# Introduction to Principal Stresses and Plane – Principal Stresses and Planes – Strength of Materials

Hello friends here we are starting a new chapter in sum and the name of the chapter is Principal Stresses and Planes it is called as principal stresses in plains sometimes we even call it as principal stresses and strains now when we are talking about principal stresses and Plains first I’ll give an example that here there is a plane plane has negligible thickness next here I will assume that along X Direction there is a stress called as Sigma X which is of tensile nature then along Y there is stress Sigma Y which is again of tensile nature so now I will say that for this figure a body or a plane may be subjected to only normal stress now normal stress means either tensile or compressive stress so you’re the example one which I have given in this a plane is subjected to stress stresses along two perpendicular directions that is along x and y along X the stress is Sigma X along Y it is Sigma Y and they are called as normal stresses so a plane may be only subjected to normal stress next if I consider the same plane call it as a b c and d and now instead of normal stress it can happen that the nature of the stresses would be like this in two opposite directions that is the first stress is acting upward on the face ad next a stress is acting in downward direction on Phase BC I will call it as tau so this indicates shearing action because in case of shear one of the force would be acting in one direction other should act in the opposite direction because of that there is shearing action so here on phase ad the shear stress or I can say the shear force is acting along upward direction on BC it is acting along the onward direction because of that there would be shearing or sliding of this plane next similarly now because of this sliding I can say that this is clockwise shear the other thing possible is that one phase a B there can be shear stress acting towards left tau then on phase DC there can be a shear stress acting towards right so because of that this is called as the anti clockwise shear first it was clockwise shear again there is shearing action so I can say that a body or a plane may be subjected to only shear stress the other word of shear stress is tangential stress now in this example here the body is acted upon only by shear stress previously it was subjected to only normal stress so here we have seen what is meant by normal stress and shear stress next there can even be a case where we have normal as well as shear stress so I can say that again drawing the diagram lene ABCD now here I say that Sigma X is acting along X Direction Sigma Y is the stress along y direction now this is a case of normal stress then apart from that there is even shear stress shear forces are acting on Phase ad on phase BC next there is even shear stress acting along a b and acting along DC so the third case I can write it down as a body or a plane may even be subjected to a combination of normal stress as well as tangential stress which is also called as shear stress so now as I have started the introduction of this chapter by explaining that how the stresses are acting on different planes so in this chapter we are going to see such cases in which normal stress shear stresses would be acting along plane sometimes the plane may even be inclined and we have to find out the values of stresses on that inclined plane so here in this chapter some notations would be used that is tensile or compressive stresses given in the problem that is in the Delta in the problem would be denoted by Sigma X or Sigma Y or it can be opposite of Y Server so now here I have written an important point that in the chapter of principal stresses and planes tensile or compressive stresses given in the problem that is in the data they will be they would be denoted by Sigma X or Sigma Y next shear stress or I can say the tangential stress stress will be denoted by Sigma suffix T now whenever I write Sigma suffix T in this chapter it would be tangential stress and not tenderized stress because if it is tensile or compressive we can denote it directly by Sigma X for Sigma Y so these are some special notations which would be used in this chapter so your in this video we have seen the introduction of the chapter of principal stresses and planes

## 73 comments on “Introduction to Principal Stresses and Plane – Principal Stresses and Planes – Strength of Materials”

1. Sabin Chand Post author

2. Kunal kapoor Post author

im having question that why thickness is not considered. if any particle is their thickness should be there. without thickness its practically impossible. practically it can not exist.

3. Ekeeda Post author

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4. Subscribe for Subscribe Post author

sir hindi me visdeo send kriye kyu hm diploma valo ko samgh ni ata plz sir

5. Vikram Manhas Post author

Sir plz can u upload a video of mohr's circle …and …some problem based on mohr's circle

6. SaiSrinivas Reddy Post author

Sir principal stress is acting on which plane and shear stress is acting on which plane …say me answer sir

7. Vishal Rathod Post author

Can u upload principal stress and principal planes subject to stresses at a particular point in 3d situation for i want 1 sloved sum on this

8. SEARCHY TECH Post author

What is this plane in beams can you explain which plane is it beams or flexural members and what about z axis or span

9. Kuldeep kumar Post author

You just write the definition of that particular term where is concept man???
Could please tell me that what is principal plane and principal stresses and what are their importance and why and when we we have to consider these stresses??

10. Deepak Kumar Sonkar Post author

if a mohr circle is drawn for a fluid element inside a fluid body at rest it would be ??explain?

11. MITHUN SANJAY KARANJE Post author

12. Purushotam Bowrisetty Purushotam Post author

And stresses on an inclined plane under different uniaxial and biaxial stress

13. Pratyusha Sahu Post author

Ham video esliye dekhte hain kyun ki ham wo samajh nahi pate or agar ap sirf answer kahoge toh Kay hoga sry sir galat mat samajhna???

14. jagdish Chandra joshi Post author

definition you mentioned. that we knows. give some example and calculation. its calculation not theory. don"t waist time for giving simple definition.

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