WORCESTER POLYTECHNIC INSTITUTE

Transcription

1 WORCESTER POLYTECHNIC INSTITUTE MECHANICAL ENGINEERING DEPARTMENT DESIGN OF MACHINE ELEMENTS ME-3320, B 2018 Lecture 04 October 2018

2 Office hours: Announcements (also in the website of our course) Prof. Furlong, M to Th, 10:00-10:50 AM or by appointment (HL-152) TA: By appointment MathCad Help sessions (attendance will be recorded): Mondays 4:00-4:50 pm in HL-230 Design Project: list of members (due Today) Exams: please review website for details

3 Topics for today Introduction to MathCAD: step functions Shear, moment, torsion diagrams: examples w/singularity functions Progress report specifications Questions to ask (design project): e.g., geometry of the designs, location of bearings?, distance between bearings?, types of fixtures, materials, height of the tower, load types and boundary conditions, etc.

4 Internal forces and moments Shear, Normal, and Bending moments Internal forces (determination of shear and moment diagrams) Component FBD Sections Internal: moments, shear, and normal forces at point C

5 Internal forces and moments Shear, Normal, and Bending moments Section at point C z y x

6 Shear and bending-moment diagrams A suspended bar supports a 600-lb engine. Plot the shear and moment diagrams for the bar. Method of sections: plot using step functions + MathCad 1.5 ft 1.5 ft

7 Shear and bending-moment diagrams Method of sections: plot using step functions + MathCad ME-3320: more details in Thursday s help session

8 Shear and bending-moment diagrams Singularity functions

9 Shear and bending-moment diagrams Singularity functions

10 Shear and bending-moment diagrams Singularity functions Loading function: Shear function: Moment function: q(x) V ( x) M ( x) q( x) dx V ( x) dx

11 Shear and bending-moment diagrams Singularity functions: in-class examples (loading functions)

12 Shear and bending-moment diagrams Singularity functions: in-class examples (loading functions)

13 Shear and bending-moment diagrams Singularity functions: example E1 Determine and plot the shear and moment functions for the simply supported beam shown:

14 Shear and bending-moment diagrams Singularity functions: example E1 - MathCad

15 Shear and bending-moment diagrams Singularity functions: example E2 Determine and plot the shear and moment functions for the cantilever beam shown:

16 Shear and bending-moment diagrams Singularity functions: example E2 - MathCad

17 Shear and bending-moment diagrams Singularity functions: example E3 Determine and plot the shear and moment functions for the beam shown:

18 Shear and bending-moment diagrams Singularity functions: example E3 - MathCad

19 Design project: movie clip Discussions and design tasks Source:

20 Design project for this course: objectives Do note: this is an unstructured, engineering, project! (e.g., design teams must fully define design parameters, constraints, etc.) Detailed design of the main shaft and selection of corresponding bearings and fixtures of a Vestas V kw wind turbine Detailed design of the tower of a Vestas V kw wind turbine

21 Design project: Schedule (refer to our entire course outline in course webpage) o Monday, November 05. Progress Report #1 Background research. Design constrains. FBD s. Assumptions o Monday, November 19. Progress Report #2 Full static and dynamic analysis o Monday, December 03. Progress Report #3 Full stress analysis. Preliminary designs o Friday, December 14. Final Report Final proposed designs and detail report

22 Design project: Report Specifications ME-3320, B 18. DESIGN OF MACHINE ELEMENTS 26 October words

23 Design project Discussions and tasks to be performed Your first report must include: (Consider visiting an actual site) o Your design objectives & constrains, functional specs (specific to your designs). o Introduction and Background research on Wind Turbines (in general): e.g., historical perspectives, materials used, typical dimensions, efficiencies, design configurations/specifications, operation, etc. (as discussed in class) o FBD s (specific to your designs): identification of geometrical configurations, loading conditions (static and dynamic), assumptions. o Remember: shear, bending, torsion diagrams (main shaft + tower) are next - leave this task as part of next report. Nacelle of a wind turbine: front view Hub of a lowspeed shaft Former ME3320 students Source: Location: Danforth, Maine

24 Design project Discussions and tasks to be performed Identify geometrical configurations & loading conditions (specific to your designs.) Example mechanical configuration Source: Source: Example: low-speed shaft configuration Source: ZENKUNG Co., China

25 Design project Discussions and tasks to be performed Identify geometrical configurations & loading conditions (specific to your designs.) Example shaft /generator configuration Source: Boston Science Museum

26 Reading assignment Chapters 1, 3, and 9 of textbook Review notes and text: ES-2501, ES-2502 Author s: 3-5A, 3-5B, 3-6 Homework assignment Solve: 1-7, 1-8(optional), 3-23(c,h), 3-24(c,h)