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Questions tagged [structural-analysis]

Structural analysis is the determination of the effects of loads on physical structures and their components. Structures subject to this type of analysis include all that must withstand loads, such as buildings, bridges, vehicles, furniture, soil strata, prostheses and biological tissue.

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2D Solid - Axisimmetric - Missing properties and material

Goodmorning, I'm trying to understand how 2D solid elements work. I want to study the local buckling of a simple aluminium pipe with thin walls. From what I understood, I can use 2D solid elements ...
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47 views

Maximum tensile and compressive stress in a T-beam

Where does the T-beam come from? There's just a straight beam resting on two supports. And where do 10 and 80 come from? I am so confused.
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37 views

Determining the direction of internal forces in a truss

I am learning the method of joints, but there's no explanation on how to figure out the direction of internal forces in my course. How do you know that BA is tension and BC is compression?
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How to state the PSD value (random vibration)

In random vibration analysis, the load is given as a PSD (power spectral density). The values are often $G^2/Hz$, but I have an example where the PSD is a pressure $Pa^2/Hz$. The value is written as $(...
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FEA: What is the difference between a spider of RBE2s and multiple SPCs

I am not sure what the difference is between using a spider of RBE2s. and multiple SPCs across a face. I've heard that the spider is the more accurate method as multiple SPCs make the model overly ...
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43 views

How to find the diameter of bolts in a flanged joint?

So I'm given this question with the following diagram: Two sections of a pipe are joined in a flanged joint as shown in the Figure below. The difference in pressure from interior to exterior is 2 MPa....
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What equation are we using to describe forces in FEA?

Engineers often use Finite Element Analysis software to solve for stresses inside complicated structures to generate pictures like the one above. I am familiar with FEA as a method to solve ...
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What are the possible implications of the heating of the structural stonework of Notre-Dame cathedral during the fire?

Yesterday, Notre Dame cathedral caught fire. The roof and the central spire were destroyed and some of the stonework was subjected to high temperatures for an extended period. What are the likely ...
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How to compute core stress in honeycomb structure?

Assume I have a honecomb(sandwich) panel under distributed normal load. Each edge of this panel is simply supported(pinned) as on the picture below: The problem is how to find the core stresses σ-z (...
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Influence of a diagonal fold on a web + double fold situation

I need to build a steel frame with a steel web in it, as illustrated below. Flanges of the frame will be welded, as well as the web, along its whole perimeter. Would adding a diagonal fold to the web ...
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Determination of Warping Function for Thin-walled Multi-cellular Beams

I am trying to find warping function $\mathcal{T}$ for a thin-walled multi-cellular beam. There are four rectangular cells. The governing differential equation for $\mathcal{T}$ is Eq. 8.98 as shown ...
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Traction Force or Reaction Force

I am doing an FEA of a link plate of a chain drive system. the plate is subjected to traction force at one pin joint this particular link is in contact with the sprocket. it is also in contact with ...
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Why/how normal shear stress is zero in thin-walled beams?

Please explain how the normal shear stress (shear stress normal to the cuve, C, defining the cross-section of a thin-walled beam) is zero. I have attached a screenshot from a book which says that the ...
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Why not build container ships from plastic?

This may sound crazy but bear with me. I was thinking about why cargo ships are built from such heavy material as steel, while smaller boats are often made of plastics. I know cargo ships carry a lot ...
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Can I use fixed support for a frame?

Can we use fixed support at columns in a frame? Because If we do so , there will be 2 moments when we will cut the section.
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Need help with FEA bar analysis problem

I'm trying to solve this which is to find the total deformation of the bar. I'm trying to implement the finite element approach, but I am getting way too large of numbers. Here is what I did in ...
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Should the corbel angle always be estimated as 60 degrees in masonry construction, or is there a formula to use instead?

In educational construction material as well as engineering publications, the corbel angle for significant excess loads, and also for substantial openings, in an ordinary brick wall is usually ...
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Why do stress concentrations really occur?

From doing some research I've learned that internal stresses inside an object can "concentrate" on sharp edges, as shown in the above picture. For that reason we often make fillets so that the change ...
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Why would a SMD (spring mass damper) model of steel break down?

Under what conditions would steel be able to be modelled as a 3D SMD model, and under what conditions would the model break down?
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Rotational and translation DoFs in structural mechanics

I'm a computational person, and I don't quite understand how rotational DoFs are manifested in the linear elasticity equations. I understand the translational DoFs are simply the displacement ...
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1answer
31 views

Member weight in a planar truss?

So I'm given a question in which a Truck drives over a pratt truss bridge. In the question the truss is in 3D. I'm given: 1)The loads from each axle of the truck 2)The weight of each member in the ...
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1answer
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How to allow only one mode of resonance in a cantilever beam

So I am designing a MEMS structure consisting of cantilever arrays. For my problem, I want the cantilevers to vibrate only at their 1st mode of resonance and reject all the other modes of resonance ...
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45 views

Analytical calculation vs FEA

In terms of calculated stress, strain, displacement etc which method yields more conservative results. Analytical calculation or numeric calculation?
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Honeycomb structures vs shear stress

Honeycomb structures are made of top and bottom shells and honeycomb geometry at core. In terms of bending load, maximun normal strains take place on top and bottom hence, sheet parts can support them ...
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Drucker-Prager Model Parameters, a Proper Choice

My task is to write a code from scratch for 3D elastoplasticity, namely a DP model (see for example DeSouza Neto, et al., 2008, Chapter 8) having yield surface $$ f(\mathbf{\sigma},c) = \sqrt{J_2(\...
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Possible improved approaches to 6mx3m moment-resisting frame with eccentricity+torsion, in advance of detailed engineer discussion

