Showing papers by "Stephen Ekwaro-Osire published in 2007"

An Alternative Mechanism of Non-contact Anterior Cruciate Ligament Injury During Jump-landing: In-vitro Simulation

Abstract: In the United States, an estimated 100,000 anterior cruciate ligament (ACL) injuries occur every year. Despite decades of research, to this date, the mechanism or mechanisms of non-contact ACL injuries are not well understood. This is primarily because trials cannot be conducted on live subjects to understand the injury mechanism, and it is difficult to instrument a live human knee to measure the response of tissues during dynamic activities. In this paper, we present a dynamic knee injury simulator capable of in-vitro modeling of the ACL injury during jump-landing activity. This system was used to simulate jump-landing on cadaveric knees and to successfully test which conditions would result in isolated ACL injury. A restricted flexion of the hip (a hip that flexes minimally or not at all during landing), combined with low quadriceps and hamstring force levels during landing were found to be conducive to ACL injury. Elevated levels of quadriceps force prevented the injury from occurring even under restricted hip flexion conditions. The measured strain rates in the ACL tissue during injury causing activities were over 250%/s.

Design notebooks as indicators of student participation in team activities

Abstract: The motivation of this study is to enhance the traditional uses of design notebooks as teamwork assessment tools. Here, this is done by relating the individual student's entries in the design notebook to peer evaluations. The objective of this study is to show that design notebooks are also effective indicators of good teamwork participation. During the course, students are introduced to essential elements of reflective thinking in the engineering design, the design process, and teamwork. A pedagogical approach developed by the authors is used to guide the students to the completion of their engineering design project. This is a pedagogical approach to creative engineering design education that has previously been shown to establish a close relationship with and within design teams of students. The students are also instructed on the writing of effective design notebooks. The design notebooks are evaluated on five essential elements based on rubrics developed. A separate tool for peer evaluation of the team members is developed and applied. The correlation of the data obtained from design notebooks to that from the peer evaluation is discussed. Suggestions are made on how design notebooks could be enhanced to provide information on team dynamics.

Impact Of Student Selection Of Design Projects On Team Performance

Abstract: In the capstone design courses, the instructor can choose among different strategies of assigning students to project teams. One of these strategies allows the students select the project they would like to work on from a list. This sometimes proceeds in an ad-hoc manner. Currently, literature offers limited research that looks at the reasons why students select certain projects. Furthermore, the work examining the impact of this selection on team performance is also limited. The objective of this study is to examine the impact of the students’ project selection on team performance. This is carried out by (1) investigating the rationalization students undertake during the selection process, and (2) analyzing data concerning the influence of the selection on team performance. Two instruments are presented in this paper that can be used to analyze the impact of student selection of design projects on the team performance. These instruments are also used to track the types of projects the students select, such as faculty projects, industry supported projects, student initiated projects, and projects for design competitions. A systematic methodology, based on the students’ rankings of all the projects for assigning students to their preferred choice of projects, is also presented. Whereas the data presented shows that students generally read carefully the project description, the majority of students prefer the project clients to make short presentations. To analyze the impact of project choice on team performance, four categories, based on the student project choice, were proposed. Teams whose majority did not get their first choice of project, showed the largest drop between the mid-semester peer ratings compared to end-of-semester peer ratings. This study was performed at two universities.

Designing Against Head Injury While Considering Neck Injury

Abstract: Without a doubt, the major concern of vehicle design is safety ¨C increasing the survival chance of driver and passenger during a crash and decreasing the risk of injury. Safety features, such as seat belt, seat cushion with crash tubing, or frontal and side impact airbags, have been proposed to protect the occupants from the secondary impacts. This study adapts a transdisciplinary approach, combining research from epidemiology and injury biomechanics as a basis for identifying design problem areas and variable trade-offs. The objectives of this paper are to review literature on head injury and neck injury, and to provide suggestions for designing against head injury while considering neck injury. Since the head injury is mainly caused by contact, the fundamental design principle is to minimize any hard surface protrusion. Especially sharp objects, such as dash shade and mirrors, must be removed or kept outside the striking range in any configuration. There are several principles that can be used, in any combination, to achieve the required crush depth: (1) to prevent skull damage and brain trauma, locally modifying the design by removing rigid high points and moving hard assemblies down or under; (2) to decelerate head and torso at the same rate (which will also decrease the risk of neck injury) by modifying hard structures to make them crush or collapsible and obtaining as much clearance. There is a need to design and construct test equipment that can be used to test neck injury and head injury simultaneously.

Optimization of Load Uniformity for Triangular Tube Using Non-Linear Programming

Abstract: The paper focuses on two topics, optimizing the proposed triangular tube for crashworthiness and solving a non‐linear programming problem by a “mapping” technique, which the condition of Lagrange Multiplier Theorem is violated within the feasible region. The purpose of studying optimized triangular tubes is to prepare them for redesigning vehicle bumpers. The dimension optimization of triangular tube is carried out for its thickness and lateral length, based on the accomplished shape optimization under an impact. The load uniformity is taken as the objective function, which is defined as the ratio of maximum peak force and means crushing force. Meanwhile the mean crushing force and absorbed energy are treated as constraints. Based on FEA analysis, the regression functions for load uniformity, mean crushing force, and absorbed energy are formulated by RSM. The result has shown that triangular tube possesses an optimization region, under which the better‐integrated property can be achieved to supply a more safety environment for vehicular occupants.