tafila technical university

Faculty engineering

Experiment 2 Compression test

Name: Salam Fayez Albaradie

Lecturer name: Dr.Tamer Alshaqarin

Date of submission: 9/3/2014

1. Introduction

Compression tests are used to determine how a product or material reacts when it is compressed, squashed,

crushed or flattened by measuring fundamental parameters that determine the specimen behavior under a

compressive load. These include the elastic limit, which for "Hooke an" materials is approximately equal

to the proportional limit, and also known as yield point or yield strength, Young's Modulus (these,

although mostly associated with tensile testing, may have compressive analogs) and compressive strength.

Compression tests can be undertaken as part of the design process, in the production environment or in the

quality control laboratory, and can be used to:

Assess the strength of components e.g. automotive and aeronautical control switches, compression

springs, bellows, keypads, package seals, PET containers, PVC / ABS pipes, solenoids etc.

Characterize the compressive properties of materials e.g. foam, metal, PET and other plastics and

rubber

1.1 Objective To determine the compressive strength of given sample

To determine the modules of elasticity

1.2 Benefits of Compression Testing

Compression testing provides data on the integrity and safety of materials, components and products,

helping manufacturers ensure that their finished products are fit-for-purpose and manufactured to the

highest quality.

The data produced in a compression test can be used in many ways including:

To determine batch quality

To determine consistency in manufacture

To aid in the design process

To reduce material costs and achieve lean manufacturing goals

To ensure compliance with international and industry standards

1.3 Applications of Compression Testing

Compression testing is used to guarantee the quality of components, materials and finished products within

wide range industries. Typical applications of compression testing are highlighted in the following

sections on:

Aerospace and Automotive Industry

Construction Industry

Cosmetics Industry

Electrical and Electronic Industry

Medical Device Industry

2. Theory

Stress-strain diagrams for compression have different shapes from those for tension. Ductile materials

such as steel, aluminum and brass have proportional limits in compression very close to those in tension.

Therefore the initial regions of their compression stress-strain diagrams are very similar to the tension

diagrams. However, when yielding begins, the behavior is quite different. In a tensile test, the specimen is

stretched, necking may occur, and fracture ultimately takes place. When a small specimen of ductile

material is compressed, it begins to bulge outward on the sides and become barrel shaped. With increasing

load, the specimen is flattened out, thus offering increased resistance to further shortening (which means

the stress-strain curve goes upward). These characteristics are illustrated below, which shows a

compression stress-strain diagram for copper.

Brittle materials in compression typically have an initial linear region followed by a region in which the

shortening increases at a higher rate than does the load. Thus, the compression stress-strain diagram has a

shape that is similar to the shape of the tensile diagram. However, brittle materials usually reach much

higher ultimate stresses in compression than in tension. Also, unlike ductile materials in compression,

brittle materials actually fracture or break at the maximum load. The tension and compression stress-strain

diagrams for a particular type of cast iron are given in Figure 1.

Figure 1. The tension and compression stress-strain diagrams for a particular type of cast iron

3. Calculation And Figures

3.1. Figures

Figure 2 true stress vs. strain

3.2. Calculation

Modules of elasticity (E) =

From the figure the slope of the line is

and it’s (E) equal to (0.266775±1.2%) (Gpa).

y = 0.2668x - 11.651 R² = 0.9934

-20

0

20

40

60

80

100

120

140

160

0 100 200 300 400 500 600

stre

ss (

mp

a)

strain (mm/mm)

3.3. Sample of calculation

Force (N) Deformation (10^-3) Stress (mpa)

Strain (mm/mm)

0 2 0 0.2

0 9 0 0.9

95 686 1.326445127 68.6

99 691 1.382295448 69.1

120.5 720 1.682490924 72

176 772 2.45741413 77.2

187.5 780 2.617983803 78

199 789 2.778553477 78.9

513.5 935 7.169784976 93.5

1368.5 1277 19.10779112 127.7

1373.5 1279 19.17760402 127.9

1378 1280 19.24043563 128

1382.5 1281 19.30326724 128.1

1382.5 1282 19.30326724 128.2

1387 1284 19.36609886 128.4

1391.5 1285 19.42893047 128.5

1975 1486 27.57609606 148.6

1979.5 1487 27.63892767 148.7

1979.5 1489 27.63892767 148.9

1984 1490 27.70175929 149

1988.5 1491 27.7645909 149.1

1993 1492 27.82742251 149.2

1997.5 1494 27.89025412 149.4

1997.5 1495 27.89025412 149.5

2002.5 1496 27.96006702 149.6

2007 1499 28.02289863 149.9

10104.5 5517 141.0848925 551.7

4. conclusions

In this experiment, we have seen how the response of the sample with a Compression force

acting on them; was the type specimen of aluminum; we find that the closest relationship to

be linear between stress and strain.