My Exam Notes
  • Home
  • CURRENT AFFAIRS
  • GENERAL AWARENESS
    • Child Category 1
  • BIHAR PSC
  • Home
  • CURRENT AFFAIRS
  • GENERAL AWARENESS
  • BIHAR GK
  • RAJASTHAN GK
  • MECHANICAL NOTES

Tuesday, August 19, 2014

HOOKS LAW AND ELASTIC VS PLASTIC BEHAVIOR OF MATERIAL

 My Exam Notes     8:27 PM     STRENGTH OF MATERIAL     No comments   

     HOOKS LAW : MODULUS OF ELASTICITY

Most engineering structure are designed to undergo relatively small deformations, involving only the straight line portion of the corresponding stress strain diagram. The relation is known as hook's law. The coefficient "E"  is called the modulus of elasticity of the material involved or young's modulus. Since the strain is dimensionless quantity, the modulus "E" is expressed in the same units as the stress namely in pascals or one of its multiples.

Actually at the grass root level if you see that Hook's law is basically the small displacement of atoms and ions of the matter from their actual position due to application of force.

The largest value of stress for which hook's law can be used for a given material is known as proportional limit of that material. In case of ductile materials, the proportional limit almost coincides with the yield point. For outer material proportional limit cannot be determined easily.

MODULUS OF ELASTICITY IS CAN ALSO BE DEFINED AS ability to resist a deformation within the  linear range, in the same.

By bending, twisting, pulling or compressing a material or solid, elasticity can be observed in the material under elastic limit. This is due to hook's law.Consider F= kX where F is the applied force and X is the elongation. k depends on shape,size and type of elastic material. Hook's law is valid for elastic region up to point till force applied is proportional to elongation.

Hook's law can also be written as F= -kX, where F is not the applied force rather it is restoring force which comes in picture when body is coming to its original shape after deformation in elastic bodies. 


ELASTIC VS PLASTIC BEHAVIOR OF MATERIAL
Elastic behavior:-
  • If the strain caused in the test specimen the application of a given load disappear when the load is removed,the material is said to have elastically.
  • The largest value of the stress for which the material behaves elastically is called the ELASTIC LIMIT of the material.
  • Ductile material has well defined yield point, elastic limit, proportional limit.
  • In other words, the material behaves elastically and linearly as long as the stress is kept below the yield point.
Plastic behavior

After the material is stressed or loaded beyond elastic region it can never return to its original shape by itself this is commonly known as plastic deformation. In very simple word we can say that the strain does not return to zero after the load has been removed which indicates that permanent set of plastic deformation of material has taken place. For most of the materials plastic deformation depends not only upon the maximum value reached by the stress, but also upon the time elapsed before the load is removed. Each and every material has different value beyond which plastic deformation occurs.
  • The stress dependent part of plastic deformation is referred to as SLIP. The time dependent part which is also influenced by the temperature is called CREEP.
FATIGUE FRACTURE-BY REPEATED LOADING:-

  • When a specimen is subjected to axial loading and the maximum stress in the specimen does not exceed the elastic limit of material, the specimen return back to the original condition after removing the load.
  • This loading may repeat hundred times or thousand times provided the stress remain in the elastic range.
  • If the loading repeated is of very high order (say million times) the failure may occur at stress much lower than  the static breaking strength this phenomenon is called fatigue.
  • Fatigue failure is brittle in nature. Even ductile material fractures in brittle manner.
  • Fatigue is considered as deigns of all structural member which are subjected to fluctuating or repeated load.
  • Some loading are fluctuating in nature. For e.g. the passage of traffic over bridge is will cause stress levels that will fluctuate about the stress level due to bridge weight.

