.he *l!min!m and teel am+les 7ere meas!red and recorded for f!rther calc!lations at the end of the lab tartin/ 7ith the al!min!m sam+le strain /a!/es 7ere +laced on the sam+le and the location of each strain /a!/e 7as recorded for calc!lations .he cylindrical sam+le 7as +laced into M. .estin/ machine 7ith the ball bearin/ +laced in the center slot .he ball bearin/ 7as ali/ned 7ith the center of the M. machine 9irst a 125 :ilo ne7ton load 7as a++lied and the strain 7as recorded from each /a!/e then a 25 :ilo ne7ton load 7as a++lied and a/ain the strain 7as recorded .he +ress!re 7as then relieed from the sam+le and the ball bearin/ 7as remoed from the center slot to the 2& millimeter slot Both loads 7ere re-a++lied and the strain 7as recorded .he +ress!re 7as once a/ain relieed from the sam+le and the ball bearin/ 7as remoed and +laced into the 25 millimeter slot both loads 7ere re-a++lied and the strain 7as recorded for both load al!es .he al!min!m sam+le 7as then re+laced 7ith the steel sam+le and the +roced!res aboe 7ere then re+eated
Results &lu"inu"
2
20 mm Eccentricity Aluminum, 12.5 kN 5 0 -50
-40
-30
-20
-10
0
10
20
30
40
50
-5 -10
Stress (MPa) -15 -20 -25 -30
Distance (mm)
3
20mm Eccentricity Aluminum, 25 kN 10 0 -50
-40
-30
-20
-10 -10 0
10
20
30
40
50
-20
Stress (MPa)
-30 -40 -50 -60
Distance (mm)
25 mm Eccentricity Aluminum, 12.5 kN 10 0 -50
-40
-30
-20
-10
0
10
20
30
40
50
-10
Stress (MPa) -20 -30 -40
Distance (mm)
4
25 mm Eccentricity Aluminum, 25 kN 20 0 -50
-40
-30
-20
-10
0
10
20
30
40
50
-20
Stress (MPa) -40 -60 -80
Distance (mm)
Steel
5
am+le in M. Machine
20 mm Eccentricity Steel, 12.5 kN 5 0 -50
-40
-30
-20
-10
-5 0
10
20
30
40
50
-10
Stress (MPa)
-15 -20 -25 -30
Distance (mm)
6
20mm Eccentricity Steel, 25 kN 20 0 -50
-40
-30
-20
-10
-20
0
10
20
30
40
50
Stress (MPa) -40 -60 -80
Distance (mm)
25 mm Eccentricity Steel, 12.5 kN 10 5 0 -50
Stress (MPa)
-40
-30
-20
-10 -5 0
10
20
30
40
50
-10 -15 -20 -25 -30 -35
Distance (mm)
7
25 mm Eccentricity Steel, 25 kN 10 0 -50
-40
-30
-20
-10 -10 0
10
20
30
40
50
-20
Stress (MPa)
-30 -40 -50 -60 -70
Distance (mm)
Discussion
9rom the res!lts aboe it can be seen that steel handles ;!ite 7ell !nder eccentric load com+ared to *l!min!m $t 7as calc!lated that the mod!l!s of elasticity for steel 7as 2&,"11 at 125 :< 7hile al!min!m had an "lastic mod!l!s of ,"1& 7hich is si/nificantly less $t can be seen that steel is a clear choice 7hen eccentric loadin/ is a main factor *lso the lar/est +ercent error al!e obtained d!rin/ the lab 7as 18= 7hile the smallest al!e of +ercent error 7as &1&4= >hile 18= is a lar/e amo!nt of error the lab 7as ;!ite s!ccessf!l other7ise * +otential so!rce of error co!ld be the fact that the cylindrical s+ecimen 7as not +laced in the direct center of the M. Machine .his co!ld affect the strain readin/s since the machine is a++lyin/ +ress!re at the 7ron/ +oint *nother +otential so!rce of error co!ld be 7ithin the strain /a!/es themseles >hile recordin/ the strain /a!/e readin/s from the lab com+!ter the strain readin/s did not sto+ fl!ct!atin/ $f a readin/ had fl!ct!ated /reatly this co!ld affect f!rther calc!lations d!rin/ the lab *nother so!rce of error co!ld be deformation in the cylindrical sam+les themseles $f the cylinder had deformed d!rin/ the e?+eriment it 7o!ld ca!se the sam+les to hae different characteristics than e?+ected 'onclusion
.herefore the aera/e stress al!e of al!min!m at 125:< 7as 1251 M6a and at 25:< 7as 24, M6a .he aera/e stress al!e of teel at 125 :< 7as 12'8 M6a 7hile at 25 :< it 7as 245 M6a
