Failure Definition and 248 Threads

Hello All, I know there are rules of thumb and thread engagement calculators online but I am trying to find mathematically what the minimum number of threads acceptable would be. I currently have an eyebolt that will be torqued to a specific value. This eyebolt setup will then need to lift a...

I was wondering if someone can explain how failure criteria work when dealing with viscoelastic materials. I'm quite new to this, so I only know how they work with brittle and ductile materials. (not in too much detail either). And now that I'm at it anyway, if possible an explanation on...

I'm curious about this failure mode. I had a cheap ($3.82) wall clock from 2017. On Tuesday, it stopped working, getting stuck at the 41 seconds position. The second hand twitches every 1 second, but it does not advance. Since it was so cheap, I threw it away and bought a new one (also...

What are some creative ways to display fatigue failure of material due to axial, bending, torsional loading using common household items? This is an experiment I have to do at home, I need help with some ideas

Got a vacuum to create bubbles in water, they advertised it as "boiling water" but it didn't seem like boiling in my book. If there were bubbles in water I am guessing there was a vacuum of 20% (20% atmosphere.) I am just estimating the 20% number. In any case, there didn't seem to be any...

just want check if i got this right. is there anything i can improve or add on this example i have? Cause and why. A cause could be bending or twisting of the prop shaft due to high torque. High torque causes high angle of twist and torsion. The high torque cause high shear stress...

I was thinking this past morning of the challenger explosion due to the stiff and cold failed O-rings in the fuel segments. I was trying to think of satellite failures, I couldn't find too much... Do you all know of satellite (components, instruments, etc) failures that occurred while in...

I need advice how to calculate thread pull out in aluminium 6063-T6. 12 bolts screwed into an aluminium plate (thread depth 25 mm) must withstand a load of 350 kg. Thanks in advance

https://www.flightglobal.com/safety/united-777-suffers-engine-failure-over-denver/142519.article https://www.flightglobal.com/safety/united-777s-failed-pw4000-appears-uncontained-forward-cowling-missing/142520.article...

https://www.nbcnews.com/science/environment/one-texas-storm-exposed-energy-grid-unprepared-climate-change-rcna289 The link above is an opinion piece that discusses the possible lessons from the experience in Texas. FYI: This was a textbook system wide grid failure, caused by off the charts...

Trying to troubleshoot a field failure on a purely resistive load on a 30A rated relay utilizing only a 24A load (cycled off/on for 45 min, 1x/day). Our wiring/load has been verified but this failure has been occurring sporadically but impact has been large. My question is, could a tin-plated...

Given we only have one number I assume we are to use Poisson distribution. Probability for a plane with two engines to fail require both engines to fail: $$P_2 = P_o(2) =p^2/{2!} * e^{-p}$$ Probability of a four engine plane to fail requires 3 or 4 engines to fail: $$P_4 = P_o(3) + P_o(4) =...

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...

Hi, I have this question: If random variable T is uniformly distributed over [a, b] , what is its failure rate? Please help

My guess is that the deformation immediately before would be the sum of elastic and plastic deformation, and the deformation after would be just the plastic deformation, and it therefore would decrease. Is this correct?

The dam is a series of massive re-bar and concrete wide base tapering to narrower top. Does anyone know if these structures are " tied" togeather via connecting rebar sections? I researched and apparently no piles were drive into bedrock so only the shear weight is anchoring the massive...

How did you find PF?: Google search How we can differentiate failure and fracture using Stress Strain Curve [Mentor Note -- thread moved from the New Member Introduction forum]

I had thought it would be failure of structural stability since in structural stability qualitative behavior of the trajectories is unaffected by small perturbations, and here, even tiny deviations using ##h## values resulted in huge effects. However, apparently that's not the case, and I'm not...

The situation is that we have 4.5 inch diameter pipe with a 300,000 lbf yield rating installed in a horizontal completion. The pipe is cemented in place but it is very likely that the one side of the pipe may not have any cement in it. During the fracturing operation, a sleeve is opened and...

