What is Normal stress: Definition and 43 Discussions
In continuum mechanics, stress is a physical quantity that expresses the internal forces that neighbouring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material. For example, when a solid vertical bar is supporting an overhead weight, each particle in the bar pushes on the particles immediately below it. When a liquid is in a closed container under pressure, each particle gets pushed against by all the surrounding particles. The container walls and the pressureinducing surface (such as a piston) push against them in (Newtonian) reaction. These macroscopic forces are actually the net result of a very large number of intermolecular forces and collisions between the particles in those molecules. Stress is frequently represented by a lowercase Greek letter sigma (σ).
Strain inside a material may arise by various mechanisms, such as stress as applied by external forces to the bulk material (like gravity) or to its surface (like contact forces, external pressure, or friction). Any strain (deformation) of a solid material generates an internal elastic stress, analogous to the reaction force of a spring, that tends to restore the material to its original nondeformed state. In liquids and gases, only deformations that change the volume generate persistent elastic stress. However, if the deformation changes gradually with time, even in fluids there will usually be some viscous stress, opposing that change. Elastic and viscous stresses are usually combined under the name mechanical stress.
Significant stress may exist even when deformation is negligible or nonexistent (a common assumption when modeling the flow of water). Stress may exist in the absence of external forces; such builtin stress is important, for example, in prestressed concrete and tempered glass. Stress may also be imposed on a material without the application of net forces, for example by changes in temperature or chemical composition, or by external electromagnetic fields (as in piezoelectric and magnetostrictive materials).
The relation between mechanical stress, deformation, and the rate of change of deformation can be quite complicated, although a linear approximation may be adequate in practice if the quantities are sufficiently small. Stress that exceeds certain strength limits of the material will result in permanent deformation (such as plastic flow, fracture, cavitation) or even change its crystal structure and chemical composition.
In some branches of engineering, the term stress is occasionally used in a looser sense as a synonym of "internal force". For example, in the analysis of trusses, it may refer to the total traction or compression force acting on a beam, rather than the force divided by the area of its crosssection.
First, I am trying to find the external reactions in A and B, but I have only one equation relating ##V_A## and ##V_B##, what other relation could I use ?
Once I find the reactions, I can find the external moment as well. Then, I may draw the diagram of moments in each cross section and then...
This is the structure
I already made the calculation of all the bars T = tension and C = compression, these are the results.
now I am asked to calculate the normal stress in all the bars but I don't understand where to start, could you tell me how? here is the diagram of the first node but I...
Now here is the part where I'm sort of stumped myself:
Could someone let me know if my reasoning is valid? The professor explained it during office hours and all I got out of that was that something cancels out and the answer is 0.
Let's say you have a material element with normal and shear stress. These stresses were computed using stress transformation. When the material deforms, should the normal stress vectors remain normal to the surface (sketch 1) or parallel to the other surface (sketch 2)? Which would be more...
What's really the difference between pressure and normal stress? Also I know pressure acts normal to a surface from the outside
Do normal stress acts from inside?
I'm reading bird transport phenomena and this is confusing
Homework Statement
Here's a snapshot of the problem:
Homework Equations
+ Newton's 2nd Law.
The Attempt at a Solution
My question is: why does the delta P term have only a single 40 kN force considered, whereas for delta EF there's an F/2?
Thanks for your time.
I am trying to determine a normal stress balance at an axisymmetric and dynamic fluidfluid interface, ##z(r,t)##. For a static, free surface, this simplifies to the YoungLaplace equation: $$ \Delta p=\rho gz\sigma2H=\rho gz\frac{\sigma}{r}\frac{\partial}{\partial r}\left(r\frac{\partial...
Hello,
i would like to ask You a question about difference in results between EulerBernoulli method of analysis of stress in short slender beam and 3D FEA method mentioned in ansys aim tutorial here: https://confluence.cornell.edu/pages/viewpage.action?pageId=33636829
The problem looks like...
Homework Statement
"In a component under multiaxial state of stress, the ratio of shear stress to normal stress along principle places is _____.
A) 0.0 B) 0.5 C) 1.0 D) 1.5 E)2.0"
Homework Equations
σx' = (σx+σy)/2 + ((σxσy)/2)*cos(2θ) + τxy*sin(2θ)
σy' = (σx+σy)/2  ((σxσy)/2)*cos(2θ)...
Homework Statement
For the state of stress shown in the figure, normal stress acting on the plane of maximum shear stress is?
Homework Equations
Normal stress σn = σcos2θ
3. The Attempt at a Solution
Plane of maximum shear stress is 45o relative to the max stress of 100MPa.
