ü Most commonly the specimen lies on a span and the load is applied to the centerby the loading nose producing three point bending at a specified rate. üThe parameters for this test are : +The support span; +The speed of the loading +The maximum deflection for the test. These parameters are based on the test specimen thickness, and are defined differently by ASTM and ISO. Specimen Size: üA variety of specimen shapes can be used üThe most commonly used specimen size: + 3.2mm x 12.7mm x 125mm for ASTM D790 +10mm x 4mm x 80mm for ISO 178 Test Procedure: Flexural test üFlexural strength üFlexural modulus Flexural test b b L F δ 3 3 4 hb Lm E b = 2 2 3 hb LF b =σ m : initial slope of the load vs. deflection curve For relatively thin samples → two point loading For thick samples → 4 point loading Flexural test Izod Impact Testing (Notched Izod) üNotched IzodImpact is a single point test that measures a materials resistance to impact from a swinging pendulum. ü Izodimpact is defined as the kinetic energy needed to initiate fracture and continue the fracture until the specimen is broken. üIzodspecimens are notched to prevent deformation of the specimen upon impact. üThis test can be used as a quick and easy quality control check to determine if a material meets specific impact properties or to compare materials for general toughness. Scope: ü 64 x 12.7 x 3.2 mm for ASTM D256 üThe preferred thickness is 6.4 mm because it is not as likely tobend or crush üThe depth under the notch of the specimen is 10.2 mm ü80 x 10 x 4 mm forISO 180 üThe depth under the notch of the specimen is 8mm Specimen Size: Izod Impact Testing (Notched Izod) üThe specimen is clamped into the pendulum impact test fixture with the notched side facing the striking edge of the pendulum. üThe pendulum is released and allowed to strike through the specimen. üIf breakage does not occur, a heavier hammer is used until failure occurs. üSince many materials (especially thermoplastics) exhibit lower impact strength at reduced temperatures ⇒ to test materials at temperatures that simulate the intended end use environment izodimpact.wmv Izod Impact Testing (Notched Izod) Test Procedure: üThe specimens are conditioned at the specified temperature in a freezer until they reach equilibrium. üThe specimens are quickly removed, one at a time, from the freezer and impacted. üNeither ASTM nor ISO specify a conditioning time or elapsed timefrom freezer to impact -typical values from other specifications are 6 hours of conditioning and 5 seconds from freezer to impact. Reduced Temperature Test procedure: ASTM üImpact energy is expressed in J/m or ft-lb/in. üImpact strength is calculated by dividing impact energy in J (orft-lb) by the thickness of the specimen. üThe test result is typically the average of 5 specimens. ISO üImpact strength is expressed in kJ/m 2 üImpact strength (a cU )is calculated by dividing impact energy in J by the area under the notch. Data 3 cU 10a ×= bh W W: energy b = width of the sample h = thickness of the sample üThe test result is typically the average of 10 specimens. The higher the resulting number, the tougher the material. . toughness. Scope: ü 64 x 12.7 x 3.2 mm for ASTM D256 üThe preferred thickness is 6 .4 mm because it is not as likely tobend or crush üThe depth under the notch of the specimen is 10.2 mm ü80 x 10 x 4 mm forISO. 12.7mm x 125mm for ASTM D790 +10mm x 4mm x 80mm for ISO 178 Test Procedure: Flexural test üFlexural strength üFlexural modulus Flexural test b b L F δ 3 3 4 hb Lm E b = 2 2 3 hb LF b =σ m :. the load vs. deflection curve For relatively thin samples → two point loading For thick samples → 4 point loading Flexural test Izod Impact Testing (Notched Izod) üNotched IzodImpact is a single