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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25 views

Why von-mises criteria considers the second invariant of deviatoric stress? [closed]

Why only the second invariant is considered? What about the third invariant?
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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 ...
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What is the physical reasoning behind metal becoming stronger and harder if heat treated?

I was wondering that if a proper process of heat treatment (heating to a temperature above upper critical temperature, then soaking and then quenching) is applied to a metal like steel, then what ...
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Finding out the direction of the maximum shear stress in a 3d stress tensor

I came across a problem where I was asked to find out the direction of the maximum principal stress in a given stress tensor , with the help of eigen vectors I was able to construct an equation which ...
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2answers
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Help with understanding bending moment diagram of a frame structure

I have an exercise where I should calculate and draw a bending moment diagram for a frame structure. The frame structure is similar to the one below, image taken from http://structx.com: I would like ...
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4answers
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Mechanics: example of less mass/volume gives more strength

Lets assume we have a mechanical element from uniform material that is supposed to work in a static load conditions. Moreover lets assume there is no gravity or gravity is negligible. Are there any ...
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How do I calculate the strength of a carbon fiber tube?

I am not a mech engineer and have been struggling with this for a while, I feel like it is pretty straight forward but I'm missing something. The problem is a horizontal tube that is supported at one ...
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61 views

Server rack modifications - strong enough?

Question: Can I modify this rack and have the result still strong enough to hold the content? I have a server rack made from Steel. However it is 1980's old and doesn't quite conform to modern ...
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Calculating break point (bend) of a material

I'm trying to compare a really tough polyurethane to baltic birch plywood to see if I can use it instead (a lot of subtractive processes to the plywood, want to eliminate it) So what i'm looking for ...
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How is the assumption that stress and strain are elastic everywhere is valid for STRESS-LIFE method for fatigue life calculation?

Stress life method is generally employed for high-cycle fatigue (HCF) applications. while HCF region is approximated by $\sigma=a(N)^b$ which gives a linear graph on log-log scale, for steels it ...
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Applying forces from the inside of a bar

I was reading Schaum's Outline: Strength of Materials (fifth edition) when I came across this solved example problem from the Tension and Compression chapter: The solution was clear to me, however ...
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1answer
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Calculating the diameter of screws that are on radius 160mm from axis of rotation. I need help - I don't know If I'm thinking in the right way

First of all, english is not my first language so if there are some mistakes I made - I'm sorry and I hope everything is understandable. The example I am trying to solve reads the following: The gear ...
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Manual vs Fusion360 calculation of natural frequency of beam

I'm trying to uncover the natural frequency of a mass-less beam with 2 masses attached but getting different answers from Fusion360 vs a hand calculation. L1=1m, L2=2m, m1=10kg, m2=20kg, Young's=...
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Increasing torsional-stress resistance of an Auger at its motor-shaft joint

An auger is used to move plastic balls and is rotated by a stepper motor. Due to the balls getting jammed sometimes, this induces stress on the auger at the motor-shaft junction and breaks. Images ...
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3answers
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Equivalent sheet metal thickness of different alloys

I want to replace steel plates that are being used as trim tabs on a boat with 90-10 cupronickel. The main design parameter is to make sure the plate has no less flex than the part being replaced. In ...
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Filler Material

If I was to add a filler to a metallic substance, is it possible for the Young's modulus to decrease as filler content increases? Also, when a filler is added, how do the atoms change for improving ...
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How many support beams/rods needed for a firewood storage cabinet

I am building a firewood storage cabinet which should support around 100-150 kg of firewood. The cabinet is made out of wooden boards (...
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Is it possible to use Plain Cement Concrete post for fencing?

I am in need of around 700-800 posts to fence my farm in a semi-arid area in TN state, India. In my place granite posts mined from quarries are normally used. It costs around Rs 300-400 per post(6-7ft)...
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Good estimates for torque generated while turning a dial

I'm trying to design a little device which is hand-driven and which involves turning a bevel gear pair. I want a small gear pair but I don't want it to be weak. The forces involved will be small (it's ...
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Which will be stronger for securing a cantilever umbrella in a deck

I am securing a cantilever umbrella baseplate to a deck. The decking timber will be reinforced with a pine nog between the deck joists. The options that I have are to use 10mm stainless steel coach ...
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Can strength be expressed in a single value? Can flexibility?

I'm trying to communicate information about the strength and flexibility of certain materials to laymen. Are there any recognised proxies for strength and flexibility? I've tried: $$\text{Strength ...
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Best support for a granite table top?: Flat bar 316L Stainless Steel or equal box section or unequal box section

Project is outdoor granite topped table. Table legs are two isosceles trapezoids crossed together at 90 degrees, with the legs having an internal angle of 80 degrees, made from 100 x 100 x 4mm 316L ...
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Stopping force exerted on a rope. (Checking if rated strength is sufficient)

I have a 23 kg dog, and a rope lead that is rated to 50 kg. If the dog is running away at say 6 mph and I pull on the lead to decelerate and stop the dog within say half a second or say 0.5 meter what ...
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Is there a mode of failure criterion for a valid unconfined uniaxial compressive strength test for intact rock core specimens?

I have read the latest revision of the ASTM D7012 standard, which includes the test procedure for determining the unconfined uniaxial compressive strength of intact rock core specimens. There, I do ...
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How to calculate specimen strain in split hopkinson pressure bar?

I want to plot the stress-strain chart for a specimen after a test. In the output file of excel, I have "Strain of transmitted bar" and "Strain of the incident bar" I also have ...
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Securing aluminum angle to steel tubing without through-bolts

Overview I'm planning a rack for solar panels on the roof of a cargo trailer. I will mount the panels to a pair of 15 series 80/20 aluminum extrusion rails. I will mount the rails to the roof of the ...
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How do I calculate the strength to weight ratio of this object?

