1907 4.2 Tensile test This test allows to determine Reduced section 2店 different properties of the 0.505'Diameter 3 Diameter material 2, Usually the sample is Gauge length 3利 Radius deformed to fracture with a gradually increasing tensile load applied uniaxially along the long axis of the specimen Load cell During the test the specimen undergoes an elongation at a constant rate;the instantaneous Extensometer笔 applied load and the elongation of Specimen the specimen are monitored using respectively a load cell and an Moving extensometer. crosshead SINNU-IIALIAIN I CHIVIFUS
SINO-ITALIAN CAMPUS 4.2 Tensile test This test allows to determine different properties of the material Usually the sample is deformed to fracture with a gradually increasing tensile load applied uniaxially along the long axis of the specimen During the test the specimen undergoes an elongation at a constant rate; the instantaneous applied load and the elongation of the specimen are monitored using respectively a load cell and an extensometer
1907 It is necessary to define the stress and deformation independently from the sample geometry;engineering stress and engineering strain are defined as: F 0 二 i-lo_△l Ao lo lo In which: F=instantaneous load l=instantaneous length applied perpendicular to lo=original length before the the specimen cross load is applied section [N] a=unitless (or m/m,or % Ao=original cross sectional area before the load is applied[mm2]o=[MPa] SINO-ITALIAN CAMPUS
SINO-ITALIAN CAMPUS It is necessary to define the stress and deformation independently from the sample geometry; engineering stress and engineering strain are defined as: 𝜎 = 𝐹 𝐴0 𝜀 = 𝑙𝑖−𝑙0 𝑙0 = ∆𝑙 𝑙0 In which: F=instantaneous load applied perpendicular to the specimen cross section[N] A0=original cross sectional area before the load is applied[mm2 ] σ=[MPa] l i=instantaneous length l0=original length before the load is applied ε=unitless (or m/m, or %)
Tension test of low- carbon steel (a】 (b) Apparatus of tension test Tension specimen (a)拉伸前：b拉断后 Schematic representation of tension test
Tension test of low - carbon steel Tension specimen Schematic representation of tension test Apparatus of tension test
应力= Vertical coordinate stress o =F/S o So initial area) Horizon coordinate strain e= (1-10)/10 (1- 一一 terminate length,lo- initial length) stress-strain curve 0 stress,e strain
stress－strain curve Vertical coordinate --- stress σ =F/S 0 （ S0 ---- initial area） Horizon coordinate --- strain ε = (l-l0) /l0 （ l- -- terminate length, l0--- initial length） σ ---- stress,ε ---- strain
应力 应变￡= Elastic deformation:OA Yielding:BC Plastic deformation:C D Necking:DE Fracture:E Deformation in which stress and strain are proportional is called elastic deformation Stiffness:the ability resistant to elastic deformation modulus of Elasticity,E=o/8 The permanent deformation cann't be recovered when external stress is released named plastic deformation
Elastic deformation: OA Yielding: BC Plastic deformation：ＣＤ Necking：DＥ Fracture：E Deformation in which stress and strain are proportional is called elastic deformation. Stiffness: the ability resistant to elastic deformation modulus of Elasticity, E=σ/ε The permanent deformation cann’t be recovered when external stress is released named plastic deformation. 呼