The SpaceX Starship Mk1 prototype has been damaged beyond repair 20 November 2019 during a cryogenic pressure test. Entire top been torn off. https://www.space.com/spacex-starship-prototype-anomaly-pressure-test.html

Hi, I have a device I'm suspending from a chain and the chain attaches to the body with a pin. I'm curious how you would calculate how much weight a pin like that could take before failing. There is a block on the body and a bar on the end of the chain that slots into the block and the pin goes...

In a book it says that "we know of quantum phenomena in the electromagnetic field that represents a failure of superposition,seen from the viewpoint of the classical theory." I want to about what quantum phenomena is he talking about? This was from the page 11 of the book Electricity And...

Hi, I was reading about CMOS BIOS which was once used in computers to store BIOS settings is a CMOS RAM using a battery backup. This article, https://www.makeuseof.com/tag/why-does-my-motherboard-have-a-battery/, says, "If the battery fails on an older computer that stores its BIOS settings...

I have a little heating pad 12" X 15" runs on AC 120 volt has around 220 ohms resistance on low final got to hot burned up wire. What to replace it with using junk box parts light bulb wastes 10% for light would need metal cage to keep bulb from breaking seems like not good way. Have 300...

Homework Statement how do we establish failure of uniqueness on this first order differential equation ## y(x)= x y'+(y')^2##Homework EquationsThe Attempt at a Solution [/B] general solutions are ## y= cx^2+c^2## where c = constant and ## y= -0.25x^2## ## -0.25x^2+cx+4c^2=0## ##x= -2c ⇒...

[I've searched the site and did google. I couldn't find a satisfactory answer] I have the motor characteristics and the moment of inertia of the object I'm supposed to spin with it. I have to design the shaft considering the torsional failure. Now, if I consider the inertia of the body, there is...

Been tracking down the most unusual bug I've seen in 40 years of programming (mostly in assemlber and C). It manifests in the test suite for an object oriented XBase language implementation that's been ported everywhere from Palm Pilot to OS/2 to the Blackberry tablet to Windows to, now, Qnx7...

A Soyuz flight that was supposed to launch two astronauts to the ISS had a booster failure (half an hour before this post). The Soyuz capsule separated from the rocket and landed, the crew is fine. Rescue teams got to them quickly. While they had to endure higher g-forces than usual they seem to...

Why theories of failure have been developed from 1-D tensile testing. Why can't we go 2-D testing or 3-D testing?

Hi, I'm currently working on a project for which I have to determine the Life-Time of a certain mechanical component within a certain confidence interval. By sampling a small number (let's say n = 10) of these components and measuring the number of hours until failure, I want to determine this...

Homework Statement See attached photo Homework Equations Stress = F/A Area = pi d^3 / 4 Sum F h = 0, Sum F v = 0, Sum M = 0 The Attempt at a Solution Hey everyone, after reading the question a number of times and not knowing for certain where to start, I figured because the stress and area...

Homework Statement The problem asks to find out whether the rod yields at points in section A according to the tresca and von mises criteria P is 120N Homework Equations Shear stress= VQ/It Stress= Mx/I shear stress= Tp/J The Attempt at a Solution I picked 2 points at section A. The...

Hi all. I recently was accepted to Purdue Northwest and I'm planning to take something related to stem once I get everything in order; however recently I failed my real estate exam. This was very discouraging for me, and although I'm over it for the most part, I still can't help but wonder how...

After reviewing some old threads (e.g. here), anecdotally I see that fuel rods do suffer failures on occasion, but it appears not very often, as is intended. My question is, why not more frequently? Given a power reactor neutron flux of 1014 n/cm2-s, it seems like every atom in the cladding...

What is the situation for my hard drive now? Can I fix it with a software? Should I change it? The PC is working with no problem? What should I do now? Should I change the hard drive in the service? S.M.A.R.T status is bad. There was nothing a few days ago. I cannot understand how this has...