I have an object that weighs approximately 10 grams = 0.022 pounds. I know it can hold at least 45.1 pounds without breaking. It's a cube-like object so I placed many books on top of it and weighed ...
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103 views

How to measure the stiffness of a rectangular beam, and compare it to a triangular beam?

I'm an amateur at engineering, working more on musical instruments, and I'm often in confusion regarding what exactly constitutes stiffness of a beam for a load applied on it so it could resist ...
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57 views

Same E for axial and rotational stiffness?

When we solve frames, we assume that the materials are infinitely rigid in axial direction, so all deformations are due to bending. So this means, we assume infinitely rigid modulus of elasticity, E, ...
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30 views

Strong resin for fibreglass

Is there a binding material that could be reinforced with woven glass fibres cloth for tensile strength, but which offers reasonable containment against high pressure when used minimally? Ie ...
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What is the white fiber in the copper wire of headphones?

I got a pair of in-ear headphones, broke the left earphone, bought another set, broke the right earphone, and joined the leftovers of both. I found white, grey, or beige fibers near the copper of the ...
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Poisson relationship between area and length of electric wire

I was given the following formula to relate the change of area against the change of length of an electric wire with a Poisson ratio: $ {\Delta A \over A} = -2 \nu {\Delta L \over L} $ where $ \Delta ...
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What is strain/loading rate dependence/sensitivity of compressive strength of brittle materials?

What is the definition of strain/loading rate dependence/sensitivity of compressive strength of brittle materials? Is it general strain/loading or it is specific for the brittle materials?
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How to estimate the tensile strength of inch diameter steel round?

The tensile strength for 1045 TGP Precision Steel Round is said to be 91 ksi. Although, different diameters must be a factor, right? Would a 1" diameter rod be 104.5 ksi or 1045 ksi? Say I want ...
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Should I use ST or LT values for extruded rod?

In MMPDS for AA7075-73511 (extruded rod) the Table 3.7.10.0(g3) show both ST and LT values for transverse directions. For a rod with circular cross section there is really no Short and Long transverse ...
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Beam buckling criterion?

If I have an I beam which I subject to some bending load, how can I calculate when the thinner middle part of the I beam will buckle? I though I could use Euler's critical load formula here, but it's ...
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3answers
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Beginners material science for handling a load

I’ve got a reasonably strong grasp of Newtonian mechanics, but as far as material science goes I don’t know which of the many material properties I need to use to solve my problem: I’m trying to mount ...
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Where does Second moment of area come from?

Where does the second moment of area come from and how to derive it from scratch, or what is the basic intuition behind it? In other words, what are the origins of $$I_{xx} = \int\int yy \text{ }dxdy$$...
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1answer
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Strength of bolts

I was wondering if it'd be a good idea to attach a 10kg load to the end of a movable steel rod by fastening it with just one M5 bolt. Looking at Misumi's datasheet, M5 (Class 10.9) has an allowable ...
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Is inverse hall-petch relation valid crystals larger than nanocrystalline?

The image shown here is of ceramics, where they varied the grain size and measured the strength. For example, let's take Al2O3. There we observed that strength first increased from 3 μm to 95 μm. But ...
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RHS beam deflection with support on one end

A 1400 mm long galv steel beam, size 40x20x2. 80 mm of the beam on one end is welded in flat position to a platform. How much weight can I put safely on the other end? What if instead of being flat ...
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1answer
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Stability of 3D-printed mask after sterilisation

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6797553/ https://www.hatchbox3d.com/collections/pla We are 3D printing masks that need to be used by medical staff treating COVID19 patients. The first ...
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Is there any way to improve the strength of simple at-home aluminum/copper/brass castings (sand-casting hammers)

I'm just getting-into melting-down cans to make aluminum-based slingshots, hammers and the like. In my ignorance I didn't realize that copper/brass were also things that I could process which has ...
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Column Buckling Boundary Conditions -- Welded Tubing Practical Application?

I'm trying to do some calculations for a personal project. I'm trying to understand column strength / buckling. My questions relate to Effective Length Constant, which is based on Boundary ...
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4answers
106 views

Which post would be stronger?

Just a quick question for you. Well hopefully. A contractor has installed a retaining wall with colorbond fence on top. In the contract he stipulated that he would use 65mm x 65mm x 1.6mm powder ...
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1answer
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Mounting outdoors camera using aluminum 5052

I designed a simple U shape 2mm sheet metal bent mount for a 4kg outdoors CCTV camera. The mount was accidentally produced from 5052-H32 Aluminum instead of 6061-T6. Is it common to use 5052 ...
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What is the actual stress in a certain point in a body?

I'm reading my book on strength of materials and it says that the stress in a point depends on the orientation of the section that we are observing, and since there are infinite number of section that ...
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Calculating shaft diameter

I'm designing a circular shaft that's going to carry a spread radial load of about 200kg and also transmit a 160Nm torque. I'm not very familiar with materials but what I'm guessing I'll be able to ...
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Analysis Of Planar Frame Using Hardy Cross Method (Moment Distribution) With Sway

The image shown below is a sketch of the structure/frame that I am attempting to analyse using the Hardy Cross (Moment Distribution) Method. I need to find the bending moments, axial forces and shear ...
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Is there a relationship between depth/diameter/etc... of meteoric craters and the strength (eg:compressive strength) of the target material (sand...)?

So I am trying to write a high school research paper (3700 words) on the topic above. I am not sure if there is such a relationship, but I think intuitively we can agree that different materials will ...