Questions tagged [materials]

Use for questions about designing, manufacturing or synthesizing engineered materials or about the properties of specific materials. Questions concerning common construction materials, such as wood, steel or masonry do not need to use this tag; use the more specific tag instead.

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Would Amorphous Diamond-like Carbon coatings have a fatigue cycle limit?

I'm aware that polymers like most plastics can go through stress cycles indefinitely as long as the covalent bonds are not ruptured. On the other hand, I hear that even metals like steel and ...
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Precipitation Hardening

Please explain the meaning of this statement with close reference to Precipitation hardening,"The relative rates of nucleation and growth are controlled by temperature. The size and dispersion of the ...
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1answer
30 views

Seeking transparent, somewhat flexible material

Looking for a material that: Is transparent/clear - the clearer the better Can be made to about 80cm long x 8cm wide by somewhere between 2-5cm thick (likely 2-3cm, exact details will depend on the ...
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31 views

Metallic flow behavior under eccentric loading conditions

So, I did a quick search around and didn't seem to find anything regarding this, so I thought perhaps I should just ask a question. Metals are malleable and will generally flow/deform if you roll it ...
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52 views

Does the volume change under the tensile or compressive stress?

This confusion arise because my teacher says that volume does not change under tensile/compressive stress within the elastic limit of the material ( consider metal here). But as far as I can see via ...
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Why is it desirable to have high g value for sensing applications, while high d value is desirable for actuation in piezoelectricity?

In piezoelectric materials, two parameters are defined to construct relations between electrical and mechanical energy conversions. These parameters are the charge constant d and the charge constant g....
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Exact definition of ceramics

Exactly what are "ceramics"? I found a lot of similar "definitions" of that term online, e.g. on Wikipedia and here. These (and other) sources essentially state that ceramics are non-metallic, non-...
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What materials can be used for Brazing

I have trouble understanding the Brazing principle. What I know is that there are a couple of filler materials such as copper, silver, aluminim, etc.... What I remember from the past is that the ...
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2answers
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2nd Moment of Area of a ring

This is my first question here. I am having trouble finding the 2nd moment of area of a ring with a thickness 't' and radius 'r'. I seem to be a factor of 2 out. What I do is I consider an area like ...
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Why is there no widely-used standardized unit for indentation hardness?

The last hundred years have seen a great degree of standardization of units, and the expression of units of measurement in standardized, instrument-agnostic, objective terms, often in the SI units. ...
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How to estimate the elongation of a tensile test specimen fractured at the end

I'am a first year mechanical engineering student , i know that if the fracture doesn't happen in the middle of the specimen the test must be repeated , but they taught us a method to approximate the ...
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How good are graphene layers at shielding against ionizing radiation?

I assume every materials laboratory has ways to test properties of new materials. Has anyone ever tested graphene's properties at shielding ionizing radiations? I guess It could be a good candidate ...
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Measuring fracturability / airborne fuzziness of carbon fiber tow vs stainless steel tow

My friend uses carbon fiber tow in creating a component for automobile machines. However the carbon fiber is actually much tougher than it needs to be. As a risk manager in software I am concerned ...
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1answer
63 views

Seperating two glass pieces with a circuit board inside

I want to repair an outdoor lamp (see images below) however I can't get the glass container open. The methods I found on the internet are based on glue removers or based on heat but I'm not sure this ...
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28 views

(moulded) cast properties of the untreated surface

While my research about the untreated surface of moulded cast I read that the properties such as tensile strength, 0,2% proof stress and so on are different (much smaller) from the properties you can ...
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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 ...
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Designing a “ratcheting” spinning wheel with ferrous metal bits

I'm trying to design a freely spinning wheel that will "lock" into a few different configurations. I'm planning on placing a rare earth magnet near a certain point on the wheel, and inserting bits of ...
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Effect of annealing on the defects

What is the effect of annealing on the defects present in the sample? Does it remove defects in the sample? Is there any chance that due to annealing the point defects present in the sample combine to ...
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34 views

Ductility of Fe-Ni Alloy

Cold worked Fe-Ni rod is very brittle and not suitable for drawing. What would be the best heat treatment parameters for increasing the ductility of a Fe-Ni Alloy? Does increase in the Co content make ...
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Determining the minimal needed wall thickness between two bores in a control block

Given a control block of simplicity with only two bores. These two bores could be parallel or just could be very close to each other at a specific point in the control block. The material of the ...
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1answer
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Is it possible to cast copper around another metal

So i have seen these super conductor rods around (which appear to be copper around titanium/niobium). Now I am wondering (for a maker usecase) if its possible to create something similar by for ...
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Is there such a material that is resistant to torque while easily stretching when under torsion?

I need a shaft that can be stretched along its length while also being resistant to torque enough to be a functional shaft (see pictures). I have a rotating sphere within another rotating sphere, ...
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What is the difference between $K$ ,$K_{IC}$ and $K_t$?

I have seen three representation of stress concentration factor values $K$,$K_{IC}$ and $K_t$ now all that I know is $_I$ in suffix represents opening mode of crack.The suffix $t$ stands for tip....
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What's the most anisotropic material? Is there a dense stiffness matrix?

