# Mechanics of Materials Engr 350 - Lecture 1

Mechanics of Materials Engr 350 - Lecture 1 Stress - Normal/Direct shear Mechanics of Materials Study of internal effects caused by external loads Considers real bodies that deform (statics assumes no deformation) 3 main concerns Strength - Will it _____________________?

Stiffness - Will it _____________________? Stability - Will it ______________________? 2 Stress Defined as the intensity of an internal force In equation form: stress forc = e Note: scalar - just a number area vector - quantity with magnitude and direction tensor - has magnitude & direction as well as a plane

Stress is a tensor First subscript is the direction of area normal Second subscript is direction of the stress component 3 Normal Stress Use method of sections to consider a rectangular

bar with an axial load We cut a section through the bar Now the whole cut surface is resisting the load 4 Normal stress

The stress is acting normal to the cut surface therefore it is called a normal stress We use the symbol for normal stress for normal stress Sign convention for normal stress Positive (tension): Negative (compression): 5 Stress Example Determine the stress in the concrete pilar

6 Two-bar loading How to find load carried by each bar? Sum x and y forces at

joint Two equations, three unknowns Why not sum moments? Calculate F1,allowable based on max stress and area Solve for F2 and P based on F1,allowable Check if F2 is higher or lower than F2,allowable If necessary, repeat using F2,allowable to solve for F1 and P 7 Demo TK Solver?

Use the following: A1 = 2.0 in2 A2 = 1.5 in2 for normal stress1,max = 12,000 psi for normal stress2,max = 18,000 psi At the joint, what are these equations? FFx = 0 FFy = 0 What are the max allowable forces for F1 and F2?

8 Stress on inclined plane (TB Section 1.5) What if we cut the bar at an angle? What stresses are acting on that surface? 9

## Recently Viewed Presentations

• Easy Chair uses the term " SuperChair " to refer to conference/congress program chairpersons. Track Chairs are not SuperChairs. Conference Program Chairs or the VP of programs authorizes the release of official Accept/Reject notices through the
• Arial Calibri Courier New Wingdings Sample presentation slides(2) White with Courier font for code slides 1_Sample presentation slides(2) 2_Sample presentation slides(2) 3_Sample presentation slides(2) Ecclesiastes 3:1-8 Ecclesiastes 3:1-8 "Redeeming the Time" "Redeeming the Time" "Redeeming the Time" Time Obligations Hosea...
• 2.17 describe how experiments involving the reactions of elements such as copper, iron and phosphorus with air can be used to determine the percentage by volume of oxygen in air. Experiment with copper. This can be demonstrated by the reactionof...
• In early May 1915, shortly after losing a friend in Ypres, a Canadian doctor, Lt Col John McCrae was inspired by the sight of poppies to write a now famous poem called 'In Flanders Fields'. McCrae's poem inspired an American...
• They match the traditional model,but varying them can result in alternative "models" e.g. never replace paper equivalent to functional programming. Note: often tempted to say "take" value from a box and do something with it,however, this gives impression box is...
• Dr Kerry Hempenstall, RMIT University What determines professional practices? Superstition? Folklore? Craft? Science? Superstition Unsubstantiated world views derived from intuition or legend. Galileo first observed moons around Jupiter in 1610. His observations were derided.
• Management and the New Confucianism. Presenters: Marko, Kasia, Rasa, Victor and DJ Park. ... Samsung: Change everything and become a first class company ... 1. To serve the customer 2. Respect people 3. Create value - Bottom-up approach to decision...
• Context Clues: You be the Detective by Mrs. Renee Garner Context Clues - What Are They? Context clues are bits of information from the text that, when combined with prior knowledge, allow you to decide the meaning of unknown words...