Matching Items (11)
Description
The exhaust system is an integral part of any internal combustion engine. A well- designed exhaust system efficiently removes exhaust gasses expelled from the cylinders. If tuned for performance purposes, the exhaust system can also exhibit scavenging and supercharging characteristics. This project reviews the major components of an exhaust system and discusses the proper design techniques necessary to utilize the performance boosting potential of a tuned exhaust system for a four-stroke engine. These design considerations are then applied to Arizona State University's Formula SAE vehicle by comparing the existing system to a properly tuned system. An inexpensive testing method, developed specifically for this project, is used to test the effectiveness of the current design. The results of the test determined that the current design is ineffective at scavenging neighboring pipes of exhaust gasses and should be redesigned for better performance.
ContributorsKnutsen, Jeffrey Scott (Author) / Huang, Huei-Ping (Thesis director) / Steele, Bruce (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2014-05
Description
Nissan technicians consistently test steering friction because it is a critical component for understanding and improving chassis dynamic performance. Due to the inaccuracy of a previous machine used, a new apparatus has been constructed to improve the repeatability and efficiency of a steering friction test. The automation and accurate calibration of the test ensures more accurate data compared to the previous machine. This will lead to more accurate decisions regarding the friction applied between the rack and pinion of a vehicle steering system. The Rack Pull Friction Test is an extremely important test performed by the Nissan Chassis Dynamics Technicians. How the driver experiences the car and if it is suitable for their needs is how the company can sell their vehicles. The test relates to how the customer experiences the steering effort of the vehicles when making small steering wheel corrections. It is important that the customer experiences a minimal steering effort on center feel but still strong enough to maintain control of the vehicle. Since the steering ability is a critical component of car handling, the testing must be performed to the optimum ability. Therefore, the attempt to perfect this test is important to improve the quality and the assurance that the vehicle is at maximum ability.
ContributorsApostol, Andre Aaron (Author) / Liao, Yabin (Thesis director) / LaBorde, Brandon (Committee member) / Bickel, Aaron (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Technologies used in corrective scoliosis surgery do not provide accurate, validated measurements of applied loading on the spine. Proposing a solution to optimize intra-operative load sensing to enhance surgical outcomes, mechanical factors of a capacitive load sensor are examined. Using ASTM D3574-17, experimental methods were performed to verify material homogeneity and validity, to identify critical factors in maximizing compressive strength, and to understand preliminary fatigue behavior for reliability measures. In leveraging the Design of Experiment (DOE) methodology to decrease device variability, the mechanical factors explored were: sensor thickness, diameter ratio of conductive foam, density, and surface hardness. Multiple iterations DOEs identified high thickness and low diameter ratios as significant factors which increase the output response of compressive strength. After identifying the optimal factor combination for the sensor it was found that the maximum experimental load range was 15.57N-16.9lbf. Fatigue testing was then performed on the highest performing factor combination group from the compression results. From the two rounds that were tested on sensor specimen, no significant difference was found between the two groups' rates of changes in thickness per compression. Each round of foam testing resulted in similar thickness values, which suggests that the sensor has potential to perform consistently during a 6-8 hour surgery if a material with improved elasticity and mechanical strength is used. Thus, the experimental procedures fulfill proof-of-concept tests to indicate feasibility of compressive strength and reliability of the sensor's mechanical features. Future experimentations will involve using a different dielectric material in place of the foam, such as a conductive thermoset or thermoplastic elastomer. Additional levels for each factor will be test to test the behavior of the material to yield a higher compressive strength and certainty of reliability. Overall, this study was useful in identifying significant factors for achieving compressive strength, while also providing evidence of the device's potential for reliability during scoliosis surgeries.
ContributorsWieser, Megan Marie (Author) / LaBelle, Jeffrey (Thesis director) / Newcomb, Anna (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
This thesis examines the mechanical properties of an origami inspired structure and its equivalent cube counterpart to determine if this origami configuration is an effective load bearing and energy absorption structure. To test this, a folded paper model was created for visual realization and then 3D printed models were created to undergo compression testing using the Instron 4411. The data from testing was used to create stress-strain curves for each sample, which were then used to determine the maximum stress and toughness of each structure. The performance of these structures was also compared to other known material performance. The origami structure was found to outperform the equivalent cube in both maximum stress it could withstand before failure and toughness. These results are grounds for further research to be done to determine the validity of origami structures as viable alternatives to current material configurations.
