CIVENG 303

Section 804

Stress Concentrations

Performed

October 24th, 2013

Today’s Date:

November 7th, 2013

Tim Hendrickson

OBJECTIVE

The objective of this lab is to determine a set of changes due to the stress in geometric irregularities in an axially loaded bar. Some of the irregularities include certain features such as holes and notches.

QUESTIONS:

-The following are formulas are for stress and strain that are biaxial.

Sample Material

Steel

Testing Machine

INSTRON 3369

Capacity

11K

Measuring Device

Load Cell

1.

a.

b. Poisson’s ratio in the book Mechanics of Materials and Integrated Learning System the calculated value for Structural Steel is 0.26 and our calculated value is 0.196629. This is a difference of 0.063371. This ratio only varies slightly so our values are accurate. In the book the elastic modulus is 29 ksi and ours is 27.219 ksi, which is a difference of 1.781 ksi. Our values seem comparable and accurate.

c. We were asked to calculate the values for the material properties at locations far away from the geometric discontinuities because if the calculations were done on the gages close to the discontinuities, the data would not be a baseline for the material, it would take into account the stress concentrations due to geometric discontinuities.

2. Data Table of Recorded Data

RECORDED DATA

GAGE #

READING W/O LOAD

READING W/ LOADING

UNIAXIAL OR BIAXIAL STRESS εx εy σx(psi) σy(psi)

1

2162

2340

Uniaxial

178

0

4844.982

0

2

2023

1988

Biaxial

0

-35

0

-952.665

3

2607

2767

Uniaxial

160

0

4355.04

0

4

2155

2258

Uniaxial

103

0

2803.557

0

5

1616

2297

Uniaxial

681

0

18536.14

0

6

1976

2664

Uniaxial

688

0

18726.67

0

7

x x x x x x x

8

x x x x x x x

9

1450

1916

Uniaxial

466

0

12684.05

0

10

4150

4591

Uniaxial

441

0

12003.58

0

-The equations that we used to solve this excel table were using