Questions tagged [mechanical-failure]

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113 views

Specifications of Tensile Test Specimen?

I am Currently Working on Measuring Various Mechanical Properties of Metalic Materials using Universal Testing Machine (UTM) at Various Temperatures. I know that for Testing at Ambient Conditions, ...
1 vote
2 answers
129 views

How to align a shaft with gear box and mechanical seal and uc bearing?

I have a 15 inch (381 mm) shaft with 24.95 mm diameter. That shaft is attached with a gearbox (ratio 5:1). The gearbox is driven by a motor (rpm 2750). There is one UC bearing and mechanical seal and ...
1 vote
1 answer
425 views

Design Factor and Design Uncertainty Calculation Question

I recently had a discussion about design factors and design uncertainty. Looking in Shigley's Mechanical Engineering Design, pg. 17, ed. 3, there is a detailed discussion of this topic. The authors ...
0 votes
3 answers
85 views

Need help analyzing torque transfer and slippage condition between parts

I have a scenario where Plate A (light blue) shown in the image below is being pressed against two different plates that are in contact with different sections of Plate A. I would like to know which ...
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0 answers
22 views

Impact on high frequency radial forces on ball bearings

Dear Stackexchange forum, Do high frequency radial forces (e.g. 6kHz) do significantly increase wear and reduce the life span of ball bearings? I am looking for an expert in ball bearing research ...
2 votes
2 answers
72 views

Determining elastic limit for a nonlinearly elastic material, to be used for calculating chord modulus (i.e. Young's modulus) in tensile testing

I have a protein material that is nonlinearly elastic; from the get-go, the stress-strain curve shows quite an immediate curvature. I have to use chord modulus (reference to ASTM E11-04). The problem! ...
0 votes
1 answer
31 views

Difference between failures

I'm studying about the phenomena that enlargement of the pipe entrance due to particle impingements. Our group calls this phenomena as erosion. But it seems to be fatigue failure in mechanical ...
0 votes
0 answers
27 views

How do you go about picking a belt in design?

So when you want to pick a beam to use or determining the thickness of a load bearing beam, or picking bearings, there is some calculations you do to see if its life expectancy or f.s or to see if the ...
0 votes
0 answers
24 views

Probability of kitchen toaster breaking

does anyone have any data on the probability of a kitchen toaster breaking such as mechanical or electrical faults? For a school project- teacher put me in charge to find this
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46 views

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 ...
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0 answers
34 views

Can the cooling fan in laptop or ceiling fan shaft fail as result of critical speed? But that's not often the case, even if they rotate at high speed

Cooling fan in PC start very fast. Is there any chance of it's failure due to resonance? In opposite, ceiling fan starts very slow, why doesn't it fail by resonance? Does regulator have any ...
0 votes
2 answers
52 views

Are there disadvantages to using a single multispan beam, vs separate simple beams, for materials that tolerate tension as well as compression?

Suppose the following beam situation within a mundane building (viewed from above). Assume vibration and torsion aren't issues. Suppose we have a choice to span a gap in 2 different ways: (Grey = ...
1 vote
3 answers
846 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 ...
4 votes
2 answers
277 views

Do yielded columns buckle?

A sufficiently slender column will fail under compression below yield stress by bowing, releasing it's axial elastic strain. This is called buckling. Depending on the slenderness of the column, the ...
3 votes
2 answers
108 views

What is the reason for forbidding liquids for cooling in drilling on cfrp/Al or cfrp/Ti stacks?

I recently did some research on the effect of cooling on CFRP/Al7075 drilling.But I read somewhere that liquids are forbidden for cooling operations on these multi layer plates !!! , And I wanted to ...
0 votes
2 answers
61 views

What is the best time interval in condition monitoring programs for checking rolling bearings?

The time intervals between observing or measuring the vibration of rolling bearings in industrial plants are so important in condition monitoring programs. For instance, some experts measure the ...
3 votes
3 answers
2k views

Is a gear usually held to a shaft by friction or an adhesive?

