Name: Fatigue Test.
Aim: To observe the effect of combined hundreds (bending & torsion) on rotating contributors through testing a sample specimen as shown beneath of the identical cloth so as to be utilized in design. Two principal factors is studied on this test is the fatigue energy and fatigue lifestyles.
Theory: Due to the variable, repeated, alternating, or fluctuating stresses, such device individuals are discovered to have failed under the movement of repeated or fluctuating stresses and this failure is called a fatigue failure . it has an appearance similar to a brittle fracture , as the fracture surfaces are flat and perpendicular to the strain axis with the absence of necking . The fatigue failure phenomenon is surely represented for positive type of metal in determine beneath between fatigue strength and logarithmic fatigue existence.
Procedure
1- measure the dimensions of the metal pattern specimen [RF 1010] and connect it within the Rotating Fatigue device.
2- move the adjustable dead load weight along the burden arm to select a suitable load for the specimen fabric. (50 N for the metallic sample (RF 1010), 20 N for aluminum pattern (RF 1020))
3- Slowly flip the motor accelerate until the cycle rate is 60 Hz (+\ _ 1 Hz).
4- file the cycle fee. Record the neck electricity at existence’s (one hundred,one thousand, step of 5000) cycle.
5- whilst the specimen breaks, report the cycle rely.
Sample RF 1010 [Steel BS 970 230M07]:
Tensile electricity = 460 MPa, Yield electricity = 310 MPa
Pattern RF 1020 [Aluminum Alloy 2011 T6]:
Tensile energy = 395 MPa, Yield strength = 220 MPa [Min.]
Sample RF 1010 [Brass Alloy CZ 121]:
Tensile power = 460 MPa, Yield power = 310 MPa
Calculation
& Discussion:
1- Calculate the theoretical static neck pressure for the adjusted load in object .
2- Draw the everyday S – N curve for the above mentioned specimens, and then point out the actual duty factors of the examined samples [actual stress for each life cycle].
3- For the metallic specimen, comment on the gotten consequences if the specimens are operating inside the persistence lifestyles or failure had passed off. What is the fracture existence?
4- Specify the elements that affect the fatigue lifestyles (increasing or decreasing).
5- what is the importance of doing such test for the substances?