ContributorsFong, Jessica (Author) / Jiang, Hanqing (Thesis director) / Kingsbury, Dallas (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Central to current conceptions concerning the function of the nervous system is the consideration of how it manages to maintain precise control for repetitive tasks such as reaching, given the extensive observable mechanical degrees of freedom. Especially in the upper extremities, there are an infinite number of orientations (degrees of freedom) that can produce the same ultimate outcome. Consider, for example, a man in a seated position pointing to an object on a table with his index finger: even if we vastly simplify the mechanics involved in that action by considering three principle joints - the shoulder, elbow, and wrist - there are an infinite number of upper arm orientations that would result in the same position of the man's index finger in three-dimensional space. It has been hypothesized that the central nervous system is capable of simplifying reaching tasks by organizing the DOFs; this suggests that repetitive, simple tasks such as reaching can be planned, that the variability in repetitive tasks is minimized, and that the central nervous system is capable of increasing stability by instantaneously resisting perturbations. Previous literature indicates that variability is decreased and stability increased in trained upper extremity movement. In this study, mechanical discrepancies between violinists of varying levels of experience were identified. It was hypothesized that variability in the positional error (deviation from an expected line of motion) and velocity of the bow, as well as the produced variability in resultant elbow angles, would decrease with increasing proficiency, and that training would have no observable effect on average peak bow velocity. Data acquisition was accomplished by constructing LED triads and implementing a PhaseSpace 3D Motion Capture system. While the positional variance and peak velocity magnitude of the bow appeared unaffected by training (p >> 0.05), more advanced players demonstrated significantly higher variability in bow velocity (p << 0.001). As such, it can be concluded that repetitive training does manifest in changes in variability; however, further investigation is required to reveal the nature of these changes.
ContributorsCulibrk, Robert (Author) / Helms Tillery, Stephen (Thesis director) / Tanner, Justin (Committee member) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The operating principles of bicycle drivetrains have remained largely static since the invention of the derailleur in 1905. A bicycle-specific Continuously Variable Transmission has the potential to eliminate many of these issues. This paper explores the current state of bicycle CVT technology, details the advantages and disadvantages of these designs, and analyzes the many human factors that play into their adoption. Finally, a conceptual design for a novel bicycle CVT is described, and a physical model is created to demonstrate the mechanical principles of operation.
ContributorsBurgard, Kyle (Author) / Singh, Anoop (Thesis director) / Trimble, Steven (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Unmanned aerial vehicles have received increased attention in the last decade due to their versatility, as well as the availability of inexpensive sensors (e.g. GPS, IMU) for their navigation and control. Multirotor vehicles, specifically quadrotors, have formed a fast growing field in robotics, with the range of applications spanning from surveil- lance and reconnaissance to agriculture and large area mapping. Although in most applications single quadrotors are used, there is an increasing interest in architectures controlling multiple quadrotors executing a collaborative task. This thesis introduces a new concept of control involving more than one quadrotors, according to which two quadrotors can be physically coupled in mid-flight. This concept equips the quadro- tors with new capabilities, e.g. increased payload or pursuit and capturing of other quadrotors. A comprehensive simulation of the approach is built to simulate coupled quadrotors. The dynamics and modeling of the coupled system is presented together with a discussion regarding the coupling mechanism, impact modeling and additional considerations that have been investigated. Simulation results are presented for cases of static coupling as well as enemy quadrotor pursuit and capture, together with an analysis of control methodology and gain tuning. Practical implementations are introduced as results show the feasibility of this design.
ContributorsLarsson, Daniel (Author) / Artemiadis, Panagiotis (Thesis advisor) / Marvi, Hamidreza (Committee member) / Berman, Spring (Committee member) / Arizona State University (Publisher)
Created2016
Description
Construction work is ergonomically hazardous, as it requires numerous awkward postures, heavy lifting and other forceful exertions. Prolonged repetition and overexertion have a cumulative effect on workers often resulting in work related musculoskeletal disorders (WMSDs). The United States spends approximately $850 billion a year on WMSDs. Mechanical installation workers experience serious overexertion injuries at rates exceeding the national average for all industries and all construction workers, and second only to laborers. The main contributing factors of WMSDs are ergonomic loads and extreme stresses due to incorrect postures. The motivation for this study is to reduce the WMSDs among mechanical system (HVAC system) installation workers. To achieve this goal, it is critical to reduce the ergonomic loads and extreme postures of these installers. This study has the following specific aims: (1) To measure the ergonomic loads on specific body regions (shoulders, back, neck, and legs) for different HVAC installation activities; and (2) To investigate how different activity parameters (material characteristics, equipment, workers, etc.) affect the severity and duration of ergonomic demands. The study focuses on the following activities: (1) layout, (2) ground assembly of ductwork, and (3) installation of duct and equipment at ceiling height using different methods. The researcher observed and analyzed 15 HVAC installation activities among three Arizona mechanical contractors. Ergonomic analysis of the activities using a postural guide developed from RULA and REBA methods was performed. The simultaneous analysis of the production tasks and the ergonomic loads identified the tasks with the highest postural loads for different body regions and the influence of the different work variables on extreme body postures. Based on this analysis the results support recommendations to mitigate long duration activities and exposure to extreme postures. These recommendations can potentially reduce risk, improve productivity and lower injury costs in the long term.