I'm putting a steel frame in, to "open plan" the rear of a brick cavity-wall terrace house in the UK, which will then have a single storey extension added behind it. I have already retained a ...
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Displacement of Gaussian point after structure simulation

When we did the simulation, we would get deformation and got each nodes displacement. In physics, it shows the trajectory of a system of particles of the objects. Is it the same as the displacement ...
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47 views

defining the dimensions of a bucket elevator chain link

how to define the shape of a heavy duty chain link when the pitch of the chain and the traction load that the chain is subjected to is known? lets say i consider the traction load as the maximum load ...
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2answers
41 views

Material for car mounted fire extinguisher bracket

Don't try this at home. I am taking personal responsibility for what happens in my car. Hi all, I recently purchased a fire extinguisher for my car (it weighs 1.5 lbs or 0.68 kg). I browsed the ...
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1answer
39 views

Calculation of natural frequency in a hinged beam

What I tried: Using the conjugate beam method to find deflection and hence stiffness of the beam, but I am unable to find reactions in the conjugate beam.
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53 views

Impact capacity of tension cables, columns and foundations

A rock is falling from an embankment of mass $m_a$ at a height of $h$. Below, a fall protection fence catches the rock, dissipating the energy through tension cables to steel posts and then into ...
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1answer
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Supporting flexible square plate of uniform density in equilibrium with only 4 rolling contacts placed along the square's diagonals

Consider a flexible square of uniform density with vertices (0,0), (0,1), (1,0), (1,1). I need the 4 coordinates for rolling contacts along the diagonals that will stably support it. Someone could ...
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1answer
53 views

How is Load Transferred in a fully supported base

Suppose, you put a point load on a plate that is completely supported. The pressure under this plate is Force divided by the area of the plate. If I make this base very large, then pressure will be ...
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Analizing Vibrations Influence on Dynamic Weighing

I have a very sensitive scale used for dynamic weighing (by dynamic I mean that the scale and load cells are actually beneath a belt conveyor that actively weight product when it´s being transported ...
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compression buckling under lateral load

I'm trying to figure out what size of round tube to use for a tensegrity structure that'll probably have people climbing on it. The rigid elements are 21' steel tubes, and in normal cases they ...
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72 views

stress/shear analysis of components

I am working on analyzing a few problems, but have not really come across this type of stress concentration problem. Does anyone know where I can study the analysis of this situation? Pressing ball ...
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1answer
40 views

Stress Tensor decomposition into Compression & Tensile forces

I'm working on a project that does a finite element simulation of a mesh. I can output the stress tensor at each node, but I'm not so sure how to implement failure criteria. If my material is brittle,...
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2answers
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How to calculate stress in a cylindrical-uniaxial-loaded bar with sudden changes in its diameter

How can I calculate the von Mises stress in the cross-section of a bar like this that is axially loaded?
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STEEL CONNECTIONS

Hi, so, would you consider the connection detailed here as fixed or pinned during your structural analysis?
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Portal frame stability

Is there any way a portal frame with pin joints at the top of the columns can be stable? Are portal frames ever done with pin joints at the bases? (Aside from those with raft foundations/combined ...
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Analysis method for two-way slab floor with central column

What method would be appropriate to analyze this concrete structure? A two-way rectangular concrete slab with walls and central column. I would like to understand how to model it with either yield ...
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Most efficient way for finding the rotation angles after moment distribution (Cross method)?

First of all, I have taken a look at the Grinter's method, which is similar to Cross, but balancing angles instead of moments. My question assumes that we are using the Cross method, and not the ...
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1answer
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Normalizing the compressive stress to a cylinder

I'm not an engineer but a neuroscientist. I do research in spinal cord injury whereby a clip is used to clamp the spinal cord to induce a bilateral compression injury model. My research looks at the ...
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1answer
81 views

Stiffness as a function of thickness

Let’s say we have a thin band (made out of PLA, 3D printing material) with a rectangular cross section. In drawing, it would look something like this: Let’s say a force of 15 N is to be applied from ...
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1answer
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Percentage area of steel for a retaining wall - standard formula doesn't make sense to me?

I'm looking at the usual UK/EU standards formula for the reinforcing steel area percentage, in a retaining wall. Essentially in "usual" cases it comes down to 0.13% of the cross-sectional area of Tw (...
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1answer
152 views

Natural frequency of a column + mass

Consider a system made of a cylindrical column (fixed on the ground) with a mass attached on top of it (B). Both the mass of the column and the mass are not negligible. Depending on the value of the ...
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1answer
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Can secondary beams be supported to columns occaisionally?

If there are secondary beams running between primary beams, and columns support the primary beams, then is it allowable to have the occasional secondary beam pinned to a column? Otherwise it seems to ...
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What does 'Analysis Model Value' in NASTRAN optimization mean?

I am new to MSC NASTRAN and PATRAN. I am running a simulation on composite laminate optimization. While creating the design variables for the study, I noticed that there is a parameter called '...
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2answers
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What is the 'application standard' referred to in EN 1993-1-7

I'm using the Eurocodes for some structural analysis and am looking for the limiting value of deflection of a plate. EN 1993-1-7, Section 8.2 states: For limiting values of out of plane deflection w ...
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What diameter aluminum pole do I need to lift 100 lbs vertically?

I am wanting to use an aluminum pole (as a Jin Pole) to lift the mast on my sailboat into place. My mast is about 30 ft. long and weighs between 80 – 100 lbs. The aluminum pole would be stood ...