Tensile Testing: Methodology, Results, And Data Analysis

1. Consider what can go wrong
2. Determine how bad the outcome would be - Consequences
3. Determine how likely it is to happen - Likelihood
4. Calculate the risk level 

Tensile testing is a standout amongst the most key tests for building, and gives valuable data about a material and its related properties. These properties can be utilized for plan and examination of designing structures and for developing new materials that better suit a predefined use.

The tensile testing laboratory was conducted using a load frame and the six distinct materials were tested, including Annealed steel, Poly vinyl chloride (PVC), copper, polymethylmethacrylate (PMMA) and tempered steel. The examples were rectangular in cross segment, with a decreased gage area. The reduce gage segment guaranteed that the most elevated burdens happened inside the gage, and not close to the grasps of the heap outline, avoiding strain and crack of the example close or in the holds. The examples were at that point machined to the correct measurements required for the test, as indicated by ASTM gauges.

Three examples of every material were tried in the load frame, and the information accumulated into an Excel spreadsheet. The information was utilized to compute tensile property of every material. The data was then plotted on engineering stress-strain curves to compare the samples. The reason for this investigation was to assemble data about every material so imperative mechanical properties could be resolved. This test likewise acclimated the understudies with the load frame that was utilized and the general strides to playing out a malleable test on a diminished gage area example.

Every example was estimated with the calipers to decide the measurement of the cross segment. A gage length was resolved (50.00 mm) and scribed into the example with the goal that the separation between the two imprints could be estimated after the elastic test was finished. Normal lessened gage segment examples are appeared in Figure 1. The Lab see information procurement programming was begun, and the right material was picked. The heap cell was focused to guarantee that the product just estimated the malleable load connected to the example.

The samples were stacked into the jaws of the Instron load frame with the goal that it was similarly divided between the two clasps. The hub and transverse extensometers were joined to the decreased gage area of the example, guaranteeing that the pivotal extensometer was set effectively while appending it to the gage and that the transverse extensometer was over the total measurement of the example. This precautionary measure brings about better information and forestalls harm to the extensometers.

Answer:

The Instron load frame, appeared in Figure 2 was preloaded utilizing the parchment wheel to guarantee that the sample was legitimately loaded on the frame, and that it wasn't slipping in the jaws. The load was discharged, and the extensometers were focused utilizing the Lab view programming. The test was begun, and the sample was loaded, bringing about a quantifiable strain. For the steel and copper tests, the crosshead was at first set to move upward at 1.25 mm/min, at that point at 15 mm/min at a predefined state past yielding. This expansion in the rate of strain accelerated the test, however may have likewise presented some blunder. The poly vinyl chloride (PVC) test began at 5 mm/min and was later accelerate to 30 mm/min. The PMMA tests were pulled at a steady rate of 10 mm/min.

The information was accumulated utilizing the product, and stacked into a spreadsheet. At a set estimation of strain (past the yield strain), the product prevented utilizing information from the extensometers, and began gathering the strain data utilizing the situation of the moving crosshead. A notice message came up on the PC screen, educating the administrator to expel the extensometers to avert harm. The test proceeded until break, where the product ceased the moving crosshead, and completed the process of social affair information. The example was expelled, and the crosshead was reset to the underlying position to begin another ductile test. The testing method was rehashed for whatever remains of the examples.

The data from the tensile tests was plotted on independent diagrams as indicated by material. Each graph shows the engineering stress versus the engineering strain, as figured per Appendix A. table 1 demonstrates the normal tests for the Annealed steel tests, and table 2 demonstrates the normal pliable trial of the copper tests. Table 3, table 4, table 5 and table 6 demonstrated the test consequences of the PVC, PMMA, tempered steel and plywood, separately.