ContributorsHussain, Sanaa Fatima (Author) / Mitropoulos, Panagiotis (Thesis advisor) / Wiezel, Avi (Committee member) / Guarascio-Howard, Linda (Committee member) / Arizona State University (Publisher)
Created2011
Description
There has been a vast increase in applications of Unmanned Aerial Vehicles (UAVs) in civilian domains. To operate in the civilian airspace, a UAV must be able to sense and avoid both static and moving obstacles for flight safety. While indoor and low-altitude environments are mainly occupied by static obstacles, risks in space of higher altitude primarily come from moving obstacles such as other aircraft or flying vehicles in the airspace. Therefore, the ability to avoid moving obstacles becomes a necessity
for Unmanned Aerial Vehicles.
Towards enabling a UAV to autonomously sense and avoid moving obstacles, this thesis makes the following contributions. Initially, an image-based reactive motion planner is developed for a quadrotor to avoid a fast approaching obstacle. Furthermore, A Dubin’s curve based geometry method is developed as a global path planner for a fixed-wing UAV to avoid collisions with aircraft. The image-based method is unable to produce an optimal path and the geometry method uses a simplified UAV model. To compensate
these two disadvantages, a series of algorithms built upon the Closed-Loop Rapid Exploratory Random Tree are developed as global path planners to generate collision avoidance paths in real time. The algorithms are validated in Software-In-the-Loop (SITL) and Hardware-In-the-Loop (HIL) simulations using a fixed-wing UAV model and in real flight experiments using quadrotors. It is observed that the algorithm enables a UAV to avoid moving obstacles approaching to it with different directions and speeds.
for Unmanned Aerial Vehicles.
Towards enabling a UAV to autonomously sense and avoid moving obstacles, this thesis makes the following contributions. Initially, an image-based reactive motion planner is developed for a quadrotor to avoid a fast approaching obstacle. Furthermore, A Dubin’s curve based geometry method is developed as a global path planner for a fixed-wing UAV to avoid collisions with aircraft. The image-based method is unable to produce an optimal path and the geometry method uses a simplified UAV model. To compensate
these two disadvantages, a series of algorithms built upon the Closed-Loop Rapid Exploratory Random Tree are developed as global path planners to generate collision avoidance paths in real time. The algorithms are validated in Software-In-the-Loop (SITL) and Hardware-In-the-Loop (HIL) simulations using a fixed-wing UAV model and in real flight experiments using quadrotors. It is observed that the algorithm enables a UAV to avoid moving obstacles approaching to it with different directions and speeds.
ContributorsLin, Yucong (Author) / Saripalli, Srikanth (Thesis advisor) / Scowen, Paul (Committee member) / Fainekos, Georgios (Committee member) / Thangavelautham, Jekanthan (Committee member) / Youngbull, Cody (Committee member) / Arizona State University (Publisher)
Created2015
Description
This thesis investigates the feasibility, development, and accuracy of implementing two inline sets of uniaxial strain gauges for a neurosurgical force sensing suction and retraction (FSSR) instrument to determine force metrics such as magnitude, location, and orientation of applied force in real time. Excess force applied during a neurosurgery could lead to complications for the patient during and after surgery, thus there is clinical need for a quantitative real time tool-tissue feedback for various surgical tools. A force-based metric has been observed to be highly correlated to improving not only surgical training but also the outcome of surgical procedures. Past literature and previous studies attempted to design a force sensing retractor. Although previous investigations and prototypes have developed methods and protocols to detect small magnitude forces applied, they lacked the ability to detect the magnitude of force without knowing the distance of the applied force. This is a critical limitation because the location of a net applied force can vary along a retractor during surgery and is often unseen and cannot be measured during surgery. The main goal of this current investigation is to modify the previous design of the force sensing suction retractor (FSSR) device with a new placement of strain gauges, utilizing a novel configuration of an aligned pair of strain gauge arrangement with only knowing the distance between the pair of gauge sets and the strain data collected. The FSSR was a stainless steel suction tube retrofitted with 8 gauges: two sets of 4 gauges aligned and separated radially by 90 degrees within each set. Calibrations test and blind load tests were conducted to determine accuracy of the instrument for detecting the force metrics. It was found that a majority of 40 variations for the calibration tests maintained a percent difference under 10% when comparing actual and calculated values. Specifically, using calibration test 2 for blind test 2 the orientation yielded a calculated value that was 2.1 degrees different. Blind test 2 for the magnitude yielded a calculated value that was .135 N different, which is a 9.104 % difference. Also, blind test 2 set 1 and set 2 for the location of applied load from set 1 and set 2 yielded a calculated value that was 7.334 mm different, which is an 8.95 % difference for set 1 and a 15.63 % difference for set 2. Possible limitations and errors in the protocol that may have increased the discrepancy between actual and calculated values include how accurate the strain gauges were placed in terms of both alignment and radial orientation. Future work in regards to improving the new FSSR prototype, is to first develop a better method to ensure accurate placement of gauges, both in paired alignment between sets and radial separation within sets. Overall, the clinical considerations for a force sensing tool is aimed at minimizing patient injury during surgery, devices such as the force sensing suction retractor is an example of novel technology that could become a standard technology within the operating room.
ContributorsXu, Jake Johnny (Author) / Buneo, Christopher (Thesis director) / Kelly, Brian (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05