Stiffness Definition and 144 Threads

I've crossed the threshold into 60 now, and my warranty has expired. I'm OK muscle-wise and stuff - where I'm not OK is in the stiffness of my joints. My shoulders in particular are stiffer than they ought to be, but my neck and hips are too. I do not have arthritis, and I do not have pain...

Hi there, I was wondering if someone might know why I am getting incorrect signs for my structure that I am working on using the Direct Stiffness Method? I am following the procedure that I was taught when I was at University and I can't completely remember everything. I am designing a...

4 I am working on problem c and I'm not sure if I'm doing it right, please can you help me understand if I am on the right lines? I want to get a better understanding of lagrange method problems Here is my working: I have labelled ##k_1,k_2,k_3,k_4, k_5## left to right Generalised...

Hello, I have a problem with reducing a stiffness of a front suspension. Unfortunately I don't understand how to get the reduced stiffness on the right side in the picture. (k_f=k/cos^2E) Thanks in advance for your help. Many greetings, Semat10

I have been experimenting with a minimal "toy" physics engine for JavaScript, called verlet.js but now I want to switch to a more versatile and feature rich engine. One feature I would like to use is the ability to assign a reference angle to a pair of segments (i.e. links, i.e. distance...

Summary: How to express ωₙ in terms of only mass (m) and stiffness (k)? I tried doing it with F=kx but it is out of my ability to simplify it to only m and k. Here is my approach:

As is well known, the stiffness of an FEA model decreases with a refined mesh. What's the rigorous derivation of this?

i am new to MATLAB and and as shown below I have a second order differential equation M*u''+K*u=F(t) where M is the mass matrix and K is the stifness matrix and u is the displacement. and i have to write a code for MATLAB using ODE45 to get a solution for u. there was not so much information on...

does this Beam, composed of three elements and 4 nodes(considering lateral deflections and slopes) has an 8x8 global stifness matrix and if so is the global matrix calculated the same way as a 6x6 stifness matrix for the same kind of beam but only with two elements and 3 nodes

Inflatable SUP boards, LEI kites, Inflatable kayaks, and so on get their stiffness by having two layers of airtight materials separated by pressurized air. And it gets stiffer the higher pressure you can contain, or by increasing the separation between the materials. The simplest way to look at...

Hi. I'm a physician trying to understand the micromechanics of lung injury due to overdistension. The basic idea is that overstretching of the plasma membrane of the lung epithelial cell causes "stress failure" --> i.e. plasma membrane rupture --> cell death. The concepts of stress, strain, and...

I'm 3d-printing a part that is 110mm x 40mm (XY-plane). I have to keep it light weight, so I made it thin - 0.6mm (Z direction) and filled the surface with holes to remove as much weight as possible. Then I added a grid of 2,5 mm high "walls" in the XY directions to make it stiffer and a couple...

I read in some articles that the force in optical tweezers can be written as: F=kx, with no minus because the force will increase as the distance increased and the particle moves to the source..., This I can understand, but what I can not understand if I make integral (it is conservative force)...

Hi folks, I have an interesting problem here from the real world, it's a design i am working on. So I have an object that is pressed by an hydraulic press with 50kN, let's call it F_before. Then I drive in a jig to fixate it. But the part that holds the jig has a limited stiffness. Hence if I...

My query here is, Suppose there is a 2 kg mass To oscillate it/vibrate it, it will take some force and it will have some natural frequency Now I increase the mass to 5 kg so to vibrate it, won't it take more force and so at the end, won't the natural frequency of the object increase? as its more...

Summary:: I would appreciate it someone could help me as my mind is completely gone on this and I am struggling to get the correct answer. Hello, I am trying to use this formula to fill in the rest of the table and I expect to get an answer between 0-5 x10-11. However i am getting nowhere...

Hi, In the question outlined in the images (apologies for the poor quality of the scans), the chosen solution has opted to use a symmetry argument and proceed from there. Question is from "Structures: theory and analysis" by Williams & Todd My question is: How could we approach the same...

Here's a picture of what I tried. I was wondering if this is correct?

I have a spring which I am using to cushion a simple device, but it has proven to be too stiff for the purpose. Is there a way to reduce the stiffness of a spring, without making it brittle or malleable? I have access to ovens which can achieve 550°C, which can also quench in water or poly-oil...

Hi, Is there a simple formula to calculate the lateral stiffness of a compression spring when both ends stay in parallel (see figure)?

For an anisotropic material, is there any way to analytically determine the elements of the stiffness matrix? For orthotropic and isotropic materials, there are analytical expressions relating the stiffness matrix elements to the elastic modulus and poisson's ratio, but I do not believe this...

Good day All, while trying to solve this exercice I was puzzeld by the solution approach indeed, they use the symmetry of the structure, they have made a cut on the hinge where the force F is applied (the force F has been divided by 2 for the symmetry reason), and ONLY replace it with a...

Homework Statement I am given c11, c12, and c44. What is poissons ratio ν and the E modulus E [100] for a single crystal for uniaxial strain in [100] (if Fe is isotropic)? ii) What is the anisotropy factor A? (iii) There is: sigma=[100 0 0; 0 100 0; 0 0 0]Mpa What is the transverse strain in...