strain	stress	strain * stress	(stress-mean)	square	staim*square value
0	350	0	-102.37	10479.62	0
0.025	320	8	-132.37	17521.82	438.0454225
0.05	360	18	-92.37	8532.217	426.610845
0.055	400	22	-52.37	2742.617	150.8439295
0.06	450	27	-2.37	5.6169	0.337014
0.075	480	36	27.63	763.4169	57.2562675
0.075	490	36.75	37.63	1416.017	106.2012675
0.1	500	50	47.63	2268.617	226.86169
0.125	510	63.75	57.63	3321.217	415.1521125
0.15	520	78	67.63	4573.817	686.072535
0.175	520	91	67.63	4573.817	800.4179575
0.2	520	104	67.63	4573.817	914.76338
0.25	500	125	47.63	2268.617	567.154225
0.35	300	105	-152.37	23216.62	8125.815915
1.69		764.5			12915.53256
		mean = 764.5/1.69
		= 452.37
		standard deviation  = sqroot(square*square value)/(N-1)
		= sqroot(12915.53256/1.69-1)
		= 136.81

Graphical presentation

Data and calculation

average strain (m/m)	average stress (Mpa)	strain*stress	strss-mean	square	strain*square
0	0	0	-319.96	102374.4	0
0.01	150	1.5	-169.96	28886.4	288.864016
0.012	300	3.6	-19.96	398.4016	4.7808192
0.015	360	5.4	40.04	1603.202	24.048024
0.02	350	7	30.04	902.4016	18.048032
0.02	370	7.4	50.04	2504.002	50.080032
0.03	360	10.8	40.04	1603.202	48.096048
0.06	360	21.6	40.04	1603.202	96.192096
0.09	360	32.4	40.04	1603.202	144.288144
0.1	365	36.5	45.04	2028.602	202.86016
0.12	350	42	30.04	902.4016	108.288192
0.13	320	41.6	0.04	0.0016	0.000208
0.15	300	45	-19.96	398.4016	59.76024
0.18	250	45	-69.96	4894.402	880.992288
0.937		299.8			1926.298299
	mean = 299.8/0.937  319.96
	standard deviation = sqroot( 1926.2983/0.937)  = 45.34

Table 2

Data and calculation

strain	stress	strain*stress	stress - mean	square	strain*square
0	0	0	-51.44	2646.074	0
0.05	20	1	-31.44	988.4736	49.42368
0.1	60	6	8.56	73.2736	7.32736
0.12	60	7.2	8.56	73.2736	8.792832
0.2	45	9	-6.44	41.4736	8.29472
0.2	48	9.6	-3.44	11.8336	2.36672
0.25	46	11.5	-5.44	29.5936	7.3984
0.4	47	18.8	-4.44	19.7136	7.88544
0.6	47	28.2	-4.44	19.7136	11.82816
0.8	48	38.4	-3.44	11.8336	9.46688
1	49	49	-2.44	5.9536	5.9536
1.2	52	62.4	0.56	0.3136	0.37632
1.4	60	84	8.56	73.2736	102.58304
6.32		325.1			221.697152
	mean = 325.1/6.32 = 51.44
	standard deviation = sqroot(221.697/6.32-1) = 6.46

Table 3

strain	stress	strain*stress	strss-mean	square	strain*square
0	0	0	-66.52	4424.91	0
0.005	10	0.05	-56.52	3194.51	15.972552
0.01	30	0.3	-36.52	1333.71	13.337104
0.02	50	1	-16.52	272.9104	5.458208
0.025	60	1.5	-6.52	42.5104	1.06276
0.035	65	2.275	-1.52	2.3104	0.080864
0.04	70	2.8	3.48	12.1104	0.484416
0.045	75	3.375	8.48	71.9104	3.235968
0.05	80	4	13.48	181.7104	9.08552
0.23		15.3			48.717392
		mean = 15.3/0.23=66.52
		standard deviation = sqroot( 48.72/0.23) = 14.55

Table 4

Data and calculation

strain	stress	strain*stress	stress -mean	square	strain*square
0	300	0	-102.37	10479.62	0
0.025	270	6.75	-132.37	17521.82	438.0454225
0.05	310	15.5	-92.37	8532.217	426.610845
0.055	350	19.25	-52.37	2742.617	150.8439295
0.06	400	24	-2.37	5.6169	0.337014
0.075	430	32.25	27.63	763.4169	57.2562675
0.075	440	33	37.63	1416.017	106.2012675
0.1	450	45	47.63	2268.617	226.86169
0.125	460	57.5	57.63	3321.217	415.1521125
0.15	470	70.5	67.63	4573.817	686.072535
0.175	470	82.25	67.63	4573.817	800.4179575
0.2	470	94	67.63	4573.817	914.76338
0.25	450	112.5	47.63	2268.617	567.154225
0.35	250	87.5	-152.37	23216.62	8125.815915
1.69		680			12915.53256
		mean = 680/1.69 = 402.37
		standard deviation = sqroot(12915.53/0.69)= 136.81

