Objective:
\nTo study the behaviour of ductile and brittle materials subject to torsion
\nEquipment:
\n1. Torsion testing machine Tinius Olsen
\n2. Micrometer
\n3. Scale
\nSpecimens:
\nStandard torsion test specimens of steel, aluminum or cast iron
\nProcedure:
\n1. Using the micrometer measure the diameter of specimen to the nearest 0.02 mm at
\nseveral points along the length of the specimen and record the average diameter.
\n2. Check the length of the torsion specimen (200.0 mm).
\n3. Mount specimen in the torsion testing machine. Set the load indicator dial zero.
\n4. Load and\/or deformation increments will be as follows:
\nSteel 56.5 N\uf0d7m (500 in-lb) in the linear range
\n45\uf0b0 in nonlinear range
\nAluminum 33.9 N\uf0d7m (300 in-lb) in the linear range
\n30\uf0b0 in the nonlinear range
\nCast Iron 28.25 N\uf0d7m (250 in-lb) in the linear range
\n5\uf0b0 in the nonlinear range
\n2
\n5. Apply the load slowly by manually operating the machine. Take readings of torque (T)
\nand angle of twist (\uf066) simultaneously, at the specified increments, without stopping the
\nmachine, and carefully record these experimental data.
\n6. When the yield point (for ductile material) is approached (as noted by the increased
\nreadings of angle of twist), the readings of the torque and angle of twist must be
\nobtained more frequently so the stress-strain diagram will be well defined in this
\nvicinity.
\n7. After the yield point (for ductile material) has been exceeded, apply the load until
\nfailure occurs. Readings in this range are based on deformation increments.
\n8. For cast iron, the specimen should be loaded manually until failure occurs.
\n9. Examine the fracture surface, and the type of failure that occurred in each specimen.
\nReport:
\nPrepare your Lab report according to the general instructions provided in the document on
\nStructure & Format of Lab Reports. This is a formal report that should be written using a
\nword processor; the only hand writing allowed is for the sample calculations. Include the
\nfollowing sections a
\n3
\nData Sheet \u2013 Torsion Test
\nMaterial Steel Aluminum Cast Iron
\nType of specimen
\nLength
\n(mm)
\nAverage Diameter
\n(mm)
\nAverage Cross-sectional Area
\n(mm2
\n)
\nProportional Limit in Shear
\n(MPa)
\nYield Point or Yield Strength in
\nShear at 0.001 Radians Offset
\n(MPa)
\nModulus of Rigidity
\n(Shear Modulus) (GPa)
\nUltimate Shearing Stress
\n(MPa)
\nShearing Stress at Rupture
\n(MPa)
\nModulus of Elasticity (Calculated
\nusing \uf06e = 0.30) (GPa)
\n4
\nHints for filling in the data sheet
\nT = torque
\nJ = polar moment of inertia
\n\uf067 = shearing strain
\n\u03c1 = radial distance measured from the axis of the cylindrical specimen (
\n0 \uf0a3 \uf072 \uf0a3 Ro
\n)
\nRo = outside radius of a cylindrical or tubular test piece
\nRi = inside radius of a tubular test piece
\nL = distance between collars of the cylindrical specimen
\n\uf066 = angle of twist (radians)
\n\uf074 = shearing stress
\nG = modulus of rigidity (shear modulus)
\nShearing strain
\nL
\n\uf072\uf066
\n\uf067 \uf03d
\nWithin the proportionality limit,
\nJ
\nT
\nG
\nL
\nG
\n\uf072\uf066 \uf072
\n\uf074 \uf03d \uf067 \uf03d \uf03d
\nFor solid cross sections,
\n4
\n2
\nRo
\nJ
\n\uf070
\n\uf03d
\nFor tubular cross sections,
\n\uf028 \uf029
\n4 4
\n2
\nRo Ri
\nJ \uf03d \uf02d
\n\uf070
\nAdditional hints for filling in the data sheet
\n1. The proportional limit is to be obtained from the shear stress-shear strain curve (enlarged
\ngraph). It is the stress at which the stress-shear strain curve ceases to be linear.
\n2. Yield strength in shear (see figure)
\n5
\n3. Modulus of rigidity (shear modulus)
\nshear strain
\nshear stress G \uf03d
\nIt is the slope of the shear stress-shear stain curve below the proportional limit.
\n4. Ultimate shearing stress =
\nJ
\nT Ro
\n\uf0d7 max
\n(MPa)
\n(assuming the elastic torsion formula holds good up to rupture)
\n5. Shear stress at rupture =
\nJ
\nTrupture Ro
\n\uf0d7
\n(MPa)
\n(assuming the elastic torsion formula holds good up to rupture)
\n6. Modulus of elasticity
\nE = 2G (1 + \uf06e)
\n\uf06e = Poisson\u2019s ratio<\/p>\n","protected":false},"excerpt":{"rendered":"
Mechanics of Deformable Bodies Objective: To study the behaviour of ductile and brittle materials subject to torsion Equipment: 1. Torsion testing machine Tinius Olsen 2. Micrometer 3. Scale Specimens: Standard torsion test specimens of steel, aluminum or cast iron Procedure: Read More …<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15],"tags":[],"class_list":["post-436619","post","type-post","status-publish","format-standard","hentry","category-essay-paper-writing"],"_links":{"self":[{"href":"https:\/\/www.benedictsol.com\/blogs\/wp-json\/wp\/v2\/posts\/436619","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.benedictsol.com\/blogs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.benedictsol.com\/blogs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.benedictsol.com\/blogs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.benedictsol.com\/blogs\/wp-json\/wp\/v2\/comments?post=436619"}],"version-history":[{"count":0,"href":"https:\/\/www.benedictsol.com\/blogs\/wp-json\/wp\/v2\/posts\/436619\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.benedictsol.com\/blogs\/wp-json\/wp\/v2\/media?parent=436619"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.benedictsol.com\/blogs\/wp-json\/wp\/v2\/categories?post=436619"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.benedictsol.com\/blogs\/wp-json\/wp\/v2\/tags?post=436619"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}