneuverable lightweight underwater gliders. The second goal is to evaluate the capability of the single and multiple developed UGs in littoral zones. The proposed work will develop UGs that would share the buoyancy-driven concept with the first generation of gliders called “legacy gliders.” However, the NAS Lab UGs will be smaller in size, lighter in weight, and lower in price than legacy gliders. This will result in more affordable and novel UG applications. Moreover, the NAS Lab design to development approach allows for technological innovation that overcomes known challenges and responds to unexpected needs that arise during testing. Therefore, the significance of this research is that it will enable implementation of recently developed efficient motion planning algorithms, multi-vehicle coordination algorithms, and extension of these algorithms in realistic conditions where absolute location and orientation of each vehicle is not known and the time-varying flow field is not locally determined.

Awarded Amount: $139,231

SGAS Drive Train Model Calibration

Investigators
Principal Investigator: Gordon Parker
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics

Introduction

Calibration is an important step in creating a physical model that can be used for predictive control system design. IMECO has a MATLAB/Simulink model of their Steering Gear Actuation System (SGAS). It contains parameters that can be classified as known (e.g. control system gains), known with uncertainty (e.g. mass properties) and unknown (e.g. damping coefficients). IMECO has also obtained experimental data that can be used to run the model and compare model outputs to sensor measurements. An optimization-based method for identifying the model parameters is needed to help automate the calibration process.

Statement of Work

Using the model and experimental data supplied by IMECO, calibrate the model using advanced numerical optimization strategies. Separate calibration parameters for several data sets will be developed in addition to a single calibration across multiple data sets. While the calibration is of primary importance, development of a methodology for automating the process will also be developed.

Awarded Amount: $47,598

Control System Design for Cargo Transfer from Offshore Supply Vessels to Large Deck Vessels

Investigators
Principal Investigator: Gordon Parker
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics

Introduction

There is a wide range of hydraulic extending-boom and knuckle-boom cranes in use on marine vessels. These cranes are often used in dynamic motion environments for cargo transfer and small boat handling. The ability to safely launch and recover small boats in elevated sea states for naval, Coast Guard and oceanographic purposes is currently a focus of investigation within these communities.

The purpose of this investigation is to extend the research begun under SBIR topic N06-

057, "Cargo Transfer from Offshore Supply Vessels to Large Deck Vessels" to improve the performance of hydraulic marine cranes in the dynamic offshore environment. In addition, the lessons learned during the development of the Integrated Rider Block Tagline System (IRBTS), the Platform Motion Compensation System (PMC) and the Pendulation Control System (PCS) for the rigid-boom, level-luffing marine cranes used for container handling on sealift ships will be incorporated into a final integrated, modular kit to improve cargo transfer with these extending-boom and knuckle-boom cranes.

Phase II Technical Objectives

The goal of Phase II is to develop and demonstrate a modular solution for crane pendulation and motion control suitable for a wide range of existing U.S. Navy ship cranes. Phase I clearly showed that pendulation control can be modularized by implementing ship motion cancellation using the crane's existing drive system and active load damping using a retrofit damping device. In that work, a specific crane design was considered and the study was strictly proof-of-concept through simulation.

Phase II focuses on identifying the range of cranes for which the modular approach is feasible, developing the analysis and design work flow needed to design and deploy the modular solution, and demonstrating both the process and the performance on a particular crane. The incremental technical objectives of Phase II are listed below.

    1. The analysis and design process for implementing modular pendulation and motion control on any crane,

    2. The development of a modular crane control system (MCCS) "kit" including refinement of the key subsystems (sensors, actuation, algorithms),

    3. A phased demonstration of MCCS using 1/12th and larger scale testbeds.

At the conclusion of Phase II, the objective is to have a fully functioning MCCS system demonstrating ship motion cancellation, active payload damping on an articulated crane similar to those currently deployed on numerous U.S. Navy and civilian ships. The Phase II Option will focus this development on a design that can be implemented on the hydraulic extending-boom crane, currently proposed for use on the JHSV.