Table 5

strain	stress	strain * stress	stress-mean	square	strain*square
0	0	0	-41.44	1717.274	0
0.05	10	0.5	-31.44	988.4736	49.42368
0.1	50	5	8.56	73.2736	7.32736
0.12	50	6	8.56	73.2736	8.792832
0.2	35	7	-6.44	41.4736	8.29472
0.2	38	7.6	-3.44	11.8336	2.36672
0.25	36	9	-5.44	29.5936	7.3984
0.4	37	14.8	-4.44	19.7136	7.88544
0.6	37	22.2	-4.44	19.7136	11.82816
0.8	38	30.4	-3.44	11.8336	9.46688
1	39	39	-2.44	5.9536	5.9536
1.2	42	50.4	0.56	0.3136	0.37632
1.4	50	70	8.56	73.2736	102.58304
6.32		261.9			221.697152
		mean = 261.9/6.32=41.44
		standard deviation = sqroot(221.70/5.32) = 6.46

Table 6Material Properties 

The ultimate tensile strength for each material is recorded in Table 7. The estimation of a ultimate tensile strength was discovered utilizing the procedure in Appendix B. The strain relating to a ultimate tensile strength is where necking begins to occur..

Sample material	Ultimate tensile strength, u (MPa)	Standard deviation (MPa)
Anneal steel	520	136.81
PVC	60	6.46
Plywood	50	6.46
PMMA(Acrylic)	75	14.55
Copper	365	45.34
Tempered steel	470	138.81

Table 7: The ultimate tensile strength for the six materials.

One sample of copper was used to find the true stress and the true strain encountered during a tensile test, and to compare both to the engineering stress and the engineering strain. The engineering stress and strain does not represent the adjustment in cross sectional territory, and records for the hub strain in the example. The true strain represents the adjustment in cross sectional area, than the engineering strain due to strains in the transverse direction along the gage of the sample

Methodology

The test results were consistent for each of the materials, as evident in graph 1 to graph 6. An interesting observation can be made from the PMMA graph, where sample one suddenly loses stress as it is stretched. This sample may have fractured partially across the cross section before complete failure, or a void could have caused a sudden release of stress. All of the other samples exhibited consistent behavior.

From the ultimate tensile strength data in Table 7, it is clear that the Annealed steel was the strongest material, followed by tempered steel, copper, PMMA, PVC and plywood, respectively. All of the standard deviations were moderately low, not exceeding 150 MPa, suggesting that the data was consistent and that the testing procedure was valid and repeatable.

Reference

Meyers,MA & Chawla,KK 2009, Mechanical behavior of materials, 2nded, Cambridge University Press, Cambridge and New York.

MIT Open Courseware 2007, Guidelinesfor Writing a Lab Report, viewed1 December 2016, .

Drury, H 1997, How to write a laboratory report, Learning Centre, University of Sydney, Sydney.

Foecke, T 1998, Metallurgy of the RMS Titanic, US Department of Commerce, Technology Administration, National Institute of Standards and Technology, Materials Science and Engineering Laboratory.

Callister, WD & Rethwisch, DG 2014, Materials science and engineering: an introduction, 9th edn, Wiley,HobokenNJ.

Standards Australia 2003, AS 1544.2–2003 Method forimpact tests on metals Part 2: Charpy V-notch, standards, viewed 3 February 2017

Chapra,SC&Canale,RP2010,Numericalmethodsforengineers,6thedn,McGraw-HillHigherEducation, Boston.

Akin H, Tugut F, Guney U, Kirmali O and Akar T. Tensile bond strength of silicone-based soft denture liner to two chemically different denture base resins after various surface treatments. Lasers in Medical Science. 2013; 28(1):119-123. https://dx.doi. org/10.1007/s10103-012-1082-7. PMid:22447403.

