A term paper on the effects of vibration on the mechani cal properties of engineering materials
A TERM PAPER ON THE EFFECTS OF VIBRATION ON THE MECHANI CAL PROPERTIES OF ELECTRICAL GENERATING PARTS BY GROUP 12 ADEBOLU, IBUKUN O. (MEE/06/8076) ASHAJU, ABIMBOLA S. (MEE/06/8096) AYOADE, J.ADEKOLA (MEE/06/8099) ADEBAYO ADEDAMOLA (MEE/06/8074) BALOGUN KAYODE (MEE/04/3052) IBEH CHUKWUEBUKA (MEE/06/8116) AFOLABI OLUMIDE FESTUS (MEE/06/8083) SUBMITTED TO ENGR. P.K. OKE DEPARTMENT OF MECHANICAL ENGINEERING, FEDERAL UNIVERSITY OF TECHNOLOGY, AKUREIN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE COURSE MEE 403, THEORY OF MACHINES II MARCH, 2O1O.
1.0 OBJECTIVETo investigate the impact of Vibration on the Mechanical Properties of Electrical Generating Parts(Cylindrical Rods)2.0 INTRODUCTIONVibration is the study of oscillatory motion that occurs in dynamic system and the forces associatedwith these motion. Mechanical properties of a material include its tensile strength, toughness,ductility, hardness, brittleness, elasticity, resilience, malleability etc.Electrical generating parts are devices used in the generation of electrical energy by mechanicalactuated motions. In this case, a generating set was used. In this work, we shall be investigating theimpact of vibration on the cylindrical rods of the generating set. The cylindrical rod was tested forits hardness 2
3.0 THEORYVibration has a number of effects on engineering materials which could be positive and beneficialor negative and undesirable.The advantages of vibration can be found in the sorting of grains into different sizes or grades andin the deliberate weathering of rocks.The disadvantages of vibration are; it causes wear and tear in mechanical parts and it causes totalbreakdown of the system if resonance occurs.The effective performance of a machine depends on the vibrating characteristics of the machine.The effect of vibration on the hardness of engineering materials, cylindrical rods in this case, isinvestigated in this work. It is assumed that vibrations have a cumulative effect on the internalstructures of the engineering parts involved thus having a consequent action on the mechanicalproperties of cylindrical rods. The nature of this effect is investigated by comparing measuredvalues with standard values.There are a number of different techniques of measuring hardness. The knoop, Brinell, Vickers,Mohs, and Rockwell methodologies are employed; but for the purpose of this work, the Rockwellmethod of hardness test is carried out.The digital Rockwell Hardness testing machine was used in this experiment. Of the two types ofindenters that can be used (cone and ball), a 1/16 inch ball type indenter was used with a V-anvil. 3
MACHINES / APPARATUS USED I. Digital Rockwell Hardness Testing Machine; the values obtained were class ‘F’ (HRF) because the indenter used was the 1/16 inch ball indenter. II. Emery paper; its function is to level the surface to be tested and to remove rusts or metallic oxides from the surface of the test piece. III. Electrical generating set; the generating set used was one supposed to have been subjected to vibration (in this case, it was used to power photocopying machines). The generator was dismantled and the cylindrical rod (test piece) was chosen from the parts.4.0 PRACTICAL PROCEDURE 1. The old part (rod) is polished with emery paper to remove rusts and smoothen the surface of the part. 2. The V-anvil and 1/16 inch ball indenter were attached to the Rockwell hardness testing machine and the rod was rightly placed in between the V-anvil and indenter. 3. The device was adjusted so that the screen read “1” with a corresponding beep sound. 4. The screen displayed the first hardness value and it was recorded. 5. The rod was shifted so that another point could be tested. The value was also recorded. 6. The average of the two values was calculated and compared to the standard Rockwell hardness value of mild steel. 4
5.0 EXPERIMENTAL SET-UP DIGITAL ROCKWELL HARDNESS TESTING MACHINE 5
6.0 RESULTS Rockwell hardness value for Old Cylindrical rods 99.6 HRF (60 kg) 97.9 HRF (60 kg) Average 98.75 HRF (60 kg) Standard /ideal Rockwell hardness value of mild steel (which is the parent material of the rod) is 109.5 HRF (60 kg) (http://www.carbide-stldepot.com/formulas-hardness.htm)DISCUSSIONThe result obtained from the experiment (98.75 HRF (60 kg) for the old cylindrical rod) iscompared with the Rockwell hardness value of ideal mild steel (109.5 HRF (60 kg)). The hardnessvalue of the rod is less than the ideal value of mild steel. It is therefore safe to assume that thehardness value of the unused part is more than the part that has been subjected to vibration amongother reasons. The effect of vibration in this case, is negative since the rigidity of the system willalso decrease with the hardness of the parts until the eventual breakdown of the system.PRECAUTIONS 1. The part (cylindrical rod) to be tested was smoothened using emery paper to level the surface and to remove the oxides (rust) formed on the surface so that the actual hardness value is obtained and not the hardness of the rust. 2. The lower screw of the testing machine was tightened slowly while the rod was mounted on it so as to minimize error. 3. The rod was balanced horizontally on the anvil also to minimize error.7.0 CONCLUSION 6
The major objective of this work was to investigate the effect of vibration on the mechanicalproperties of electrical generating parts. From the research work done, it can be concluded that thehardness of the connecting rods reduced because of the negative impact of vibrations on the systemamong other reasons. Thus, we can easily infer that vibrations reduce the hardness of engineeringmaterials rendering them more ductile and less satisfactory to the design criteria, hence leading tothe eventual breakdown of the system. 7