Awarded Amount: $268,953

Understanding the Cavity Mode of Tires

Investigators
Principal Investigator: Jason Blough
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics

Background:

The purpose of this research is to be able to predict the natural frequencies associated with the cavity modes of tires mounted oil wheels. Ford has experienced difficulties in the past when these natural frequencies have aligned themselves with the natural frequencies of other vehicle components and hence caused an objectionable noise in the vehicle. The goal of this project is to provide the tools to Ford to allow them to make decisions in advance of mounting tire/wheel combinations on vehicles by estimating what these tire cavity natural frequencies will be. It is anticipated that to fully understand the frequencies of the tire cavity modes will require a combination of modeling and experimental testing.

Approach:

To meet these objectives start with a finite element model of the cavity of a tire mounted on a wheel. The initial model includes effectively a rigid tire and wheel. This model is not a coupled vibro-acoustic model but instead just an estimate the natural frequencies of the tire cavity itself with zero velocity boundary conditions. This model will be modified to simulate the change in the tire cavity shape when the wheel is loaded in a static configuration. The results of the loaded and unloaded models are compared to help to understand the effects of changing the tire cavity's shape. If the results of this model show promise, simpler modeling methods will be explored.

The next step in the modeling process includes a flexible tire and wheel and be a fully coupled vibro-acoustic model. In this model, the wheel will have actual material properties assigned while the tire will be modeled as an isotropic material with estimated material properties that will be iterated to achieve natural frequencies of the coupled system similar to those measured in the laboratory of a stationary tire. This model will then be modified to a statically loaded condition and the model re-run to observe the effects of loading the tire on the natural frequencies.

Models will be validated experimentally by testing a tire/wheel assembly in the laboratory at MTU. Testing will be done in the both the unloaded and the statically loaded case by exciting both the wheel and the tire patch in separate tests. Natural frequencies will be estimated from all tests and used to validate the models. Models and testing will be performed on several different tire/wheel combinations to assess the ability to estimate the natural frequencies of different configurations. Based on the results of the modeling and testing the final deliverable from this project will be the simplest approach that can be determined for estimating the natural frequencies of a tire cavity based on a minimum set of information or data.

Awarded Amount: $64,000

Analysis of Mobile Haulage Equipment Operating Dynamics

Investigators
Principal Investigator: Nina Mahmoudian
College/School: College of Engineering
Department(s): Mechanical Engineering-Engineering Mechanics

Overview:

Injuries and fatalities occur every year when mine workers are struck and pinned by mobile haulage equipment in underground and surface mines. To prevent these accidents, the mining industry is beginning to adopt proximity detection systems to this class of equipment. These systems use various technologies, such as RFID, RADAR, infrared and others. The problem with this adaptation is that manufacturers are designing systems without sufficient scientific investigation to determine all of the parameters. NIOSH intends to conduct a thorough investigation of these accidents and develop innovative technology that will increase workers safety around mobile haulage equipment.

One of the first steps in this endeavor will be to determine the vehicle dynamics for the majority of mobile haulage equipment. Characteristics such as acceleration, tractive effort, braking, steering, and other parameters are examined in conjunction with human motion data to create 3D computer simulations.

Because of time and resource constraints, NIOSH is exploring the possibility of acquiring the vehicle operating dynamics parameters through an outside contract. The contractor would be required to become familiar with multiple types of mine haulage equipment. The calculated dynamics should be applicable to all machines of each type. NIOSH could provide some limited information on this equipment, but the majority would have to be acquired by the contractor. The majority of contract work consists of calculating and determining vehicle dynamics for the various types of mine haulage.

Task 1: Create a database detailing available the types of mine haulage equipment available.  This database details the equipment manufacturers, their model types, and usage. Collect necessary physical and operational data about each identified type of mine haulage equipment in order to categorize them and provide a minimum set of vehicles to dynamically model.

Task 2: In order to model a particular machine type, a representative construct needs to be given dimensions and weight distributions similar in nature to all machines in that machine type category. Using the database compiled, specifically the physical data collected and develop a representative construct for each category identified in the previous task from the collected mine haulage equipment physical characteristics.

