11-29-10 Drill

1. 11-29-10 Drill • A single iron rod, radius R, has a critical buckling load B and a tensile fracture force Tmax= T • If you bond together seven such rods in the following two configurations, what will be their new failure loads? Explain your answers. a) b)

2. Additional Problems • ASTM A36 steel has an ultimate tensile strength of 400 MPa and a Young’s Modulus of 200 GPa. If you create 1 m long rods of the following configurations, what will be their critical buckling and tensile fracture loads? Ro = 2 cm Ri = 1 cm R = 1 cm R = 2 cm A B C R = 1 cm D

3. How would you solve for these two configurations?

4. With a 5% uncertainty in each measured value, what is the uncertainty that propagates through your calculations to your final answers?

5. Now at a cost of $1 per pound and a density of 7.8 g/cm3, what is the difference in costs among the four configurations? Ro = 10 cm Ri = 7.5 cm R = 1 cm R = 2 cm R = 1 cm

6. Materials Test Wednesday • Anything covered in lecture and lab • A couple error/uncertainty problems • Multiple choice, matching, short answer

7. Materials Review Objectives Review major concepts from materials lecture and materials lab Understand the implications of material properties and tension/compression equations on design

8. Review PowerPoint “U2-2 Materials 2”