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1500 questions
6
votes
1 answer
How do the dimensions of a ductile iron casting change as it cools?
I am designing a pattern for a sand casting. It has only one critical dimension which is a 4" inner diameter cylinder. If I use a 4" core, will the casting shrink away from the core? In other words will the inner diameter of the cylinder end up…
Wallace Park
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6
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1 answer
What is the relevant ISO or similar standard to refer to for painted metal corrosion testing?
We have an electronic display product that will be installed in a street side application. The front part is made from metal and exposed to the elements so it will need to be painted to protect it from corrosion.
Does anyone know what would be a…
Jonathan
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6
votes
2 answers
How to indicate bolt direction on a drawing?
Consider the following steelwork drawing:
The location of the 6 no. M12 bolts are indicated with a circle and cross.
However, it is not clear whether the shank of the bolts should point into or out of the page. Without explicitly drawing the nut…
egg
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6
votes
5 answers
Ways to brake an axle
I am currently studying Mechanical Engineering and am doing an assignment where I have to design a wire rope tensioner where a wire rope is unspooled from a drum, but the wire has to be at a specific tension when unspooling. Therefore I am looking…
David
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6
votes
1 answer
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?
Sina M
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6
votes
2 answers
What are the pros and cons of using Zibgee over BLE or vice versa for IOT application?
I am currently working on develop an IOT architecture. The sensing devices are to be integrated with microcontroller. The microcontroller will be integrated to some type of RF communication device. As the community is well aware RF communication…
Mahendra Gunawardena
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6
votes
1 answer
Multi-gas barometric height formula in isotope separation devices?
What is the barometric height formula for a mixture of gases?
The main problem I can see, the curves describing the minimal energy (kinetic + gravitational/centrifugal) won't be any more a simple derivative, but a functional equation.
I think, this…
peterh
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6
votes
1 answer
Why are words bit-shifted for an Atmel SAM4S SPI slave?
I have discovered a problem when using the SPI peripheral in slave mode on an Atmel SAM4S. Occasionally words can become bit-shifted. I can force this condition by enabling the peripheral some number of clocks after NSS goes active. I do this by…
Patrick
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6
votes
1 answer
How to calculate the adhesion I need to keep a 3D printed bending part straight?
3D printed parts cool down during printing, resulting in thermal contraction which causes a bending moment and separation from the printing bed.
The issue is solved by increasing adhesion to the printing bed, which however results in more stresses…
FarO
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6
votes
2 answers
How to find who occupies pin X in Device Tree?
I've already learned how to find which pins can be assigned to a functionality I just open the [arch]-pinfunc.h file and find the entries after __ for given functionality and then find the pin that provides it, left of the __ in the entry. Then I…
SF.
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0 answers
Calculating the bending moment ($M$) of a beam as it relates to stress ($σ$) and strain ($ε$)?
I am trying to learn how to work out the bending moment for progressively complex systems to model a beam. I am assuming only one axis of motion (transverse = $y$).
For the basic equation of material elasticity, $σ$ represents stress and $ε$…
mike
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6
votes
4 answers
How do dry storage cabinets work?
In my lab we use a number of materials which are hygroscopic and must therefore be stored in a dry environment. For that purpose we have numerous dry cabinets very similar to the one shown below (Amazon link here).
These cabinets run on…
Chris Mueller
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6
votes
3 answers
How can the vendor be approved/disapproved based on validation test data?
The power requirement for a sub system is 5V +/- 10% @ 1A of current. A RFQ was issued and a prospect vendor was selected. A first article of inspection (FAIR) has been submitted which includes 15 power supply samples. The samples have been tested…
Mahendra Gunawardena
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6
votes
4 answers
Precision measurement of liquid levels
How can I measure changes in liquid level of the order of 50 μm?
The tank is cylindrical with a radius of about 12.5 mm and a total volume of about 45 ml. The fluid is water-based. The technique needs to be optical or similar because no external…
Worldsheep
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6
votes
2 answers
Yield properties of plastic material
What is meant by yield of isotropic plastic material?
How is yield of Isotropic plastic material different from the term normal yield which is referred as transition from elastic behaviour to plastic. I am bit confused of term Yield of Isotropic…
John
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