So the total...
In the derivation of Navier Stokes equation there is a term for normal stress acting on the fluid element. While the cause of normal stress is the static pressure which is already present in the equation doesn't this mean that the same force on the fluid element is repeated twice with different...
Homework Statement
The stress distribution along the section of a bar is shown below. From this distribution, find the approximate axial force P in kip.
Homework Equations
δavg=P/A
A= (.6+.6)(.5)
δavg=30ksi[/B]The Attempt at a Solution
P=(30ksi)(.6in2)=18kip
It says this answer is wrong...
Homework Statement
Homework Equations
Equation of Equilibrium (Horizontal and Vertical Forces, Moments)
Normal Stress = F/A
The Attempt at a Solution
I have already solved the solution for this problem. For part (a), I simply found the force in the link, and used the cross area where the...
Homework Statement
For σBC end , i don't understand how the author get (20mm)(40mm25mm) = 300x10^6 (m^2) ...
Homework EquationsThe Attempt at a Solution
IMO, , the area should be the circled part (thin rectangular part of the rod) , but i only know one dimension only , which is 40mm , i don't...
Homework Statement
http://ocw.nthu.edu.tw/ocw/upload/8/256/Chapter_798.pdf refer to page 3
in the 2nd, 3rd pictures, i have problem of finding σx'Homework EquationsThe Attempt at a Solution
why can't use the formula to find σs ?
it's given that σx' = ( σx+ σy)(0.5) + (0.5)( σx σy)cos2θ +...
Homework Statement
why the angle of shear stress ( θs) is given by θp  45 ??
Homework EquationsThe Attempt at a Solution
the difference in angle of shear stress and normal stress is90 degree , am i right? why it's negative 45 degree? is it wrong?
Homework Statement
why the shear stress is maximum at the center ? while the normal stress is maximum at the boundary ?
Homework EquationsThe Attempt at a Solution
why shouldn't the shear stresss maximum at the boundary ? this is because shear stress is to pull the 2 surface apart [/B]
Hello,
Does anybody know how to compute shear and normal stresses which take place due to applied load?
My case is a simply supported beam (120x120x6.5 length: 4.2m) reinforced by a plate (20x120 length: 2m). Plate is welded on a top of a beam and external force (F=15 kN) is applied to the...
Hey everybody,
I went through a discussion with a colleague today about Finite element modeling of composite structures and how to interpret the stress analysis.
I understand that for isotropic materials, principal stresses could be used against the allowable stresses to see if failure will...
Hello
So I've done some calculations, I'd like to see if my stuff is right. Thanks :)
Please view attached http://i.imgur.com/AfMZyr0.jpg
area = (pi)(9^2) = 254.46
Cos53.13=15/CG
CG=25kN
Normal stress = 25000/254.46
=98.25
Hi, everyone.
I am learning fluid mechanics. One book says that for a infinitesimal fluid cell, surface force includes
1) the pressure, which is imposed by the outside fluids surrounding the concerned fluid cell
2) the shear and normal stress, which result in shear deformation and volume...
Homework Statement
Stuck on two similar problems:
"State the normal stress boundary condition at an interface
x_3h(x_1,x_2,t)=0between an invisicid incompressible fluid and a vacuum. You may assume that the interface has a constant tension."
The second question in the same but the fluid is...
Given the stress tensor in a point, determine the zero normal stress plane.
...2 3 0
T= 3 2 0
...0 0 5

Eigenvalues: σ1=σ2=5, σ3=1
It must be simple, but I don't know how to determine the normal vector of that plane analytically.
I know σ=0.
t=Tn=σ+τ=τ
If normal stress...
Homework Statement
In a prismatic bar (same cross sectional area throughout the entire length), the load applied to both ends is 100 N causing the member to be in tension. If the cross sectional area of the member is
5 cm2. What is the normal stress in the in kPa?
Homework Equations...
Homework Statement
In the steel structure shown, a 6‐mm‐diameter pin is used at C and 10‐mm‐diameter pins are
used at B and D. The ultimate shearing stress is 150 MPa at all connections, and the ultimate normal stress is 400 MPa in link BD. Knowing that a factor of safety of 3.0 is desired...
Homework Statement
Here is the problem along with the solution:
I am confused about part (a). Why is it that the area used is 2*0.008*(0.0360.016). If you draw a cross section at just one of the holes, wouldn't that give you the max average stress? So the area used should instead be...
Hi guys.
Please look at the uploaded picture.
Normal stress is difined as: σ= P/A. And the Maximum normal stress σ = P/ (b*h/cos(θ)) ??
