Impact Test Procedure PDF

**Object:** To conduct the impact test and determine the impact strength if mild/aluminium specimen by (a) Izod method (b) Charpy method **Equipment/Apparatus:** - Impact Testing - Izod and Charpy test specimens of mild steel/aluminium - Vernier caliper **Impact strength and significance...

**Object:** To conduct the impact test and determine the impact strength if mild/aluminium specimen by (a) Izod method (b) Charpy method **Equipment/Apparatus:** - Impact Testing - Izod and Charpy test specimens of mild steel/aluminium - Vernier caliper **Impact strength and significance of Impact test:** The impact test is done to test the toughness of a material. Toughness is the property which enables the material to be twisted, bent or stretched under a high stress before rupture. Toughness takes into account both the strength and ductility of the material. The impact test simulates the service conditions often encountered in transportation, agriculture and construction equipment which are frequently subjected to impact and shock loads during sudden blows and stopages. The stresses induced during impact loading are many more times the stress induced during gradual loading. Impact tests are essentially performed to assess shock absorbing capacity of materials subjected to suddenly applied loads. Toughness is indicated by the amount of energy that a unit volume of the material could absorb after being stressed upto the point of fracture, it is expressed in Nm. Of all types of impact tests, the notched bar tests are most extensively used. The impact test then measures the energy necessary to fracture a standard notch by applying an impulse load. **Impact Testing Machine:** Impact testing machine takes the form of a pendulum which is made to strike a sudden blow against the test specimen. The pendulum swinging down from a specified height hits the test piece and the height to which it rises after striking depends on the energy absorbed in breaking the test piece. Greater the energy absorbed in breaking lower is the height to which the pendulum rises. A scale is provided to measure the energy absorbed during the impact test. **Test Specimen:** Both in the Izod and Charpy impact tests, the specimen is in the form of notched beam as shown in fig. In Izod test, the specimen is kept as cantilever beam while in Charpy test it is placed as simply supported beam. The specimen have V-shaped of 45 degree and the depth of notch is generally taken as t/5 to t/3 where t is the thickness of specimen. **Test Procedure:** \(i) Get the specimen made as per appropriate length, angle of notch and its depth \(ii) Bring the striking hammer to its top most position and lock it at that position. \(iii) Press down the pendulum release lever so that the hammer falls and swings past the bottom most position. Note down the reading (say x) on the dial. This initial reading is without any specimen and indicates the air and frictional loss in the energy of the hammer. \(iv) Bring the hammer again to its top most position and lock it at that position. \(v) Clamp the test specimen in the vice. For izod test, the notch should face the striking hammer and be half inside and half above the top surface of the vice. For Charpy test, the specimen is placed on supports or anvil so that the blow of hammer is opposite to that of notch. \(vi) Release the striking hammer. The hammer would strike the test specimen and fracture it. The total energy of the hammer will not be absorbed and it will swing to the other side of the specimen. At its topmost height after breaking the specimen, note down the indicator reading (say y). \(vii) Make use of brake handle to stop the motion of hammer after its swing. \(viii) Repeat the experiment an other similar test specimens. **Observations:** Material of test piece = Dimension of test piece = length× breadth×height Type and angle of notch = V- notch, 45-degree Depth of notch = Specimen No. 1 2 ------------------------------ --- --- Reading without specimen (x) Reading with specimen(y) Impact strength, U = (x-y) Result: The impact strength of the given specimen is...........Nm. Precautions: \(i) Get the specimen prepared in proper dimensions. \(ii) The specimen should be firmly and securely gripped in the vice. \(iii) For Charpy test, the specimen should be so located that the hammer strikes it at the middle \(iv) The longitudinal axis of specimen should be lie in the plane of swing of the centre of gravity of hammer. C:\\Users\\DELL\\Desktop\\B TECH 1ST YR 22-23\\lab manual BME Lab\\WhatsApp Unknown 2022-10-02 at 9.21.21 PM\\WhatsApp Image 2022-10-02 at 9.24.21 PM.jpeg  C:\\Users\\DELL\\Desktop\\B TECH 1ST YR 22-23\\lab manual BME Lab\\WhatsApp Unknown 2022-10-02 at 9.21.21 PM\\WhatsApp Image 2022-10-02 at 9.25.15 PM.jpeg