a Course, College, country
b Course, College, country
Abstract
Tensile strength is a kind of force which is applied by pulling something such as rope, wire etc. to the point where it breaks [1]. The tensile strength of the material is the maximum amount of tensile stress that it can take before failure [1]. There is different kind of tensile strength yield strength, ultimate strength, breaking strength. The tensile strength can be found using tensile test which is a kind of the mechanical test [2]. Tensile test are simple, inexpensive and fully standardized. The motto of this paper is to analyze the tensile strength of different material and providing results based on different tensile strength of various materials.
Keywords: Pull, Tensile stress, Tensile test, Mechanical test, Materials
1. Introduction
The tensile strength of various materials can be determined using tensile test. The tensile testing is also known as tension testing, which is a fundamental material science in which a sample is subjected under a failure [3]. The results for its test is targeted to select a material for various applications in the view of quality control, and to predict how a material will react under other type of faces. There are some properties which are directly measure under tensile test; they are ultimate tensile stress, maximum elongation and reduction in area. The following properties are measured using the tensile strength, young’s modulus, Poisson ratio, yield strength and strain hardening [4]. The tensile strength of different materials varies based on its breaking capacity. The purpose of making tensile strength is to select the material for the different applications. The tensile testing is used to determine the behavior of a sample while an axial stretching load is applied. The tensile testing is performed on the various materials including metals, plastics, elastomers, paper, adhesive, films etc. The common tensile testing results include, maximum load, deflection of the maximum load, work at the maximum load, stiffness, stress, strain, young’s modulus etc. The results are compared for different metals and the best suited applications are chosen based on the different tensile strength. The tensile strength on the different metals is already calculated the analysis and report has to be prepared based on the tensile strength of the required materials [4]. The materials with the best suited tensile strength are highlighted. The typical tensile strength depends on yield strength, ultimate strength and density [4].
2. Materials
The tensile test are predicted for the various materials like norm steel, BM steel, HDPE,. The The high density polyethylene is a polyethylene thermo plastic made from petroleum. The HDPE is commonly used in the production of plastic bottles [7]. The HDPE is known ratio. The density of the high density poly ethylene can range from 0.93 to 0.99. BM steel is designed for the application where common anti corrosion coating are hot sufficient. The BM steel is used in an environment conductive to corrosion and in processes which cannot tolerate particle generation from anti corrosion coating [8]. The different materials have different properties and tensile strength. Selecting a material for a particular application is based on the tensile strength and properties of the material used.
3. Experimental Procedure
The tensile test is widely used type of test which can provide complete information on the properties of the material [9]. There are some influential categories in the tensile testing is calculating yield strength, tensile strength, young’s modulus, toughness of the material, resilience etc. The tensile test gives a basic structure for a material; it is used for choosing different materials for different application [9].
The specimen is placed in the machine and the force is applied until the specimen fractures. The three important things are necessary in this process are speed, accuracy and precision. The enough force should be applied to make the specimen to fracture. The corresponding measurements are been taken [9]. The initial reading is noted before test. The proper load scale should be selected in order to fracture the specimen quickly [9].
According to the load type, there are two kinds of tensile testing machines.
- Screw Driven testing In Screw driven testing machine elongation rate is kept constant [9].
- Hydraulic Testing Machines Hydraulic testing machines keep the loading rate constant. The loading rate can be set depending on the desired time of fracture [9].
A tensile load is applied to the specimen until it fractures: The load required to make a certain elongation on the material is recorded. A load elongation curve is plotted by an X-Y recorder, so that the tensile behavior of the metal can be obtained.
The Engineering stress is obtained by the load by the original area of the cross section.
Stress σ=p/AO (Load/ Initial cross sectional area)
Strain σ= ∆1/lo (Elongation/ initial gage length)
The tensile strength is the maximum stress that the material can support.
σuts=Pmax/Ao
The tensile strength is easy to determine and it is quite reproductive property. For brittle materials the tensile strength is a valid criterion for design [9].
Yield strength is a stress level at which plastic deformation starts. The beginning of the first plastic deformation is yielding. The 0,2% offset method is commonly used method to determine the yield strength [9].
Resilience is the capacity of the material to absorb energy when it’s deformed elastically. The toughness is measure of energy required to cause fracture [9].
Poisson ratio is the lateral contraction per unit breadth divided by the longitudinal extension [9].
