Structural Analysis of Stresses Transferred to a Basketball Backboard from the Rim by Human Loads By: Ryan Ansaldo May 14, 2012 Masters of Engineering Project Proposal Submitted to the Graduate Faculty of Rensselaer Polytechnic Institute to Fulfill the Requirement for the Degree of Masters of Engineering, Mechanical Engineering
Abstract: The purpose of this project is to perform a structural analysis of a basketball rim assembly and investigate the type of stresses imparted on the backboard from the rim. A basketball rim consists of an 18 inch diameter rim and a backboard mount. In the past, professional and collegiate backboards were made of glass and would shatter under human loads. I will perform an analysis on the rim and backboard mount to determine the stresses applied to a backboard and compare them with the yield strengths of common backboard materials.
Introduction/Background: Basketball is a popular sport played all over the world. The sport was invented in 1891 in Springfield, Massachusetts. It was originally invented as an indoor sport played during the winter season. Since its invention, the sport has gone through many evolutions. The original basket was in fact an actual peach basket and was nailed to the wall. In modern times, the basket has been replaced by a rim and net and has a more sophisticated means of being fastened to the backboard. The athletic ability of basketball players has also changed over the years and since the invention of the dunk shot, the basketball rim and backboard have been subjected to many changes and redesigns. Previously the only loads applied to the basketball rim were imparted by the ball which has a weight of approximately 22 ounces. When a dunk is performed, depending on whether or not a player decides to hang, the rim can experience loads in the magnitude of the weight of an above average human weight (since many collegiate and professional basketball players are above average height and weight). The force is then transferred to the bracket which mounts the rim to the backboard. Figure 1: A backboard shattering under the load applied by a player dunking (Reference 1). The stress experienced by the backboard is something that still affects the design of modern day rims as the consequences are not only catastrophic for its function but potentially harmful. Professional basketball rims are made of glass and have shattered when being overstressed. For this reason, the basketball rim and mount are constantly redesigned to improve the function of
the rim. Since basketball has also become a recreational outdoor sport, the materials of backboards have also changed. Problem Description: This project will consist of modeling and analyzing a basketball rim and determining the severity of the stresses imparted on the backboard. The scope of the project will also include investigating how the stresses affect different types of backboards by comparing the stress data to common backboard material yield strengths. If time constraints allow, effects of a more modern and sophisticated backboard design which uses springs as a break away mechanism will also be investigated to verify the effectiveness of modern designs. See Reference (8) See Reference (7) Figure 2: Two patented basketball rim designs Approach: A basketball rim will be modeled in Abaqus/CAE using the dimensions of standard regulation sized rim. The design chosen will be of a rim with no breakaway feature. The mounting bracket will be modeled to be bolted to the backboard using the appropriate constraints. After an suitable mesh is applied to the assembly, a load will be applied to the rim at the point furthest away from the backboard. The load chosen will be of the weight of the retired professional basketball player, Shaquille O Neal who was one of the largest players in the National Basketball Association. The results of interest will be of the stresses experienced at the bracket and backboard. The material of the backboard will then be varied and the results of the stresses will be compared.
Resources Required: The primary resources required are as follows: Abaqus/CAE 6.10-EF1: The finite element analysis software that will be used is Abaqus/CAE. The software allows for modeling of the components involved in the project and running the necessary analyses to obtain the desired results. Microsoft Office: The programs that will be used for word processing and progress reports are within the Microsoft Office software. These programs include but are not limited to Microsoft Word, Excel, and PowerPoint. Mathcad: Mathcad is software specifically for engineering calculations and will be used for organization of any potential hand calculations and as an equation editor. Expected Outcomes: The outcome of this project is to become proficient in the use of Abaqus/CAE and confirm that the stresses experienced on a basketball backboard are severe enough to warrant the many different designs that have been developed to prevent backboard material failure. Milestones: Submit Tentative Project Proposal Draft 5/14/12 Submit Final Project Proposal 5/21/12 o Choose rim design and model in Abaqus/CAE o Find the material properties for assembly o Create an appropriate mesh for assembly o Apply appropriate constrains, loads and BC s Submit First Progress Report 6/11/12 o Perform iterations of analyses with different materials Submit Second Progress Report 7/2/12 o Compile results and interpret data Submit Final Draft 7/16/12 Submit Preliminary Final Report 7/30/12 Submit Final Report 8/6/12
References: (1) http://wannadunk.com/dunks/top-backboard-breaking-dunks/ (2) http://www.docstoc.com/docs/45737429/basketball-rim-assembly---patent- 4433839#viewer-area (3) http://en.wikipedia.org/wiki/dunk_shot (4) http://www.docstoc.com/docs/58850520/multi-directional-break-away-goal--- Patent-7798921#viewer-area (5) http://ezinearticles.com/?basketball-backboard-materials---what-will-your- Basketball-Hoop-Be-Made-of?&id=3311290 (6) http://www.docstoc.com/docs/32634847/backboard-reinforcing-apparatus--- Patent-4588188 (7) http://www.docstoc.com/docs/44250436/direct-mount-for-basketball-backboard- And-Rim---Patent-5207419 (8) http://www.docstoc.com/docs/45737429/basketball-rim-assembly---patent-4433839