    • Share This:  
    •  Facebook
    •  Twitter
    •  Google+
    •  Stumble
    •  Digg
    Email ThisBlogThis!Share to TwitterShare to Facebook
    Newer Post Older Post Home

    0 comments:

    Post a Comment

    MY TRAVEL VLOG-Being Tourist

    Popular Posts

    • Environment Current Affairs 2019 PDF download | Important Questions |
      Watch video on EXAM FOCUS YOUTUBE CHANNEL. Which city of china in only one with all electric taxis? Taiyuan Shenzhen Jingia...
    • TURBOMACHINES
                      TURBOMACHINE DEFINATIONAND  EXPLANATION A turbo-machine is a device in which energy transfer takes place between ro...
    • #MOST IMPORTANT AUGUST CURRENT AFFAIRS 2018 #PDF link #NOTES #अगस्त करें...
      PDF IS BELOW NOTES - Go Down Notes of August Current Affairs- Navlekha a new platform launched by Google .Google has announced pr...
    • MAY (1-15th) CURRENT AFFAIRS 2019 | MCQ's | EXPLAINED | FREE PDF |
      PDF WILL BE UPLOADED ON 24/05/2019 The newly elected prime minister of Israel is? Benjamin Netanyahu What is the theme of Internati...
    • #SPACE CURRENT AFFAIRS last 6 months #स्पेस/अंतरिक्ष विज्ञान करेंट अफेयर...
      Indian national committee for space research was established in the year 1962 Indian Space Research Organisation was founded in year 19...
    • BANKING CURRENT AFFAIRS | MD, CEO, CHAIRMAN Of BANKS (UPDATED 2019)| MCQ's | static gk
      This POST is on Banking Awareness 2019 with all important National Banks and its MD/CEO/CHAIRMAN with important points to remember for all...
    • ENERGY LOSS IN PIPES, Darcy- weicbach formula, Chezy's formula, minor losses in pipe
      MECHANICAL TIPS AND STUDY MATERIAL When ever there is flow of fluid in pipes there will be resistance which add to energy loss. For our stud...
    • METAL INERT GAS WELDING AND TUNGSTEN INERT GAS WELDING
              TUNGSTEN INERT GAS WELDING (TIG) CHARACTERISTICS IN  BRIEF It is known as GAS TUNGSTEN ARC WELDING (GTAW). Also called Argon arc wel...
    • ABRASIVE JET MACHINING, WATER JET MACHINING AND ULTRASONIC MACHINING
          ABRASIVE JET MACHINING(AJM) As explained non traditional machining process involves machining action by indirect contact between tool an...
    • ECONOMICS CURRENT AFFAIRS (इकोनॉमिक्स) 2019 | JANUARY- JULY (PART 1)
      PLAY VIDEO AND ENJOY LEARNING PDF AT BOTTOM Which among the following company tied up up with India to issue PAN card? MasterCard Vi...

    Categories

    AUTOMOBILE BASICS BHIHAR PSC BIHAR PSC biology quiz CURRENT AFFAIRS economics FASTEST MACHINES FLUID MECHANICS GEARS GENERAL AWARENESS HEAT AND MASS TRANSFER I C ENGINE JET ENGINES JOB OPENING IN USA MACHINING PROCESSES MANUFACTURING PROCESS MATERIAL SCIENCE mechanical engineering MECHANICAL JOB VACANCY IN INDIA MECHANICAL VIBRATION MISSILES POLITY QUIZ POWER PLANT ENGINEERING RAJASTHAN GK sports STRENGTH OF MATERIAL THERMODYNAMICS TOP COLLEGES TOP SPEED TURBINES WELDING

    Pages

    • QUIZ

    Featured post

    SCIENCE & TECHNOLOGY CURRENT AFFAIRS 2018 (JANUARY - JUNE)विज्ञान प्रौद्...

    CBSE (Central Board of indirect taxes) launched which app to check person collecting GST? GST verify National science day was celebrate...

    ad code

    Copyright © My Exam Notes | Powered by Blogger
    Design by Hardeep Asrani | Blogger Theme by NewBloggerThemes.com | Distributed By blogger Templates