Stiffness Definition and 144 Threads

http://www.flickr.com/photos/53948823@N08/6193375731/ I need to solve this problem but with member 2 as L+e instead of L, and omit the load.. Since I only see one degree of freedom, i don't know how to set up the matrix to solve for the 3 forces. I have K11 = EA/L + (EA/(L+e))cos2(30) +...

Hi all, I am trying to understand the concept of equivalent stiffness of a beam. As I see it, the equivalent stiffness is the stiffness of a linear spring that would deflect the same amount under the same load. For a cantilever beam with a load P and a deflection \delta at the free end, if we...

Hi guys, I must simulate with simulink an air spring, connected to a device. In many book is present this non linear formula: k(h)=-(n*P0*Ae*h0^n)/(h^(n+1)) Where: P0 is the air pressure at the equilibrium condition h0 is the spring heigth at the equilibrion condition Ae=F/P0 is the...

Hello can someone please tell me the difference between stiffness and hardness and between strength and toughness? thanks

Hello guys How can I calculate the following stiffness of the springs/suspensions in the case of inclined suspension (angle between suspension and axle)? I know that the lateral separation of the springs causes them to develop a roll resisting moment proporcional to the difference roll...

hi.. This is abdul I am carrying a impact of sphere on a composite laminated plate. i wanted to calculate the contact force when sphere impacts the plate.. or can anyone help me how to get the stiffness of plate.. or deflections in plate.. with respect to time Thanking you Your help will...

Homework Statement A 0.5m high and 100mm diameter post is to be made from concrete reinforced by 10mm diameter steel rods. How many steel rods should be used if the axial stiffness of the post is to be at least 2000kN/mm? Homework Equations n = number of steel rods D = diamater of the post d...

ok i loaded a composite laminate beam across the centre of a 1.44meter span with 415N load. This deflected the beam to a distance of 0.05m (5cm). Im having trouble calculating the stiffness from this. The composite laminate is 5mm of wood in a glass fiber sandwich with both the top and bottom...

So, I am trying to assemble the Stiffness Matrix in my Finite Element Analysis course (Structures) and I keep coming out with a stiffness matrix that is not symmetric. I learned that for any neutrally stable structure, the stiffness matrix must be symmetric. Are there special cases that I am...

hi i need to calculate the torsional stiffness of a sample, the data is in the excel file. To work it out it = 1/samplek= 1/totalk - 1/machinek the machine k was given as 42800NM/radian the total k is the slope of the line which comes to y=658x what i don't get is what am i meant to...

Hello. Supose that we have a cantilever beam. For a small force P applied at the free side of the beam, we can find an expression for the maximum deflection: \delta=\frac{P l^3}{3 E I} If we want to use this beam as a string, we can find its equivalent stiffnes noting that P=K_{eq} \delta, so...

What does the spring constant mean for the overall "stiffness" of a spring? Does a larger spring constant mean the spring would be more difficult to compress or stretch? I know that Hooke's law states that F=-kx, and that the units of k are in N/m, I just want to know what the spring constant means.

what is the spring stiffness?!??! In outer space a rock of mass 4 kg is attached to a long spring and swung at constant speed in a circle of radius 6 m. The spring exerts a force of constant magnitude 720 N. What is the speed of the rock? i found the speed it is 32.8 m/s part 2: The...

What is the Spring Stiffness? [b]1. One mole of iron (6.02x10^23 atoms) has a mass of 56 grams, and its density is 7.87 grams per cubic centimeter. You have a long thin bar of iron, 2.4 m long, with a square cross section, 0.15 cm on a side. You hang the rod vertically and attach a 234 kg mass...

Hi all, I'm trying to design an arch for a project (will be about 4" long). This arch will be experiencing a load on its vertex, and I need to make sure that the arch will not deform very much. What is a good way to model the stiffness of an arch like this? As far as I know, there is no...

How is stiffness affected by potential?

Homework Statement Can somebody please explain me: What does it mean that Longitudinal Stiffness (EA) is equal to infinity? What does it change if for some members of a structure "EA = infinity", and for other members "EA = finite number". Homework Equations I know that we use longitudinal...

Inter-atomic force in a Hydrogen molecule -- finding "spring" stiffness Homework Statement At about 2000 K the heat capacity (at constant volume =) increases to (7/2)k per molecule due to contributions from vibrational energy states. Use these observations to estimate the stiffness of the...

Homework Statement One mole of iron (6 *10^23 atoms) has a mass of 56 grams, and its density is 7.87 grams per cubic centimeter, so the center-to-center distance between atoms is 2.28 *10-10 m. You have a long thin bar of iron, 2.9 m long, with a square cross section, 0.05 cm on a side...

Homework Statement A spring has a relaxed length of 6 cm and a stiffness of 150 N/m. How much work must you do to change its length from 8 cm to 12 cm? Homework Equations 1/2Ks,f - 1/2Ks,i The Attempt at a Solution 1/2 Ks,f^2 - 1/2 Ks,i ^2 1/2 (150)(0.06m)^2 -...

I am having trouble forming the Global Stiffness Matrix for a planar truss. Does anyone know of any good online resources to help me with this? I've found a few, but haven't been much help.

