1.5-2 A bar of length 2.0 m is made of a structural steel having the stress-strain diagram shown in the figure. The yield stress of the steel is 250 MPa and the slope of the ini- tial linear part of the stress-strain curve (modulus of elas- ticity) is 200 GPa. The bar is loaded axially until it elongates 6.5 mm, and then the load is removed. How does the final length of the bar compare with its original length? (Hint: Use the concepts illustrated in Fig. 1-36b.) o (MPa) 300 200 100 0.002 0.004 0.006

3. The bar shown below is composed of two pieces, AC and CD. The bar is attached to the wall at point A. The length L = 10 in. The cross sectional areas are: AAC = 4 in? and AcD = 2 in?. The Young's Moduli are: EAC =20 Msi and Ecd= 15 Msi Two forces are applied at points B and D: PB = 50 kips and PD = 20 kips. Determine: (a) the reaction force at A (specify –→ or +) and (b) the deflection of point D (specify → or +). (Hint for (b): Think about how many pieces you must subdivide the rod into.) Ans: RA = 30 kips (+), dp = 7.9167×10-3 in (E) A В C D Pp L 2L L

A solid steel bar 250 mm long is 10 mm square over part of its length, the remainder being circular with a diameter of 25 mm. A gradually applied tensile load P kN induces maximum stress in the bar of 200 MPa. The total strain energy in the bar when this stress of 200 MPa  is acting is 1,3 Joule. Take E = 200 GPa   Calculate : The load The length of the square portion of the bar The load that falls from a height of 8 mm and induces 1,3 Joules in the bar

Consider the steel truss and member cross-section presented in figures below. All the members of the truss have the same cross-section as shown in the figure to the right. They all also have a Young's Modulus of 210 GPa. What can the highest value of force F be before member AC fails by buckling? Force 1AN - 300 mm 40° 4 m $35 mm 7m 300 mm 8 m 35 mm 35 mm 35 mm Please provide your answer in kN.