Engr 121 – Mechanics of Materials Fall 2007 Skeleton Class Notes Professor Brian Weick What is Mechanics of Materials? –Relationships are studied between external forces on a deformable body and the intensity of internal forces or stress acting within the body. –Deformations of the body are computed, and the stability of the body due to the external forces is studied. Approach: –Use Statics to determine forces acting on and within members of a structure. –Material behavior needs to be understood to develop necessary equations. –Many design equations and codes are based on principles of Mechanics of Materials.

Topics Studied in Engr Mechanics of Materials Statics – review Stress Strain Mechanical Properties of Materials Axial Loading Torsion Bending Shear Combined Loading Stress Transformation Beam & Shaft Deflection Beam Design Buckling of Columns Failure Theories – intro.

Collapsed Bridge outside Minneapolis, Minnesota Relevance of Mechanics of Materials A Bridge Being Inspected in Tennessee

Principles learned in Mechanics of Materials are applied in these applications too nano.sandia.gov

Analysis serves Design From a Mechanics of Materials Viewpoint: Design involves determining functional characteristics of structures, machine parts, and other devices that include but are not limited to aesthetics, geometry, ergonomics, economics, marketability, manufacturability, recyclability, environmental impact, etc. The Engineering Design process often involves starting with a a vague set of Needs and Objectives that lead to alternative Concepts. These Concepts are in turn narrowed down to a single Configuration that leads to a Detailed Design. Analysis serves Design by providing engineers with valuable skills that they can use to analyze their ideas and determine if they meet important Objectives related to internal forces and their impact on stress and strain levels that could compromise safety, and/or lead to deformation, or undesirable deflection of structures, machine parts, and other devices. Analysis also leads to the development of standard, often proprietary designs owned by companies, as well as national standards or codes such as AISC Codes, Building Codes, & ASME Boiler & Pressure Vessel Codes.

Approach to Learning Mechanics of Materials Understand fundamental principles by attending class, listening to the lectures, reading the text, and taking notes. Try to read through the text sections before class, then take notes in class, and re-read the text section after class while embellishing your notes. Apply fundamental principles to physical situations through examples performed in class and in the text. Then, work through homework problems on your own. Initiate before you ask for help! Do not work in a group until you have initiated the problem on your own. Once you have a basic understanding of the problem, you can consult with others if for some reason you get stuck. Remember that you will be tested on your knowledge of principles and ability to apply them without the benefit of a group.

Course Website The website for the ________ Engr 121 course is located at ______________________________________________________________ Information that can be found at the website: Course Overview Policies Syllabus Annotated Lecture Notes Engineering Analysis Formats Homework Solutions

Engineering Analysis Format Standard Methodologies for Analyzing & Solving Engineering Problems Students are expected to use a solution methodology to analyze and solve engineering problems. As described at the Engr 121 website, the Long Solution Format can be used for complex problems, and the Short Solution Format can be used for simpler problems. Solution formats such as these are actually used by engineers in industry. The headings might be slightly different, but the format is typically the same. Additional sections might even be added such as a References section that will reference any associated drawings, manuals, or other analyses. Note that the solution formats are intended to guide your thinking. You must use engineering paper when analyzing and solving engineering problems. Use a soft-lead pencil (F or HB). Place your name at the top of each sheet in the left-hand box, and staple your homework at the top left-hand corner. Number each page at the top right-hand corner. The center block at the top of the page is often used by a checker or supervisor as needed to sign-off on the analysis.

Units & Significant Figures Review your Physics and Statics texts for information about units and significant figures. USCS (U.S. Customary System) – commonly called the “English” system. Systéme International d’Unités – commonly called the “metric” or S.I. system.