I am working on finding a solution for a gear box field failure. Failure description: In the deep groove ball bearing only one rolling element has a pre-mature fatigue failure (Image-6.jpg) and rest of the all ball is in good condition (image-05.jpg). Do anyone has seen the same kind of...

One of the encouraging points of string theory is the ability to single out specific gauge groups, a feat that Chew himself thougth impossible back in 1970. But it extracts groups as SO(32) or E8xE8... elegant it is, but not simple. So let's ask, is there really no way single out SU(3) from...

Homework Statement I get ##~t_1-t_2=\frac{u}{c^2}(x_1-x_2)## Homework Equations Lorentz transformations: $$x'=\frac{x-ut}{\sqrt{1-u^2/c^2}}$$ $$t'=\frac{t-ux/c^2}{\sqrt{1-u^2/c^2}}$$ The Attempt at a Solution t' are times in the moving system S' and are equal, the times t in the fixed...

Hi everyone. I'm a college student, and I need help of experts with gears. What I know is that there are two dynamics in gear : rolling and sliding. And I heard that the main cause of failure (wear) of spur gear is rolling. Then... how about the cause of failure in the case of helical gear...

I have a problem which is a beam with 2 machines on the beam and one of them has an operating frequency between 200 and 600 rad/s that transmits a force to the beam. I have to determine the number of cycles to failure of the beam. It's stated in the problem statement to account for the mean...

I wasn't sure into which category I should post this, so feel free to move it into a more appropriate place. As part of my work I'm solving a system of nonlinear equations, of a usual form: $$\vec{F}(\vec{X})=\begin{pmatrix}F_1(X_1, X_2, \cdots X_N) \\ F_2(\cdots) \\ \vdots \\...

(Sorry for the terrible title. If anybody have a better idea, post and I will edit. Also I have no idea of the level so now I just put undergraduate since the problem is fairly easy to state.) Suppose I buy ## N## sensors which the manufacturer tells me will fail at some point and the failure...

Hello all, I am a 19 year old female currently in my first semester of engineering school. I have taken other classes such as Physics I and Calculus I & II and done pretty well in them. Today I got my statics exam score back and received a 60%...the average was a 72%. A 60% puts me at the very...

I am working on a project for a cube-sat to go up on a balloon to 40 km. My team has been talking to some other groups who have worked on other cube-sats who say that our resistive heaters need to be Kapton heaters rather than 1D heaters like what we have designed for. They claim that our...

I am doing surface failure analysis for a ball bearing SKF 6025, , as an exercise, It has been used in the washing machine tub, after some time a noise has been reported and it is no longer rotating. When i got it I opened the seal and captured the attached photo. I had a feeling that it suffers...

[Big forewarning that this is a bit of a rant written by a sleep-deprived person at the edge of their wits, but I am genuinely asking for advice as well, if a bit desperately.] [tl;dr: I flunked out of one of the best undergrad physics programs in the US in my junior year due to health issues...

Hey, working on something for a personal project and was wondering if you could point me in the right direction. I have a 47 inch hollow steel tube that I'm going to cut the end 6 inches into a half circle tube . I have a load of 200 lb at the top and am wondering how about I would quickly...

I currently need to show that the attached locking pin assembly will not shear or deform under load (total load is 53.5kn, shared over four of these pins) Could anyone advise on how to model this as a beam? Cantilever? What calculations can I use to prove the pins will not shear or deform to a...

I have simplified the problem down to something like a physics textbook question, although this is a practical problem where the pivot on my rotary actuator has been damaged by a faulty driver which caused the armature to ram into the endstop. Obviously this needs better protection. My problem...

which has higher failure rate: linear algebra or intro to programming. I understand failure rate might be skewed: math majors, who are gifted and interested in math, are required to take linear algebra but not intro to programming, while CS majors are required to take both. Which class do CS...