The right answers should be σAB= 97,7 MPa and σBC = 66,5 MPa. But how do I calculate it?
What I have tried:
Force AB: 40* sin(60deg) = 34,641 kN...
Homework Statement
Everything needed is written in the question ( Open the attached image )
Nyhow the required is to find the value of P.Homework Equations
Shear stress = \frac{ \Delta V }{\Delta A} eq 1
normal stress = \frac{ \Delta N }{\Delta A} eq 2The Attempt at a SolutionFor the...
Homework Statement
A 12cm X 12 cm square plate of AISI 1010 steel (E=200 GPa) us subjected to normal tensile forces of 15 kN and 20 kN on the top and right edges as shown in figure P22. The thickness of the plate is 5mm, and the left and bottom edges of the plate are fixed. Find the normal...
Homework Statement
Here is the question with the solution:
The Attempt at a Solution
I understand the first part where they find the forces by summation of moments. However I don't understand how they got that area. Why would they take the diameter (0.016) and subtract it from the length...
Homework Statement
The 2000 mm long composite bar shown in Fig. 1 consists of an aluminum bar having
a modulus of elasticity EAl = 70 GPa and length LAl = 500 mm, which is securely fastened
to a steel bar having modulus of elasticity ESt = 210 GPa and length LSt = 1500 mm. After
the force P...
Homework Statement
Homework Equations
σ=P/A
σ=My/I
τ=VQ/ItThe Attempt at a Solution
I'm on part C, pretty sure I have A and B, so I'm using a W18x46 Beam. I have drawn shear and moment diagrams. I just want to be clear on what part C is asking...
I'm assuming this point is at the end of...
Homework Statement
Homework Equations
\sigma_x = \frac{M(x)y}{I}
I = \frac{bh^3}{3}
The Attempt at a Solution
For point A, I did the following:
I = \frac{t(2h)^3}{3}
I = \frac{8th^3}{3}
\sigma_x = \frac{3\tau_0}{4th}
\tau_{yx} = \tau_0
\sigma_y = 0
Are my...
Normal stress problem,.. Help me :(
link BD CONSIST OF SINGLE BAR 30MM WIDE AND 12MM THICK. KNOWING THAT EACH PIN HAS 10MM DIAMETER. DET MAX VALUE OF AVE. NORMAL STRESS IN LINK BD IF A.) ANGLE = 0 DEGREES, B.) ANGLE = 90 DEGREES..
http://i356.photobucket.com/albums/oo7/hids0902/fcdsafdsa.jpg
Homework Statement
What is the maximum normal stress in the beam and where is it located? The beam is 1m long, 0.2m high, and 0.05m thick (out of the page). The Modulus of Elasticity is 100Gp. The force is applied at an angle of 20 degrees with horizontal.

____________
...
length: 20mm
thickness = 0.5mm
delta t = 100 celsius
thickness of adhesive = 50 mm
and a picture of a Silion on top of a Copper
Questions: How to calculate the distribution of shearing and normal stress?
Any helps and ideas will be appreciated.
Homework Statement
is there any normal stress on torsional member?
Homework Equations
The Attempt at a Solution
My professor showed me a circular rod made up of rubber and she made a rectangular hole on the side of it and asked whether there is any normal stress on the torsional...
Homework Statement
Conceptual question  When considering beam connected to something say a wall by a cylindar shaped pin, why is it when the beam is in tension near the pin the stress is high as the load is applied over a smaller cross section (normal cross section  profile of the pin) but...
Homework Statement
An offset link supports a load of 30 kN as shown in figure 6. Determine its required width w if the total (combined) normal stress is not to exceed 73 MPa?
The cross section of the link is rectangular and has thickness of 40 mmHomework Equations
stress= N/A
I have tried...
Diagram: http://i177.photobucket.com/albums/w222/77whtrocco/NORMALSTRESS.jpg
Given: members AB, CD, and EF have xsectional area of 25 mm^2. E = 200 GPa. Neglect deformation in member GH.
Find: Normal Stresses in members AB, CD, and EF.
I know that I need to determine the axial forces in these...
ok...my engineering professor just gave us this crazy homework problem. he wants use to design a tool to measure the normal stress in a biological tissue. now it doesn't have to be extremely detailed in any way, but...we don't even know how normal stress is measured. the problem asks for it...
Two solid cylinderical rods AB & BC are welded together at B & loaded as shown. Knowing that d(1)=30mm & d(2)=50mm, find the average normal stress in the midsection of (a)rod AB, (b) rod BC.
B____________C
125kN> 
A______________...