Bending stress in gear teeth for variable surface pressure distribution

AbstractThe bending stress in the root fillets of gear teeth having convex, circular-arc profiles has been calculated using a new analytic model for variable surface pressure distribution. The gear tooth is modeled as a wedge with the load applied at the apex. Graphs of the nondimensional bending stress variation along the tooth length are presented for 14.5 °, 22.5 °, and 30 ° normal pressure angle; 5 °, 25 °, and 45 ° helix angle, and 16, 32, and 80 normal diametral pitch. Tables of the nondimensional maximum root-fillet stress variation are presented for the variation of normal pressure angle, helix angle, and normal diametral pitch. It is shown that gears with larger helix angles or normal diametral pitches or lower normal pressure angles have higher bending stresses for the same value of allowalble surface stress

Uncovering a Connection between the Teachers’ Professional Development Program and Students’ Learning

Most research suggests professional development improves teachers’ knowledge and pedagogy and enhances teachers’ confidence to facilitate a positive attitude about student learning. This study attempted to investigate the connection between teacher professional development program and students’ Learning. This study took Readers’ Theater Teaching Program (RTTP) for professional development as an example to inquiry how participants applied their new knowledge and skills learned from RTTP to their teaching practice and how the impact influenced students’ reading fluency. This study was a two-year project. In the first year, this study focused on designing and implementing RTTP and evaluating participants’ satisfaction of RTTP, what they learned and how they applied it to design their English reading curriculum. In the second year, the study adopted quasi-experimental design approach and evaluated how participants RT instruction influenced their students’ reading fluency. The participants in this study composed two junior high school English teachers and their students. Data was collected from a number of different sources including teaching observation, semi-structured interviews, teaching diary, teachers’ professional development portfolio, pre/post RT content knowledge tests, teacher survey, and students’ reading fluency tests. The results indicated that teachers learned more RT script writing than other specific contents and hold a positive attitude toward RT instruction and considered it as a very wonderful strategy to meet a variety of needs. All of the experimental group students had a big progress in reading fluency after RT instruction.  The evidences from this study indicated that RT English instruction significantly influenced students’ reading fluency and classroom climate. Keywords: Teacher’s Professional Development, Program Evaluation, Readers’ Theater, English Reading Instruction, Reading fluenc