V = - (∆ddo)/(∆llo)
Young’s modulus is also called as the extensional modulus is a measure of stiffness of the elastic isotropic material. Young’s modulus is defined as E = Tensile stress/ Extensional Strain
E= σ/∈
Procedure
Before Test
- Put the gage mark on the specimen, 2. Mark the initial gage reading and diameter, 3. Select the load scale to deform and fracture the specimen
During Test
- Record the maximum load, 2. Continue test until fracture
After Test
1. Measure the gage length and diameter; the diameter should be measured from the neck.
The accuracy: repeatability and precision of tensile tests can only be quantified when know quantities are measured. One difficulty of assessing data is that no agreed upon “material Standards” exist as reference materials with known properties of the strength and elongation. The system accuracy and repeated experiments would quantify its precision and repeatability. The factors affecting accuracy are sources of errors like instrumental errors, testing errors and material errors [9].
- Results on the Tested Materials
The norm metal has the yield strength ranges from 470 Mpa, UTS ranges from 680 Mpa, failure ranges from 550 Mpa, young’s modulus ranges from 210 Gpa, %el ranges from 20% and %ra ranges from 50%.The variation in values on the different days is depends on various errors that affects precision and accuracy. The BM steel has the yield strength of 470 Mpa, UTS of 665 Mpa; failure of 460 Mpa, young’s modulus of 215 Gpa, %el of 10 %, %ra of 59%. The HPDE has the no yield strength, the UTS is about 27 Mpa, failure of 14 Mpa, %el of 14.7 %, %ra 95%.
The norm has good yield strength compare the other tested materials; norm steel has good plastic deformation. The ultimate tensile strength of norm steel is good and it can support large amount of stress. The fracture rate of norm steel yields high value. Norm steel has excellent elongation rate (Young’s Modulus E). %el ranges from 20-33% and %ra ranges from 50-71 The BM steel has moderate yield strength compare the other tested materials, BM steel has low plastic deformation. The ultimate tensile strength of BM steel is better and it can support moderate amount of stress. The fracture rate of BM steel is moderate. BM steel has better elongation rate (Young’s Modulus E). %el ranges from %el of 10 – 13%, %ra of 48-63.5%. The HDPE has no yield strength compare the other tested materials, HDPE has no plastic deformation. The ultimate tensile strength of HDPE is fair and it can support low amount of stress. The fracture rate of HDPE is low. HDPE has no elongation rate (Young’s Modulus E). %el ranges from 325 – 670% and % ra ranges from 95 -96 %.
- Conclusion
The tested materials has different tensile strength, it varies largely. The accuracy and precision of the tested materials is better any how the much more accuracy is needed to judge the exact properties of the tested metal. The tension test experiments give more detailed information of the materials. The detailed information is required to select the tested material for the different application. The tension testing gives the various properties of the different materials and their complete nature in different environment. The main motto of doing tensile test is to know the modulus of elasticity, elastic limit, elongation, tensile strength, yield strength etc. The different, materials gives different tensile strength is depends on stress Vs strain [10]. The stress and strain value of the each and every material varies which makes the material different from one another in tensile strength [10].
References
[1] Wikipedia, 2009, Tensile Testing. Web. 17 Dec 2013. Available at: http://simple.wikipedia.org/wiki/Tensile_strength. 28 Dec 2013
[2] Chatillon, 2011, Tensile testing. Web. Available at: http://www.chatillon.com/test-solutions/test-types/tensile-strength-testing.aspx. 28 Dec 2013
[3] Wikipedia, 2009, Tensile Testing. Web, 17 Dec 2013. Available at: http://en.wikipedia.org/wiki/Tensile_testing. 28 Dec 2013
[4] Instron, 2011, Tensile Testing. Web. Available at: http://www.instron.in/wa/applications/test_types/tension/default.aspx. 28 Dec 2013
[5] Wikipedia, 2009, Aluminium. Web. 17 Dec 2013 Available at: http://en.wikipedia.org/wiki/High-density_polyethylene. 28 Dec 2013
[6] Wikipedia, 2009, Nylon. Web. 17 Dec 2013 Available at: http://en.wikipedia.org/wiki/Nylon. 28 Dec 2013.
[7] Wikipedia, 2009, HDPE. Web 17 Dec 2013. Available at: en.wikipedia.org/wiki/High-density_polyethylene. 28 Dec 2013.
[8] Schneeberger, BM stainless steel. Web. Available at: http://www.schneeberger.com/fileadmin/images/produkte/monorail/Monorail_BM_Edelstahlausfuehrung_rostfrei.pdf. 28 Dec 2013.
[9] Prof Dr Riza, Tension Test. Web. Available at: http://ocw.metu.edu.tr/pluginfile.php/1216/mod_resource/content/0/Tension_Test_-_ekme_Deneyi.PDF. 28 Dec 2013
[10] NDT resource center, 2011, Tensile properties. Available at: http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Mechanical/Tensile.htm. 28 Dec 2013