Bolay?r G, Demir H, Do?an A, Boztu? A, Murat Do?an O and Soygun K. Effects of different high alkyl methacrylate monomers on tensile bond strength between resilient liner and acrylic resin. Materials Research Innovations. 2009; 13(4):431-435. https://dx.doi.org/10.1179/143289109X12494867167288.

El-Hadary A and Drummond JL. Comparative study of water sorption, solubility, and tensile bond strength of two soft lining materials. The Journal of Prosthetic Dentistry. 2000; 83(3):356- 361. https://dx.doi.org/10.1016/S0022-3913(00)70140-5. PMid:10709046.

Tensile testing is a standout amongst the most key tests for building, and gives valuable data about a material and its related properties. These properties can be utilized for plan and examination of designing structures and for developing new materials that better suit a predefined use.

The tensile testing laboratory was conducted using a load frame and the six distinct materials were tested, including Annealed steel, Poly vinyl chloride (PVC), copper, polymethylmethacrylate (PMMA) and tempered steel. The examples were rectangular in cross segment, with a decreased gage area. The reduce gage segment guaranteed that the most elevated burdens happened inside the gage, and not close to the grasps of the heap outline, avoiding strain and crack of the example close or in the holds. The examples were at that point machined to the correct measurements required for the test, as indicated by ASTM gauges.

Procedure

Three examples of every material were tried in the load frame, and the information accumulated into an Excel spreadsheet. The information was utilized to compute tensile property of every material. The data was then plotted on engineering stress-strain curves to compare the samples. The reason for this investigation was to assemble data about every material so imperative mechanical properties could be resolved. This test likewise acclimated the understudies with the load frame that was utilized and the general strides to playing out a malleable test on a diminished gage area example.

Every example was estimated with the calipers to decide the measurement of the cross segment. A gage length was resolved (50.00 mm) and scribed into the example with the goal that the separation between the two imprints could be estimated after the elastic test was finished. Normal lessened gage segment examples are appeared in Figure 1. The Lab see information procurement programming was begun, and the right material was picked. The heap cell was focused to guarantee that the product just estimated the malleable load connected to the example.

The samples were stacked into the jaws of the Instron load frame with the goal that it was similarly divided between the two clasps. The hub and transverse extensometers were joined to the decreased gage area of the example, guaranteeing that the pivotal extensometer was set effectively while appending it to the gage and that the transverse extensometer was over the total measurement of the example. This precautionary measure brings about better information and forestalls harm to the extensometers.

The Instron load frame, appeared in Figure 2 was preloaded utilizing the parchment wheel to guarantee that the sample was legitimately loaded on the frame, and that it wasn't slipping in the jaws. The load was discharged, and the extensometers were focused utilizing the Lab view programming. The test was begun, and the sample was loaded, bringing about a quantifiable strain. For the steel and copper tests, the crosshead was at first set to move upward at 1.25 mm/min, at that point at 15 mm/min at a predefined state past yielding. This expansion in the rate of strain accelerated the test, however may have likewise presented some blunder. The poly vinyl chloride (PVC) test began at 5 mm/min and was later accelerate to 30 mm/min. The PMMA tests were pulled at a steady rate of 10 mm/min.

Results

The information was accumulated utilizing the product, and stacked into a spreadsheet. At a set estimation of strain (past the yield strain), the product prevented utilizing information from the extensometers, and began gathering the strain data utilizing the situation of the moving crosshead. A notice message came up on the PC screen, educating the administrator to expel the extensometers to avert harm. The test proceeded until break, where the product ceased the moving crosshead, and completed the process of social affair information. The example was expelled, and the crosshead was reset to the underlying position to begin another ductile test. The testing method was rehashed for whatever remains of the examples.

figure 1: Reduced gage section specimen made from Annealed steel, ready for tensile testing.

Figure 2 A typical Instron load frame used for tensile testing.