I've been thinking about rolling motion, helped by @kuruman's excellent Insights article on the topic. A crucial insight from that article is that, when a wheel rolls along a flat surface, its axis of rotation is through the instantaneous point of contact with the ground, not through its axle...

Just want clarification on two equations. So basically, I want to calculate the time period T of the complete oscillation of a cantilever. I use this equation. Is E equal to young's modulus or is it equal to stiffness? If it is equal to stiffness, can I use this equation to calculate the...

Hello everybody, I am currently working on desinging a tool, and I would like to get your advice on how to increase it's stiffness. The tool will be used for correct positioning of a component. It consists of 2 parts : And

I am currently taking a physics class and I'm studying for the final and I've been stuck on this problem and haven't been able to find help from the book nor help from online. The professor said the answer was .56m, but I've been trying formulas for about an hour now and haven't been getting...

Which of the two is stiffer in bending? 1. A circular rod of diameter D and length L. 2. A circular rod of diameter d and length L, surrounded by a tube of inner diameter d, outer diameter D, and length L. The tube is not bonded and can freely move. It seems like an easy solution in that we...

Homework Statement In this question , I don't understand why the KBC is 4EI / L ...Homework EquationsThe Attempt at a Solution I was told that for the far end pinned or roller supported , the K = 3EI / L , so shouldn't the KBC = 3EI / L.. Is the author wrong ? In the 3rd photo , we can see...

Hi I was given the following problem in my coursework: Homework Statement "A spring is initially compressed by 50mm when a steel ball of mass 2kg is released from just being in contact with the uncompressed spring. Determine the spring stiffness (k) of the spring." Homework Equations F = mg...

Is it possible that due to the less stretchness of th inner muscles of lower leg, the upper muscles waste? Being a student of physics, I don't know their names.

Let's say you have part of frame contacting the ground, such as the feet on the base of the tripod. Assuming each leg is equally spaced around a center post, how would you go about analyzing this type of structure? I'm trying to teach myself how to use the stiffness method, but all the examples...

Hi all, In the attached photo, you can find a plate supported along the edge by "frictionless" support and I am trying to obtain the stiffness matrix using the node at the center. I wonder why the Kxx and Kyy (highlighted) are not equivalent or even near to each other, any suggestions?

Hi, I know that Ansys APDL can determine the stiffness matrix for any structure, I would like to know if I can determine the overall stiffness for this structure or not if yes how can I do this? thanks.

not a problem from anything just a question i have. problem: I know that youngs modulus (E) is known as stiffness. but when solving for elongation you can write e=FL/AE as F=se where s=AE/L and s is also known as stiffness. so I'm confused why is s and E known as stiffness when E is in the...

What is the difference between stiffness and Young Modulus and how can you calculate the stiffness?

Dude i have a problem to find the equivalent stiffness (k') and damping (c') of this equation ? thank youvery much physics forum

I'm aware of the concept of rubber as an entropic spring and how increasing the temperature increases the modulus/stiffness of the rubber. I've seen the experiment of how heating a strip of rubber supporting a load will cause it to shorten. But also a rubber will transition from its glass-like...

Stuck on a question in my Construction Materials coursework. Not asking for anyone to solve it for me but would be grateful if someone could point me in the right direction: As far as i was aware, stiffness = force/deflection, data which is not obtainable in a hypothetical circumstance.

Homework Statement Hi, can I please get some help with deriving the analytical formula for bending stiffness of a cantilevered tapered tube. Homework EquationsThe Attempt at a Solution

Is it possible to create a cantilever beam with constant or increasing stiffness. I've been experimenting with several different shapes and profiles, and have not had any luck. I know that there are shapes with constant stress throughout, but I'm hoping to find a shape with constant or...

1:question A weight W is suspended from a rigid support by a hard spring with stiffness constant k . The spring is enclosed in a hard plastic sleeve, which prevents horizontal motion, but allows vertical oscillations. A simple pendulum of length l with a bob of mass m (mg<<W) is suspended from...

The problem is attached.

OK. First of all, I'm novice at Physics so this question may be weird. Above, there are 2 expressions for strain-stress relations. Let's assume that all components in the matrix are variables, not zero, not E, nor not G in the first picture. The first one is written in 2D matrix form, whereas...

Hi everyone, I'm french, so sorry for my bad english. I have a problem to compute the damping as a function of frequency. In fact, I plot the transfer function between the input (which is a force applied bu a hammer) and the output (which is an acceleration). Therefore, I can analyse the mode...

Homework Statement Hi, I need some help analysing this frame. First of all i bellive its hard, if not impossible, to get as detailed results by hand calculations as my softwear CSI Sap2000. Becourse of shear and axial deformation. Is it possible to obtain the stiffness matrix of this frame at...

Hi, There is a rattling noise in one of the automobile passenger car gearboxes that we designed. After few experiments and observations, it was found that the noise is because of incorrect clutch stiffness and hysteresis behavior. I have got some fundamental questions about both: 1. Clutch...

How to derive the formula to find the bending stiffness of an isotropic tapered tube which is cantilevered with a point load applied at the free end?

Homework Statement 1. A structure with weight of 100 kN and which has a natural period of 1 second. Compute the stiffness of the structure. The structure has 5% critical damping. The structure when at rest is subjected to a half sine wave loading having a magnitude of 10kN and lasting 2...