So, where I work, we have this arcade game, which is a classic claw machine. IN order to raise the claw up and down the machine makes use of a worm gear, like so: (although for the meticulously ...
6 votes
4 answers
446 views

Is radians a dimensionless quantity?

Quite often while calculating angular velocity we come across the quantity radians per second. How do I treat radian dimensionally?
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0 answers
28 views

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 ...
8 votes
4 answers
9k views

Would engineering bricks explode if used to build an oven?

I'm building a pizza oven and, to do so, I bought a whole load of engineering bricks (not these but similar). They've got five holes vertically through them, each hole is 2x6x6.5 cm (80 ml) and the ...
0 votes
2 answers
184 views

Why does stress act a point instead of on an entire area normal to the stress?

I've often heard stress acts at a point and not on an entire cross-sectional area to which the load is applied normally. Im a little confused here, Let us consider an area of cross-section ...
3 votes
2 answers
1k views

Why is the thin-walled cylinder more likely to experience failure along its axis than along its hoop/circumference?

I was watching a YouTube video to understand the concepts of hoop/circumferential stress and axial/longitudinal stress in thin-walled cylinders and their formula derivation. So the formula of the ...
0 votes
2 answers
952 views

Does a change in specimen dimension affect the measured yield strength and tensile strength?

I am having a hard time trying to understand the effect of geometry on a specimen's yield and tensile strength or if there even is one. If there is an effect or not, why is it so? Thanks in advanced!
1 vote
0 answers
58 views

Latch design for home exercise equipment [closed]

I have a latch design problem and need your help - many years in software engineering aren't helping me much here! Two pieces of 60x30mm RHS become parallel/adjacent (on the 60mm face), with a 5mm gap,...
-1 votes
1 answer
441 views

Length of semi major axis for the ellipse in "Total Strain Energy theory"

The equation describing the "Total Strain Energy Theory" (Haigh & Beltrami's Theory of failure) is given as follows: $$σ_1 + σ_2 - 2μ σ_1 σ_2 ≤ (Syt)^2$$ where $σ_1$ and $σ_2$ are ...
2 votes
2 answers
878 views

How to prevent screw from loosening?

This is a clevis made for linking the tie-rods to the steering rack. This part is under dynamic loading and is getting loosened. We tried using jam nuts but it did not work well. Due to loosening the ...
2 votes
3 answers
2k views

Buckling vs. Yielding Failure of Columns

As I have been working through examples of construction projects, I've noticed that in nearly every case of a structural column (sample size considers only homogeneous material columns, no composite ...
1 vote
1 answer
111 views

mechanical Strength of 3D printed part

If the material is manufactured by 3D printing (laser sintering) then what will be change in its mechanical properties than the properties by casting and machined part? What would be appropriate ...
2 votes
0 answers
35 views

Is a motor failure caused by a defect bearing considered to be a failure mode or is it higher vibration and speed loss in FMEA/FMECA?

Let us assume we have a motor with a bearing which is exhibited to wear. Over time, we can observe higher vibration, increased noise and the motor speed reduces due to the bearing fault. In the end, ...
2 votes
3 answers
660 views

DOE analysis or root cause analysis?

For any testing that a part is suppose to pass a test, let's say the leakage test of a seal flange. How should I individualize the cause? I know there is root cause analysis and for different ...
0 votes
2 answers
37 views

1m3 water container and ice damage prevention

I was looking for data on ice resistance for these kinds of 1000 litres containers. I believe they are made of polyethylene with an outside aluminium structure. Given the physics of ice expansion, ...
0 votes
1 answer
1k views

Can crosshead movement be used to measure strain in tensile testing instead of an extensometer?

I am trying to design and build a low cost tensile test machine for plastic specimens. Most machines I've seen measure strain data using an extensometer, either the clamp-on type or the noncontact ...
0 votes
1 answer
120 views

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 ...
0 votes
2 answers
104 views

Why don't car engine piston-rods (or similar parts) fail as often as other car parts?

