Questions tagged [mechanical-engineering]

Questions within the problem domain of mechanical engineering. Mechanical Engineering can be a broad field; consider choosing more specific tags if they apply.

Suitable questions for this tag

As it is a basic engineering discipline this tag can cover many questions. However in order to use this tag the question should be about a mechanical system or machinery. Below is a brief outline about topics covered by mechanical engineering.

Overview of Mechanical Engineering

Mechanical Engineering is engineering field that deals with:

  • design
  • analysis
  • production
  • operation and
  • maintenance of

mechanical systems and machinery

Examples of these mechanical systems and machinery are manufacturing machines, heating and cooling systems, aircraft, watercraft, weapons, medical devices and machinery, robotics, automobiles, rolling stock, fluid systems.

Scope of Mechanical Engineering

Mechanical Engineering fields of study can be summarized as:

  • Mechanics
    • Statics
    • Dynamics
    • Mechanics of Materials
    • Fluid Mechanics
    • Kinematics
    • Continuum Mechanics
  • Mechatronics and robotics
    • Micro Electromechanic Systems (MEMS)
    • Control System Design
  • Structural Analysis
    • Failure Analysis
    • Fatigue Analysis
  • Thermodynamics and thermo-science
    • Heat Transfer
    • Thermofluids
    • Energy Conversion
    • Heating Ventilation and Air Conditioning (HVAC)
  • Design and Drafting
    • Computer Aided Design (CAD)
    • Computer Aided Manufacturing (CAM)
    • Finite Element Analysis (FEA)
    • Computational Fluid Dynamics (CFD)

Mechanical Engineering and other fields

Because mechanical engineering covers a vast area of knowledge, it overlaps with many basic science and engineering disciplines with varying amounts. These are:

  • Physics
  • Chemistry
  • Materials Science
  • Electrical and Electronics Engineering
  • Aerospace Engineering
  • Chemical Engineering
  • Metallurgical Engineering
  • Civil Engineering
  • Biomedical Engineering
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Is it possible for a bicycle chainwheel to have a fractional number of teeth?

Background In the world of bicycle motocross, also known as BMX racing, gearing is a hotly-debated topic. Since the bikes are all single-speed, gear ratio is a fixed number defined as chainwheel / cog (front gear divided by rear gear). Altering your…
eckza
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What is the purpose of these diversions in a natural gas line?

The campus where I work has a long covered walkway (~.5 mile) which has several labeled pipes running under the roof (chilled water, fuel oil, air...). All of the pipes run dead straight except for the natural gas lines, which have little loops…
Gretchen
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Why are railroad tank cars bent in the middle?

I recently noticed that the cylindrical shape of a railroad tank car is not completely straight but has a bend in the middle. The entire tank is a bit lower there. What's the reason for this bend? This is also visible on the drawing of a DOT 117…
Lukas_Skywalker
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Why are two wires used in railway overhead equipment?

While watching the train videos, I came across these overhead wires. After searching on the internet, I found that both catenary and contact wires carry the same voltage and are connected by vertical wires called "droppers" at intermediate points…
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Is it possible to build an air compressor with no moving parts?

Is it physically possible to build an air compressor with no moving parts? I'm envisioning a thermodynamic cycle capable of compressing air with no moving parts and operated in a stationary way. There is no limitation on the compression factor,…
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Why do hydraulic systems use special fluid - what's wrong with water?

As a hydraulics layman thinking about hydraulic systems, it seems that the important factor is to have a liquid that doesn't compress much or at all. Doesn't water meet this requirement, and what other properties should the liquid have (if any) that…
jhabbott
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How are increasingly accurate machines made?

Making extremely accurate machines seems like a chicken and egg problem. How do you make one if you don't already have one? For example, how was the first indexing head made without an indexing head to make the indexing plate? How was the first…
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Why are engine blocks so robust apart from containing high pressure?

Lately, I've been pondering why some engine blocks are so bulky, I always thought intuitively it was because they had to last a long time whilst containing thousands of combustion cycles but the more, I look into the reality of engine design that…
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Calculating pitch, yaw, and roll from mag, acc, and gyro data

I have an Arduino board with a 9 degree of freedom sensor, from which I must determine the pitch, yaw, and roll of the board. Here is an example of one set of data from the 9-DOF sensor: Accelerometer (m/s) $\text{Acc}_{X}$ = -5,85 $\text{Acc}_{Y}$…
MaltDew
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Why would you launch a large ship by dropping it sideways?

I'm referring to the process shown in this video: https://youtu.be/Quyr5R1Rbfw?t=20 Or this image from Wikipedia: In it, a large warship is launched into the water by essentially dropping it sideways down some ramps and off of a pier. The ship…
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Why does this fence have a kink?

The image below shows a style of fence that I've seen frequently around train tracks. If you look closely, you will see that between the third and fifth horizontal wire from the top, the vertical wires have a kink in them where they run diagonally…
Yly
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Understanding required torque for a motor lifting a weight

This is a continuation of me trying to understand torque and stepper motors in my other question. I'm trying to understand the torque a motor would be required to generate to lift a small weight, and the formulas involved. The first part of my…
confused
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Why don't hydroelectric plants use cascades of turbines instead of single turbines?

In a gas turbine engine there're multiple sets of blades - one set after another and combustion products pass all the sets and each set of blades gets some of the power. This increases utilization of power from burning gas. Meanwhile hydroelectric…
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Why exactly does a washer help distribute the stress around a bolt?

Usually the reason for having a washer under a bolt head is stated to be that it helps to evenly distribute the stress to the clamped material surface. But why is this? I would understand if the washer was significantly larger than the bolt head.…
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Why are rear wheels not placed at the extreme rear of a bus?

In some cars, I have noticed the rear wheels are located at the extreme rear of the vehicle. However, I have noticed that the rear wheels of buses are always located about 1/4th of the way forward from the rear. What is the reason for this?
Biju
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