# Questions tagged [strength]

This is to be used for topics regarding the strength of materials, the analysis of internal forces in a body and all the governing principles which considers deformation of bodies.

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### What is the Hoop stress and bending moment relation

So I am working on a club telescope project. I have to design the tube for the telescope. So I found hoop stress to be most critical stress. The tube's bottommost end has a mirror and a mirror cell. I ...
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### How to calculate the material and thickness I need for a certain force on it?

I am trying to figure out how to design how thick a material has to be so that the bar shown in picture 1 stays intact when a user is running on it. Background: The project is a treadmill and the user ...
20 views

### Techniques to make residential buildings more blast resistant

There are generally two approaches: First: use stronger materials (e.g. thicker RCC with fibres, go underground, etc). Second: for any given material, use a superior design. The First approach is ...
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### Conflicting steel strength Vs temperature graphs, NIST NCSTAR vs Engineering Toolbox

This graph is from NIST NCSTAR 1-6C And this graph is from the Engineering Toolbox. As you can see, neither the NIST yield or tensile curves match with the ET structural steel curve. Why? And which ...
24 views

### What is the shear force at point B? Is it +P or -P or zero? I am not able to find any source that gives the right information

I am not able to understand here that what should be the value of Shear force at point B. It seems to be a discontinous point, as there is point load there, but can we say about the exact value of ...
155 views

### How much weight can aluminum square tube support?

I'm building a bed platform in a campervan and trying to determine what type of aluminum tube to buy. I'm thinking to purchase 6061-T6511 aluminum Square Tube with 1.5" width, 1.5" height ...
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### Twisting of thick ring due to internal pressure

I have an axisymmetrical part that is subject to an internal (non-constant along the inner border, but constant in time) pressure (among other loads, but this is the one I am interested about) and I ...
29 views

### Fabricating a Strong Hub Shell for a Bicycle

I'd asked this question over at SE Bicycles but they think this is more an engineering question. The flange on my hub broke and I'm having to get one fabricated. The part is actually a cage that ...
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### Fabricating a Strong Hub Shell for a Bicycle

I'd asked this question over at SE Bicycles but they think this is more an engineering question. The flange on my hub broke and I'm having to get one fabricated. The part is actually a cage that ...
• 101
19 views

### Determine moment and shear stress door

Determine shear stress and moment of bolt: Internal Height of Door = 198.2 cm Internal Width of Door = 89.9 cm Thickness Door = 3.9 cm Weight Door = 45.76 kg or448.9 N Elasticity = 9.8 GPa or N/mm2 ...
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### Is it possible to model the connection of pre-cast and site cast concrete beam on FEA software such as Ansys?

I'm looking for a way to compare the joint strength of beam-to-column connections of pre-cast and site cast concrete. Is it possible to do this on a FEA software?
23 views

### 2" o/d aluminum pipe (1/4" wall) used as 10' 'axle' to 'roll' dock out of water

I'm curious how much weight this 'axle' could support? The dock wheels on ends are capable of 700 lbs each. The dock itself is 10’ wide. The axle will be placed under two 4’ x 2’ rigid black nylon ...
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### What are the change in forces with a ribbon under tension is twisted?

Consider pallet strapping. It has width W. When the strap is flat, it has some maximum breaking strength B. Now, let's put one twist in it over X feet. Mentally we have a VERY skinny isoceles ...
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### Failing engine A-Mount (bad design by the automotive manufacturer?)

I currently own a Tata Nexon Petrol car (in India) where I have seen (on facebook, Telegram, WhatsApp owner groups and youtube) that the A-Mount on the engine has suffered multiple failures for some ...
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### Relationship between how fast a metal cylinder can spin on its axis without breaking or deforming?

For simplicity sake consider a solid metallic cylinder which is $2r$ in height with a radius of $r$. For a given metal and $r$, how to calculate how fast can this spin in terms of rpm for a very long ...
150 views

### Optimal shape for cantilever beam subject to body weight only

How can I find the optimal shape of a cantilever beam subject only to its own weight, and having the following restrictions? The cross section is a rectangle Only the height of the rectangle can vary ...
55 views

### Superposition of cylinder stress and normal stress

I need to calculate the principal stresses for the given cylinder with thick walls inside filled with gas shown on this picture: I used the Lamé equations, namely: \sigma_{x} = p\cdot\frac{r_{1}^2}{...
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### Predicting breaking force of beam per length based on one testing

I've made a plywood carbon sheet and tested its breaking force, for a 200mm long, 50mm wide, 16mm thick it was 100kg +- I was wondering if it's enough to help me predict what will be the breaking ...
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### Angle of twist at D where 2 shaft connected through gears

So my frind and I find the answer for part A different also chegg says something else. But I can't see whats wrong with my answer. Dont expect you to solve it just show me whats wrong with my answer. ...
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### How can a material be good at damping, yet also be strong?

Good Damping Carbon bicycle frames have the unusual property that they are superior to aluminum frames in high-frequency absorption. A cyclist on a carbon-frame bike will feel tarmac chatter far less ...
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### Why are the water tank walls made of stretch film warping a lot whereas theoretically they shouldn't that much?

I am building a water tank of custom dimensions (1.5 m x 0.72 m x 0.86 m) out of stretch film. The stretch film is wrapped around a steel frame (see here for more info on this open source project). I ...
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### Why the size of top and bottom rollers is different in three point bend test?