1. A container of mass 100kg runs on overhead rails. the container is mounted on two wheels each having a mass of 15 kg,a diameter of 1.2 m and a radius of gyration of 0.4 m. A)the total kinetic energy of the vehicle when traveling at 4ms-1 B) the spring stiffness reguired to bring the vehicle...

Homework Statement One mole of iron has a mass of 56 grams and density of 7.87 g/cm^3. You have a long thin bar of iron, 2.0 m long, with a square cross section, 0.12 cm on a side. You hang the rod vertically and attach a 151 kg mass to the bottom, and you observe that the bar becomes 1.03 cm...

Homework Statement Your niece is working on a unique science fair project - a clock built around a small mass vibrating on a little spring. Her prototype version is working ok, but it's running too slow. Given your experience in this course, you suggest to her that a stiffer spring should...

Homework Statement node1 node2 O---------------------------------------O a rod with 2 nodes: x1=axial force at node1 x2=axial force at node2 u1,axial deflection at node1 u2,axial deflection at node2 l=elements length E=young's modulus...

Hello... I have a 6x6 stiffness matrix. I also have a 3x3 matrix containing the direction cosines of the x',y', and z' reference system. My question is: How can I transform my 6x6 stiffness matrix or how can I get a 6x6 transformation matrix?

I know that stiffness is load per unit deflection. I have the load versus deflection curve for a steel plate. Is it possible for me to find the stiffness of the plate? Thank you.

Homework Statement A 65 kg trampoline artist jumps vertically upward from the top of a platform with a speed of 5.0 m/s. (Ignore small changes in gravitational potential energy.) a) How fast is he going as he lands on the trampoline, 3.0 m below? ANS: 9.2m/s NOTE: I understand how to get...

Hi, I am trying to write a MATLAB script to do an elastic analysis of 3D frame sturctures. The method I am using is the direct stiffness method, but I cannot find the equations for the 12x12 stiffness matrix for each member in the global system. If anyone has any information on 3D matrix...

Hi all: I am fresh to engineering and have basic question. I have a 100 inch length and 40 inch wide & 6 in depth plate , it has honeycomb structure what I mean 0.125 inch face sheet of aluminum on either side and rest (6-.125*2)is honeycomb made of alumnium.It is supportted on 4...

Homework Statement Problem is (to be solved in software, this is actually a programming assignment): -\triangle u = f on \Omega = (0,1)^2 u = 0 on \delta\Omega And f = 2x(1-x)+2y(1-y) And the exact solution known to be u(x,y) = x(1-x)y(1-y) Okay, so the actual assignment is about...

Hi all, I am doing a research project on how vertical tractional forces (applied at the tail of rats) affect scoliosis. I know the lateral deviations for each weight at specific columns of the spinal cord...however, I want to assess the lateral force at each specific point due to the vertical...

I spent almost 2 days to solve the following stiffness matrix \left(\begin{array}{c}f1\\f2\\f3\\f4\\f5\end{arr ay}\right)=\left(\begin{array}{ccccc}20&-20&0&0&0\\-20&40&-20&0&0\\0&-20&40&-20&0\\0&0&-20&40&-20\\0&0&0&-20&20\end{array}\right)\left(\begin{array}{c}0\\d2\\d3\\d4\\0\end{arr...

how can we increase or decrease the stiffness of a spring

I get the urge to crack my neck once everyday to relieve the stiffness. The urge is even stronger after I put in some good hours of reading or computer related activities. And man does it feel good! But I fear that there may be some medical implications to this. Like maybe tearing something...

Iv done an experiment with a spring wher you add mass and record the new length. From a table of these rusults iv plotted length (m) against mass (kg), like so Now i have to calculate the stiffness, k, from this graph with the equation: mg = k (l - lo) so just to varify that what iv...

Homework Statement A mass m hangs from a spring with stiffness constant k. The spring is cut in half and the same mass hung from it. WIll the new arrangement have a higher or a lower stiffness constant than the original spring? Homework Equations F= -kx The Attempt at a Solution...

Would I be correct in saying "Material stiffness - the ability of a material to resist bending when subject to compressive AND tensile forces"... especially the last bit. Thanks in advance.

Why would a rope have a lower bending and compressive stiffness that a rod of the same diameter, but would have the same axial tensile stiffness?

I require a detailed understanding of the stiffness matrix in the analysis of rods,beams et In the beginning of stiffness matrix derivation the textbooks say force at ith degree of freedom(dof) to hold unit displacement at jth dof when all other dofs are zero. let us analyse this...

I want to derive the theory of finite element using my own understanding. With this derivation i want to understand the fea theory of rod element I call the nodes as "points" in a structure. This scenario is for a simple one dimensional displacement of points(that is the single degree of...

many references tell that the dynamic stiffness will reduce when vibration amplitude increases. And the experimental result is just so. But why there is such rule?who can explain it theoretically?

i have put this question in other forum also. I have understood the stiffness matrix generation for a single rectangular element as below. I consider each node having 2 translational dofs each in x and y coord system. There are 4 nodes in this rectangular plate element and hence 8 dofs...

i know that the stiffness for a line element is calculated as fl/ae where a is known as area and l is the length,f is the force applied and e is the youngs modulus. How the stiffness of a plate element are calculated?