The stiffness (aka. tangent modulus of the stress) can be represented as a symmetric 6-by-6 matrix, i.e. it has 21 independent components in the most general case. In the linear case, this matrix is ...
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Silicone paste vs. silicone grease vs. silicone spray lube

For purposes of usage in home/auto and light industrial circumstances, what are the differences? What are the pros and cons, and suited uses, of each? Thanks!
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What material characteristics are most important for heating element material selection?

I want construct a heating element by screen printing a flat coil pattern of conductive paste onto an insulated substrate. This conductive paste consists of a powder of conductive metal contained in a ...
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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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Creep behavior in metals

If creep behavior can begin at 0.6T(melting) but, hot working for a pure metal starts at 0.4Tm, what is the explanation for this?
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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 ...
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Electric Current Based Shape-Memory Alloy

Would it be possible to create a piece of metal, made out of an alloy or combination of alloys, that undergoes a shape-memory-esque change in structure in reaction to an electric current? Could it ...
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Modulus of Rigidity (Shear Modulus) of string

Does anybody know of what magnitude should the Modulus Of Rigidity of a wool string should be? I know that neither wool or string are "materials" but if anybody can give me a rough estimate of a value ...
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Materials science and materials engineering

Good day, I would like to enquirer the followings: What is the difference between studying materials science and materials engineering? Are there any jobs exclusive to those who have studied ...
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1answer
28 views

bending rigidity of a metal rod

Say you have a metal rod with a square cross section (say 10cm by 10cm) of a certain length. You'd like to make it less prone to bending. Is it better to: keep it the way it is or remove material ...
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How do I calculate the compressive strength of a wall?

I literally just have a thin steel wall that stands vertically with a load on top. The thin edges of the wall are oriented vertically with the load applied on top of the top thin edge, with the large ...
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3answers
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Press brake tooling for 360 tube?

I’m trying to find out if it’s possibly to form a cylinder or tube with a diameter of 1 inch using some kind of curling die for a press brake. I’ve seen dies that make small 360 degree bends like that ...
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What do you think are the difficulties in tissue engineering of complex organs such as the heart and liver, as compared to skin?

What do you think are the difficulties in tissue engineering of complex organs such as the heart and liver, as compared to skin?
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Optimization of ash stockpile height to minimize haul truck fuel costs

How would I find out the optimum height of an ash stockpile in order to minimize diesel haulage costs, for a CAT haul truck? My stockpile height is required to be between 25m to 50m. I have worked ...
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Calculating thickness of steel rod to support x weight?

I am building a workout area and would like to include a pull-up bar. So I have two 6"x6" wood beams planted in the ground 10 feet apart and will drill holes through them and place a steel bar through ...
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is there any relationship between endurance limit and tensile strength for thermoplastics?

i want to know about the relationship between fatigue strength and tensile strength for thermoplastics especially PPSU (POLYPHENYLSULPHONE)@23 DEG.
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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 ...
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What is a material that allows air to pass but not water vapor?

What are some materials that allow air to pass but not, or to a lesser extent, water vapor? Here are two materials I am aware of: Teflon is a material that allows water vapor to pass, but not air. ...
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What happened to the projectile in Hypervelocity Impact tests?

I recently saw a tweet about Hypervelocity Impact Sample and someone ask how is it possible to shoot a projectile at that speed and what happened to the used projectile when hitting the shield. I ...
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1answer
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Carefully attaching Pt-wire to mild/carbon steel surface

Problem: I have a near 100% Pt wire (25 AWG / D ≈ 0.45mm) that I would like to attatch to a cold rolled steel (E235 / EN 1.0308) surface. Assume this surface is flat. Goal: Keep wire attached to ...
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What should be the material and thickness of front pillars to stop car (~1,847kg and ~262 km/h) without killing the driver?

"Tesla Model 3 owner died in a tragic accident with a semi truck. The Model 3 went under the truck’s trailer resulting “in the roof being sheared off as it passed underneath,” which is known as a “...
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Will a cyclic heat load transform my martensitic steel? How fast?

I have a plunger - that I'm using for glass forming - made out of a martensitic steel. Glass is at 1000°C and since martensite is a metastable phase, should I expect the properties of my plunger to ...
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How to write the equilibrium stress equations for a hollow, rectangular beam?

I have a system consisting of a hollow, rectangular cantilever beam (pictured below). I'd like to write the equilibrium stress equations à la the Cauchy Stress notation. How do I account for the ...
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Heat press of vinyl on 100% polyester fabric

I want to customise a piece of fabric that is 100% polyester (exclusive of decorations, wash at 30º) with vinyl. My idea is to use a vinyl cutter (such as Silver Bullet) to cut a pattern on the sheet, ...
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Material for filling small air leaks

Often beeswax is used to seal small air leaks on some musical instruments. One of the disadvantages of beeswax is that it has a melting point of around 140 degrees Fahrenheit and can therefore flow to ...
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Anyone facing issues with a compact roller press machine?

I am currently facing a problem with the machine above. When I try to compress something using the roller machine, sometimes my sample will have "scratch" marks after coming out. There are no foreign ...
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“bubbles” forming after heating my Thin film transistors

I am fabricating Bottom gate Thin-film-Transistors. The Gate is 60nm Molibdenum. The dielectric structure changes with the table below. The temperature represent the annealing temperature after ...