The data from the tensile tests was plotted on independent diagrams as indicated by material. Each graph shows the engineering stress versus the engineering strain, as figured per Appendix A. table 1 demonstrates the normal tests for the Annealed steel tests, and table 2 demonstrates the normal pliable trial of the copper tests. Table 3, table 4, table 5 and table 6 demonstrated the test consequences of the PVC, PMMA, tempered steel and plywood, separately.

strain	stress	strain * stress	(stress-mean)	square	staim*square value
0	350	0	-102.37	10479.62	0
0.025	320	8	-132.37	17521.82	438.0454225
0.05	360	18	-92.37	8532.217	426.610845
0.055	400	22	-52.37	2742.617	150.8439295
0.06	450	27	-2.37	5.6169	0.337014
0.075	480	36	27.63	763.4169	57.2562675
0.075	490	36.75	37.63	1416.017	106.2012675
0.1	500	50	47.63	2268.617	226.86169
0.125	510	63.75	57.63	3321.217	415.1521125
0.15	520	78	67.63	4573.817	686.072535
0.175	520	91	67.63	4573.817	800.4179575
0.2	520	104	67.63	4573.817	914.76338
0.25	500	125	47.63	2268.617	567.154225
0.35	300	105	-152.37	23216.62	8125.815915
1.69		764.5			12915.53256
		mean = 764.5/1.69
		= 452.37
		standard deviation  = sqroot(square*square value)/(N-1)
		= sqroot(12915.53256/1.69-1)
		= 136.81

Table 1

Graphical presentation

Graph 1: The engineering stress versus the engineering strain for Annealed steel.

Data and calculation

average strain (m/m)	average stress (Mpa)	strain*stress	strss-mean	square	strain*square
0	0	0	-319.96	102374.4	0
0.01	150	1.5	-169.96	28886.4	288.864016
0.012	300	3.6	-19.96	398.4016	4.7808192
0.015	360	5.4	40.04	1603.202	24.048024
0.02	350	7	30.04	902.4016	18.048032
0.02	370	7.4	50.04	2504.002	50.080032
0.03	360	10.8	40.04	1603.202	48.096048
0.06	360	21.6	40.04	1603.202	96.192096
0.09	360	32.4	40.04	1603.202	144.288144
0.1	365	36.5	45.04	2028.602	202.86016
0.12	350	42	30.04	902.4016	108.288192
0.13	320	41.6	0.04	0.0016	0.000208
0.15	300	45	-19.96	398.4016	59.76024
0.18	250	45	-69.96	4894.402	880.992288
0.937		299.8			1926.298299
	mean = 299.8/0.937  319.96
	standard deviation = sqroot( 1926.2983/0.937)  = 45.34

Table 2

Graphical presentation

Graph 2: The engineering stress versus the engineering strain for copper.

Data and calculation

strain	stress	strain*stress	stress - mean	square	strain*square
0	0	0	-51.44	2646.074	0
0.05	20	1	-31.44	988.4736	49.42368
0.1	60	6	8.56	73.2736	7.32736
0.12	60	7.2	8.56	73.2736	8.792832
0.2	45	9	-6.44	41.4736	8.29472
0.2	48	9.6	-3.44	11.8336	2.36672
0.25	46	11.5	-5.44	29.5936	7.3984
0.4	47	18.8	-4.44	19.7136	7.88544
0.6	47	28.2	-4.44	19.7136	11.82816
0.8	48	38.4	-3.44	11.8336	9.46688
1	49	49	-2.44	5.9536	5.9536
1.2	52	62.4	0.56	0.3136	0.37632
1.4	60	84	8.56	73.2736	102.58304
6.32		325.1			221.697152
	mean = 325.1/6.32 = 51.44
	standard deviation = sqroot(221.697/6.32-1) = 6.46

Table 3

Graphical presentation

Graph 3: The engineering stress versus the engineering strain for PVC.

Data and calculation

strain	stress	strain*stress	strss-mean	square	strain*square
0	0	0	-66.52	4424.91	0
0.005	10	0.05	-56.52	3194.51	15.972552
0.01	30	0.3	-36.52	1333.71	13.337104
0.02	50	1	-16.52	272.9104	5.458208
0.025	60	1.5	-6.52	42.5104	1.06276
0.035	65	2.275	-1.52	2.3104	0.080864
0.04	70	2.8	3.48	12.1104	0.484416
0.045	75	3.375	8.48	71.9104	3.235968
0.05	80	4	13.48	181.7104	9.08552
0.23		15.3			48.717392
		mean = 15.3/0.23=66.52
		standard deviation = sqroot( 48.72/0.23) = 14.55

Table 4

Graphical presentation

Graph 4: The engineering stress versus the engineering strain for PMMA (Acrylic).

