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I will expand on DKNguyen answer, because to my knowledge also the two reasons are: reduce contact/bearing stresses (having a significant effect on thin finishes live galvanisation) change the joint tightening characteristics (see joint diagram). reduce contact stresses on surfaces. The basic idea is that since contact stress is defined as: $$\sigma = \... 27 It is for spreading out the stress. But it is also for giving the bolt a bearing surface to turn on. The washer always goes on the side (nut or bolt) that is being turned. It prevents it from marring up the work surface and also changes the tightening characteristics. I don't know the specifics of that though but that's what I was told by a toolmaker. Always ... 16 Except for special applications, most washers are made of dead soft steel, which deforms under the compressive load imposed by a tightened bolt head. As the washer smooshes, it minimizes stress concentrations caused by bumps under the bolt head and surface flaws in the part the bolt is running through. 15 To visualize part of Nmech's answer: in the image, the washer actually greatly increases the contact area of the bolt head. The bolt head looks pretty big: But most of that is the shaft, which obviously does not spread out load on the material. So the actual contact area looks like this: Comparatively, the bolt head on the washer looks like this: That's a ... 7 I think you might have a misconception regarding to how far the pressure from the fasteners extends. One subject you might want to have a look into is "bolt joint stiffness". The most popular is the "Rotscher’s pressure-cone method". Essentially there is a pressure cone which radiates outwards with an pressure cone angle a. According to ... 6 The Load-Displacement (or Load Extension) and stress strain diagrams are two diagrams identical in shape. See below. The main visible difference is the values on axis (which are at first glance neglected). So, it is natural when you first encounter them to question why do you want to learn about a stress and strain diagram which has obscure quantities (as ... 6 Another important part of the answer is the symmetry of the stress pattern. The stress caused by a bolt head varies greatly between the points of the bolt head and the straight sides. As a result local stresses, which are what you really care about because those are what the materials have to withstand, can be much higher than the average stress. A washer's ... 5 What is really proportional to the distance from the neutral axis (let's denote it z) is the strain. For pure bending and a symmetric cross-section the equation for strain is given by$$\epsilon(z) = \frac{z}{\rho}$$where: \rho or R is the radius of curvature of the beam Because in the linear region the constitutive equation is \sigma(z) = E\cdot \... 5 The direction of Forces isn't necessarily along the connecting element. If that happens depends a lot on the constraints between the different elements. For example see the following image: In the left column is a "welded" structure, while on the right column is a pin jointed structure (a basic truss) if you like. On the top there are the shapes ... 5 I just found an answear, the keyword is "stress concentration". Sometimes, the material is removed to make a stress relief in an element. Some examples: The origin source I found it: https://www.youtube.com/watch?v=QtSki5nfO2g 4 The simple most obvious answer is Weight. And that additional weight would offer little to overall stiffness. See this answer for an example of the marked effect that stiffeners may have on the behaviour of steel plates. 4 Well, "adds strength" relative to what? A single-piece continuous hull is the strongest & most reliable but you can't see through it. Adding a windshield to the windshield frame of a car makes the structure much stronger than the relatively thin rectangular frame itself. When weight is a concern, as with the beams and cross-braces on a bridge,... 4 If I understood correctly you are only after the stress-strain curves. Figure: Stress strain curves for different types of materials (source What's pipping) Perfectly Elastic : (referred to as Linear Elastic) returns to its original shape, and the force is proportional to the deformation (definition may vary) Perfectly plastic : (referred to in the image ... 4 It is actually more complicated than that. the magnitude of the stress increases 8 fold the tensile forces increase so that they generate the counteracting bending moment. When you decrease the cross-section from 1mm x 1mm to 0.5mm x 0.5m, the cross-sectional area decreases to 1/4 of the original but the second moment of area decreases by  \left(\frac{1}{... 