In a short beam shear testing of polymers, the configuration is such that the top (loading) roller is bigger than the bottom (support) rollers. Why is this the case, and what happens when the size of ...
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60 views

### What does cycle mean in fatigue strength diagram?

A shaft at an usual factory might rotate 2000-3000 (10^3-10^4) per day. So, its rotation cycle easily reaches numbers indicated on X axis below. What does number of cycles in the diagram below exactly ...
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### Is the a similar method of calculating moment in inelastic bending like in the case of torque for inelastic torsion?

When calculating for Torque in torsion or for Moment in the case of bending, the concept is usually first introduced with the simplification of the assumption that the stresses and strains are in the ...
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### How do I calculate the strength to weight ratio of a material

I want to manufacture something using metal 3d printing. And I'm now choosing the material. Stainless steel is stronger but much heavier than aluminum, so I want to calculate which material can ...
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### Spherical metal ball contains high pressure superheated steam. If we allow it to cool in atmospheric air, at what pressure steel ball will implode?

Theoretically, I know that steam will start cooling slowly at constant volume to attain thermal equilibrium as per zeroth law of thermodynamics. After some time, steam will condense to water creating ...
90 views

### Resultant Forces in a vertical rod

This is a pretty basic question. So in the below figure is the representation of prismatic column. The forces are represented as P1 and P2. let x be an arbitrary cross section between A and B. The ...
1 vote
27 views

### Could electromagnets ever compete with the power of an antimatter annihilation engine? [closed]

So to make this easier to read, I've been using a few terms I'll explain really quick "MPP": (maximum physical potential) "MASS": (maximum atomic structure strength) According to ...
1 vote
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### Why are these food stretch films (LLDPE) holding one one-thousandth of the weight in reality than what is expected from the datasheet values?

I am trying to reproduce analytically the results found in this experiment where a weight of 3 x 5 lbs (6,8 kgs total) breaks the cling wrap (LLDPE) which is stretched over a medium size cooking pot. ...
82 views

### Strain As A Function of Deflection of a Hollow Cylinder

I should think that there would be a direct correlation of strain to deflection of a hollow thin-walled cylinder, but I've seen nothing as of yet. I must be missing something. For example, let's say I ...
102 views

### How to analyze strongest (honeycomb?) structure?

To be specific I have a structure consisting of a solid material (eg PLA) consisting of a top horizontal slab (eg 3 cm x 3 cm x 0.5 cm) and a bottom horizontal slab (translated vertically, of the same ...
134 views

### Torsional rigidity of a composite shaft in parallel

Consider the following composite shaft which consists of 3 different materials with modulus of rigidity of $G_1$, $G_2$ and $G_3$. Shaft 1 has length 2L, and shafts 2 and 3, L. Assume they are all '...
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### Timber strength in tangential and radial directions

Normally for structural timber, two values for compressive and tension strength are given. One value is given for timber in direction of the grain, and other is given at 90 degrees (perpendicular) to ...
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### The hanging of lead weights in the Cavendish experiment of 1798

I'm working to build the Cavendish experiment of 1798 according to Cavendish's own specifications. I have a question about the hanging of the 150 kg lead weights. As seen in the image, there is a ...
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### What are the physics behind a TV wall mount?

As I was installing this wall mount, I began to wonder how exactly physics is at work with it. In other words, how does the design of the mount play a role in ensuring that the mount itself supports ...
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### Stress in a L-shaped Beam due to Thermal Expansion

A L-shaped frame $ABC$ (right angle at $B$) consisting of beams $AB$ and $BC$ are fixed at ends $A$ and $C$ to rigid walls. Find the tensile stress at $A$ when the temperature of the frame is raised ...
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1 vote
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### Screw Calculations/Math

At the risk of every woodworker in the world snickering at me, I'm curious how strong my wood joints are and want to know how much weight a table supports. I'm an aero engineer who ended up in EE, but ...
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326 views

### Stress-strain Curve Interpretation

A significant barrier to my understanding of typical engineering stress vs. engineering strain curves is that for certain values of stress, there are multiple values of strain (i.e., the stress-strain ...
1 vote
993 views

### Failure load of hollow tube under transverse compression

How would one analytically calculate the maximum force a tube under transverse compression can withstand? I am specifically looking for a general equation to model the yield strength of a hollow tube ...
1 vote
583 views

### Design procedure used in beam design

In the design of beams, the principal stresses and absolute maximum shear stresses are not calculated. Instead, we calculate maximum bending stress using flexure formula and equate it to allowable ...
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### Waterlogged multistorey apartment

I fraction invested in a real estate project several years back. Mid way through the construction, after about 12 floors, the building contractor filed for bankruptcy. An asset reconstruction company ...
2k views

### Brittle = highly stiff but not very strong

I was trying to imagine materials undergoing collisions, and thought about materials that do not deform at all. Naturally this is an idealization that does not exist in reality but, if it did, I ...
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### Why von-mises criteria considers the second invariant of deviatoric stress? [closed]

Why only the second invariant is considered? What about the third invariant?
353 views

### When we replace supports distributed reaction by point reaction in thin beams, is that considered an application of Saint-Venant principle?

I read about Saint-Venant principle which is about the effect of replacing forces by equivalent forces system that effect on the same small region of a rigid body, all examples I come across are on ...