Data and calculation

strain	stress	strain*stress	stress -mean	square	strain*square
0	300	0	-102.37	10479.62	0
0.025	270	6.75	-132.37	17521.82	438.0454225
0.05	310	15.5	-92.37	8532.217	426.610845
0.055	350	19.25	-52.37	2742.617	150.8439295
0.06	400	24	-2.37	5.6169	0.337014
0.075	430	32.25	27.63	763.4169	57.2562675
0.075	440	33	37.63	1416.017	106.2012675
0.1	450	45	47.63	2268.617	226.86169
0.125	460	57.5	57.63	3321.217	415.1521125
0.15	470	70.5	67.63	4573.817	686.072535
0.175	470	82.25	67.63	4573.817	800.4179575
0.2	470	94	67.63	4573.817	914.76338
0.25	450	112.5	47.63	2268.617	567.154225
0.35	250	87.5	-152.37	23216.62	8125.815915
1.69		680			12915.53256
		mean = 680/1.69 = 402.37
		standard deviation = sqroot(12915.53/0.69)= 136.81

Table 5

Graphical presentation

Graph 5: The engineering stress versus the engineering strain for Tempered steel.

Data and calculation

strain	stress	strain * stress	stress-mean	square	strain*square
0	0	0	-41.44	1717.274	0
0.05	10	0.5	-31.44	988.4736	49.42368
0.1	50	5	8.56	73.2736	7.32736
0.12	50	6	8.56	73.2736	8.792832
0.2	35	7	-6.44	41.4736	8.29472
0.2	38	7.6	-3.44	11.8336	2.36672
0.25	36	9	-5.44	29.5936	7.3984
0.4	37	14.8	-4.44	19.7136	7.88544
0.6	37	22.2	-4.44	19.7136	11.82816
0.8	38	30.4	-3.44	11.8336	9.46688
1	39	39	-2.44	5.9536	5.9536
1.2	42	50.4	0.56	0.3136	0.37632
1.4	50	70	8.56	73.2736	102.58304
6.32		261.9			221.697152
		mean = 261.9/6.32=41.44
		standard deviation = sqroot(221.70/5.32) = 6.46

Table 6

Graphical presentation

Graph 6: The engineering stress versus the engineering strain for plywood.

The ultimate tensile strength for each material is recorded in Table 7. The estimation of a ultimate tensile strength was discovered utilizing the procedure in Appendix B. The strain relating to a ultimate tensile strength is where necking begins to occur..

Sample material	Ultimate tensile strength, u (MPa)	Standard deviation (MPa)
Anneal steel	520	136.81
PVC	60	6.46
Plywood	50	6.46
PMMA(Acrylic)	75	14.55
Copper	365	45.34
Tempered steel	470	138.81

Data and Calculation

Table 7: The ultimate tensile strength for the six materials.

One sample of copper was used to find the true stress and the true strain encountered during a tensile test, and to compare both to the engineering stress and the engineering strain. The engineering stress and strain does not represent the adjustment in cross sectional territory, and records for the hub strain in the example. The true strain represents the adjustment in cross sectional area, than the engineering strain due to strains in the transverse direction along the gage of the sample

The test results were consistent for each of the materials, as evident in graph 1 to graph 6. An interesting observation can be made from the PMMA graph, where sample one suddenly loses stress as it is stretched. This sample may have fractured partially across the cross section before complete failure, or a void could have caused a sudden release of stress. All of the other samples exhibited consistent behavior.

From the ultimate tensile strength data in Table 7, it is clear that the Annealed steel was the strongest material, followed by tempered steel, copper, PMMA, PVC and plywood, respectively. All of the standard deviations were moderately low, not exceeding 150 MPa, suggesting that the data was consistent and that the testing procedure was valid and repeatable.

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