Task 3: Determine the vehicle kinematics and dynamics for the majority of mobile haulage equipment that fit into each category. Characteristics such as acceleration, tractive effort, braking, steering, and other parameters are determined and mathematical modeling of associated equations of motion generated for each construct. It is expected that the equations of motion in the derived construct mathematical models can be used to simulate these various machine types in a simulation software package such as Jack.

Awarded Amount: $24,000

Characterization of Torque Converter Cavitation Level during Speed Ratio Operation - Year 3

Investigators
Principal Investigator: Jason Blough
Co-Investigator: Carl Anderson
Co-Investigator: Mark Johnson, PE
College/School: College of Engineering,  School of Technology
Department(s): Mechanical Engineering-Engineering Mechanics

Introduction/ Abstract

Torque converter torus designs have evolved from axially long and round shapes to axially thin and elliptical shapes as automatic transmission content has increased in numbers of gears and in damping capability of the torque converter clutch. Future designs will include torque converters with even thinner tori with the torque converter to be used strictly as a vehicle launch device and the converter clutch applied in low gear at low vehicle speed.  These changes result in improved vehicle fuel economy, however, thinner torus torque converters are at increased risk for high levels of cavitation. The fluid in a small torus torque converter versus large at the same level of torque has greater pressure gradients across the blades of the converter pump, turbine, and stator. Greater pressure gradients result in lower pressures on the low pressure side of converter element blades which can lead to cavitation. Smaller torus converters also contain less transmission fluid which can lead to localized regions of higher temperature, further contributing to increased risks for high levels of cavitation. Understanding torque converter cavitation and noise characteristics, and the Influences of design parameters and operating conditions on cavitation level is vital to enabling new generations of transmission designs.

This research seeks to build upon knowledge gained from previous torque converter cavitation and noise studies executed at MTU. Previous research has established that moderate levels of cavitation are present in many torque converters under normal operating conditions. This research intends to quantify the level of cavitation present under normal and overload operating conditions and to develop a method to compare designs relative to design parameters and loading.

 Introduction

Starting in 1997, extensive research was conducted into techniques for detecting the presence of cavitation in the flow field of an operating torque converter. These studies have produced novel methodologies for sensing the onset of cavitation and quantifying its intensity at various operating conditions using microwave telemetry and specially instrumented torque converters. In 2000, a separate project was undertaken to develop a technique to acquire and evaluate noise generated by a torque converter during operation using acoustic measurements. Large quantities of data were acquired in both vehicles and in the dynamometer lab, advanced software was used to disassemble the noise spectrum into its critical components. Very successful measurement and analysis methodologies were developed, but no attempt was made to utilize these tools on converters of widely different sizes and designs. In 2004, a project was undertaken in which converters of different sizes and designs were operated over a range of charge pressures and torques at the stall operating condition. Noise data was acquired during the tests, processed by the recently developed numerical techniques, and non-dimensionalized or otherwise correlated against the converter's design and load parameters. The acoustical method of cavitation sensing was employed to similarly define the influence of converter design on cavitation potential. This data was used to validate the dimensional analysis approach to cavitation prediction suggested by the earlier work. To provide the precision and repeatability necessary for testing performed, both the dynamometers and hydraulic system of the test facility were updated to full computer control. The body of work has nicely correlated the cavitation characteristics of torque converters at stall conditions. In 2007, a project was initiated to characterize torque converter cavitation through a range of speed ratio operation and normal input torque and power levels. Test data was analyzed to develop dimensionless models to predict the speed ratio for cavitation desinense based on torque converter design parameters and operating conditions.

The research established that moderate levels of cavitation are present with no adverse effects in many production torque converters functioning under normal operating conditions. There are no complaints of objectionable noise from cavitation and no evidence of material wear or damage due to the implosion of cavitation bubbles. As torque converter torus designs continue to get smaller, this may no longer be the case. This study proposes to develop a method to measure and quantify the level of cavitation in a torque converter, determine criteria for acceptable levels of cavitation, test a matrix of torque converter designs for cavitation, and perform dimensional analysis to create a model capable of predicting cavitation level based on design parameters and operating conditions

Awarded Amount: $98,837