Anyone who has owned a car has ultimately dealt with failure of a sensor (parking), or A/C failure, battery shutdown or a tyre puncture. Part breakdowns like these are pretty common, at least ...
0 votes
2 answers
730 views

Hollow Steel Tubing: Critical Load for Sidewall Buckling

I'm looking to construct a something with hollow steel tubing (e.g. 10ga 2"x3" rectangular tubing) suspended horizontally welded to an outer frame on both sides. I've already calculated the ...
0 votes
3 answers
227 views

Ductile,Brittle and Malleable

In Callister it says, "two modes of failure are possible ductile and brittle." Why not malleable?Furthermore why is uniaxial tensile test chosen for predicting failure?
1 vote
1 answer
74 views

Historical data for using supervised learning algorithm in the field of Mechanical Engineering [closed]

Being a student in the field of Mechanical Engineering, I am very new to Machine Learning.I did a couple of basic online courses of Machine Learning (including the one by Andrew Ng on Coursera). So, I ...
1 vote
1 answer
556 views

Hardening and Brittleness

Why is hardening and brittle nature so related?What is work hardening or strain hardening as far as true stress strain diagram is concerned?
1 vote
2 answers
40 views

Switch at the back of a battery eliminator

I have this variable voltage battery eliminator and the "switch" to hold the wire in place is broken. Is there any specific name for this "switch" and can I buy it somewhere to replace it or can you ...
2 votes
4 answers
14k views

What is the difference between tau = VQ/It and tau = V/A?

What is the difference between the formulas $\tau = VQ/It$ and $\tau = V/A$ for finding shear stress due to transverse loading? I understand that the use of first moment of area, is the only reason ...
0 votes
0 answers
102 views

Long term deflection

I've been working with a team of 'designers' that are highly concerned over a potential failure mode of ABS plastic. Their theory is that under a static load well under the yield point of the material ...
4 votes
1 answer
58 views

How to apply static failure criteria for bending stress in an angled cylindrical surface?

Let’s say I have an irregularly shaped bearing with a cross section that looks like the angled surface of a conical frustum, shown below. If a bending moment is applied which causes the inside ...
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0 answers
63 views

Plastic failure evaluation of steel using FEM

I would like to evaluate failure in steel using FEM, especially in geometries with stress concentrations (notches etc.). One possibility is to calculate the stress distribution using a purely linear ...
3 votes
1 answer
3k views

Actual amount of reinforcement gained by adding gusset to welded steel tube construction

This question bothers me for quite a while and is about bicycle frame construction, specifically a BMX frame and even more specifically it's front triangle. It is a heavy duty frame by definition, and ...
1 vote
1 answer
111 views

How thick of an oxide might form on a cast zinc part?

I'm looking into possible failures of a cast zinc part. I'm wondering if the Zinc-oxide that develops after a time would have a thickness great enough to cause dimensional tolerancing issues? ...
1 vote
0 answers
54 views

Column Buckling: Which is more useful to plot; Buckling Load vs Slender Ratio, or, Stress vs Slender Ratio [closed]

Both have a linear relationship, is there any merit in plotting one over the other?
0 votes
1 answer
44 views

Temperature vs Material Properties - ABS

I'm working on a design that uses fairly large plastic components (ABS, ~400mm longest dimensions). I'm looking at adding a steel component that encapsulates this plastic part. And, the steel part ...
3 votes
2 answers
3k views

Strength of Welded Joints

When calculating the factor of safety for a fillet weld that is loaded in shear what should be the maximum allowable stress? Some books suggest using the distortion energy (Ssy = 0.577Sy for the ...
3 votes
1 answer
49 views

Behavior of materials on application of tension

Does a test body subjected to a strain that causes plastic deformation still have elastic recovery?
1 vote
1 answer
745 views

Coconut Climbing Machine Ideas [closed]

I have been trying to create a machine to climb coconuts as the existing machines are very slow and strenuous to use and frankly, most climbers prefer to climb it manually than use the existing ...