Showing papers by "Stephen Ekwaro-Osire published in 2014"

A Novel Method for Calculation Gear Tooth Stiffness for Dynamic Analysis of Spur Gears With Asymmetric Teeth

Abstract: Recently, there have been a number of research activities on spur gears with asymmetric teeth. The benefits of asymmetric gears are: higher load capacity, reduced bending and contact stress, lower weight, lower dynamic loads, reduced wear depths on tooth flank, higher reliability, and higher efficiency. Each of the benefits can be obtained through asymmetric teeth designed correctly. Gears operate in several conditions, such as inappropriate lubrication, excessive loads and installation problems. In working conditions, damage can occur in tooth surfaces due to excessive loads and unsuitable operating conditions. One of the important parameters of the tooth is stiffness, which is found to be reduced proportionally to the severity of the defect by asymmetric tooth design as described in this paper. The estimation of gear stiffness is an important parameter for determining loads between the gear teeth when two sets of teeth are in contact. In this paper, a 2-D tooth model is developed for finite elements analysis. A novel formula is derived from finite element results in order to estimate tooth stiffness depending on the tooth number and pressure angle on the drive side. Tooth stiffness for spur gears with asymmetric teeth is calculated and the results were compared with well known equations in literature.Copyright © 2014 by ASME

Quantification of Uncertainty in Sketches

Abstract: Design Notebooks (DNBs) can be used to assess the information gathering activities, creativity and individual participation within design groups. Moreover DNBs are the communication tools in the overall design process. For communication purposes, DNBs contain information representations (IRs) such as sketches, symbols, text and equations that usually are imprecisely defined. Imprecise or vague IRs may lead to uncertainty in design communication. This work considered the uncertainty in sketches, one of the most widely used IRs in DNBs. The research question of this study is: Can the uncertainty in sketches be quantified? To answer the research question the following specific aims are formulated: identify the type of uncertainty, assess appropriate uncertainty quantification methods and establish a framework to quantify the uncertainty in sketches. The uncertainty in sketches is found to be mainly an epistemic uncertainty and a modified numerical approach was implemented to quantify it. Using the established framework, the uncertainty in sketches has been quantified and further study is recommended to assess its effect on design communication.© 2014 ASME

Elements of Teaching Design under Uncertainty

Abstract: Uncertainty is unavoidable in engineering design. Engineers with knowledge of Design Under Uncertainty (DUU) are able to easily design flexible products with decreased sensitivity to uncertain events. While significant research is being undertaken on DUU, the topic of uncertainty has not been given comparable attention in the area of teaching design. The goal of this paper is to contribute to the enhancement of teaching engineering design. To this effect, the following research question was developed: Is incorporating uncertainty in engineering design important? To solicit the reaction of the stakeholders in this regard, a survey instrument was designed. The survey instrument addresses three aspects of teaching engineering design: the importance of considering uncertainty, the current practice of teaching engineering design, and the way forward. This survey was sent to the design faculty of ABET accredited 89 of the top 100 Graduate Mechanical Engineering schools in the USA. A Power Analysis was performed to estimate statistical significance of the results obtained. Results show that the majority of design faculty in the nation agree that it is important to incorporate the topic of uncertainty in teaching design and that industry will benefit from it. Although many agree on the importance of uncertainty in design education, the majority of educators are still hesitant to integrate uncertainty in teaching design. For this reason, a roadmap of the elements of teaching DUU was constructed and presented. This roadmap is believed to avoid the dilemma and help design faculty to incorporate uncertainty in teaching design. Moreover, while Probability and Statistics courses are usually taught prior to teaching design, there is a need to revitalize students' knowledge of Probability and Statistics in light of teaching uncertainty. P ge 24468.2