4 According to this site, the pipe is made in accordance with euro standard EN10219 and conforming to EN10240. The minimum upper limit of yield is 235 MPa. EN10255 seems to be the British standard for tube steel. I suggest to get the relevant standard to verify the strength of your pipe. https://www.acciaitubi.com/product/construction-tubes https://www.... 4 Regarding the problem you have, without reviewing the results its difficult to make a definitive answer. However, if you are observing high loads near the weld, I think you should try to make geometric modifications, to decrease any stress concentrations or loads. The reason is that welds are generally very "temperamental". What I mean by that is ... 4 Yes, it increases and decreases strength in traditionally steels. Depends on what steel you have and what you mean by "thin rods", and the weld process , and the specific weld parameters. Properly selected filler metal will be close to the base metal strength. Common stick electrodes are "60" which means the weld deposit will be over 60,... 3 From what I see, in this picture from the Shigley book, if I really had to, I would extrapolate to 0.5 (or more precisely interpolate between the limit cases). The limit cases for very thick plate (d/h=0) and very thin plate (d/h\approx \infty) have values for d/w close to 0.7. (I would hazard a guess that these solutions are based on analytical ... 3 Here be dragons. Or, to paraphrase a hadith of the Prophet Mohammed, "There are seventy ways to compute element stresses, and all of them are wrong." The naive approach is to differentiate the element shape functions to find the strain at a point, and then use the stress-strain relationship for the material. The problem is that since the shape ... 3 There are at least two contributing factors to that: a) development of grains (the following is mainly an excerpt from this question ) and this Usually thinner steels exhibit higher yield points (see cold roll sheet catalog page.8) and ultimate tensile strengths (see Steel construction) because, sheets of steel, that come out of rolling processes (especially ... 3 Actually, the pressure inside the vessel is uniform and constant everywhere. What happens is that geometry results in reduced stresses in one direction and not in the other. There may be some confusion here with respect to stress and pressure being the same thing. Although they share a few similarities (\frac{F}{A} and units [Pa] or [psi], they have a ... 3 The loads asserted on the hull of a ship are shared between the hull plates and the internal ribs and bulkheads. Most of the flexural strength comes from the ribs and bulkheads. 3 Anelastic is a material that exhibits a delay in the deformation with respect to the loading. figure 1: Anelastic material bevahiour (left: wrt to time, right: stress vs. strain) (source Princeton) Visco-elastic are materials that the load to obtain the deformation also depends on the strain rate. I.e. How fast the deformation is applied. It might depend on ... 3 First of all, whenever I see stresses so localised near the boundary, I always think that there is something wrong. IMHO, the max stress at corner is an artifact, probably due to overconstraining the model. I.e. I expect you have fixed the entire face, and as a result there is an additional (non-real) component of the stress. There may be other factor ... 2 Since you are essentially using infinitesimal changes, then higher order differences can be neglected. I.e. following from your equation$${\Delta A \over A} = {{0.25\pi(d+\Delta d)^2 - 0.25\pi d^2} \over {0.25\pi d^2}} = {{2d \Delta d} \over d^2} + {{\Delta d^2} \over {d^2}} = -2 \nu { \Delta L \over L} + \big( \nu {\Delta L \over L} \big)^2  because $\... 2 In the old days we used the formula- Stress = PD/2t , and the hoop stress was twice the axial /longitudinal stress . Pressure vessel heads were usually half the thickness of the walls because of the lower stress relative to the walls. 2 Your best bet is to rig the planer with a couple of carpenter's horses or something on the sides. However, if we want to go your way need to check the following. Overturning moment on the fully extended setting with 44" cantilevered rollers. Torque on the joint between the two drawer slides. Let's say your machine and its base weigh 40# and the base ... 2 For hot rolled , the thicker section cools slower so has coarser pearlite and coarser grain size because the grains have more time to grow larger during the slow cool. A secondary factor is the thicker section is worked less / less strain to refine grains. The lower strength affect of the slower cooling thick sections also occurs during normalize and quench ... 2 There are a few factors affecting the strain rate behaviour of materials. The components of the stress-strain curve that you will find that increase with increasing strain are: yield stress ultimate stress modulus of elasticity while : failure strain to fracture usually decreases with$\ln \dot{\varepsilon}\$. A very important factor that affects the stress ...