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.

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What is the maximum length of oil pipelines?

This is inspired by the discussion and controversy surrounding the Keystone Pipeline. The main part of the Keystone Pipeline system is about 3,400 kilometers long, stretching across a large portion ...
HDE 226868's user avatar
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8 votes
3 answers
5k views

How to seal a pressure vessel

I'm trying to construct a stainless steel high pressure containment vessel (pressure reactor) (2000 psi or so). Yes I realize that this is a don't try this at home type of thing, and I plan to put ...
user379468's user avatar
6 votes
1 answer
2k views

How is fuel mixed with air in a jet engine?

I am working on an idea that involves a jet engine, but I don't quite know how the fuel system works. In a combustion engine like that in a car, you have nozzles that spray the fuel into the piston ...
cluemein's user avatar
  • 163
20 votes
6 answers
7k views

Why don't refrigerators have parts outdoors?

I've always wondered why refrigerators don't have some of their parts located outdoors like an air conditioner. In warm weather, it seems like it would make sense to have the condenser outside like ...
Justin Trzeciak's user avatar
7 votes
2 answers
400 views

Could magnetic levitation transportation systems become a commonplace technology?

Magnetic levitation systems of transportation such as trains seem to be commonplace in early 2000's science fiction, and while some systems exist currently, they aren't exactly common. It seems to me ...
Sam Weston's user avatar
13 votes
1 answer
433 views

Estimating whether the flow through a valve or nozzle cavitates

My understanding is that cavitation occurs in the flow of a liquid when the static pressure drops below the vapor pressure, even intermittently. So even if the time-averaged static pressure (what you ...
Ben Trettel's user avatar
5 votes
2 answers
11k views

Finding the pull-through capacity of a nutted bolt and washer in ASA plastic

I have a uniform load applied to the underside of a plastic sheet which is to be resisted by the combination of a bolt, washer, and nut as depicted below (the other end of the bolt is secured and will ...
Rick's user avatar
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3 votes
2 answers
7k views

How to Compute Total Strength of Composite Tensile Bars

In this question about combined tensile strength, all of the tensile bars are of the same material. But what if the case that they are made of different materials? Say we have $200$ bars of $A=10 (\...
PdotWang's user avatar
  • 153
38 votes
2 answers
19k views

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 ...
Gretchen's user avatar
  • 483
8 votes
1 answer
187 views

Scale models of thermal plumes

I want to look at the thermal heat plume of a human in still air in a room. So I have a tank of water with a heating coil/cylinder in it. How do I calculate what the heat output of my heating coil ...
HCAI's user avatar
  • 205
3 votes
1 answer
208 views

How to divert solids from a downward vertical pipe

I am an electronics engineer trying to build one small underwater mechanical device (about 12 cubic cm) as part of a personal automation project. I have figured out the electronics for this, but I am ...
Praval's user avatar
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22 votes
4 answers
8k views

What is a reason that handlebars fit to a motorcycle and steering wheel fit to a car?

What is the reason that handlebars are installed on motorcycles and steering wheels are installed on cars? Notice that the way to use both handlebars and steering wheels are quite similar, but a ...
fronthem's user avatar
  • 465
4 votes
1 answer
2k views

Tankless air compressor for electronics desoldering station

I purchased a Weller WSD161V soldering station (similar to this one, at least with regards to the pneumatic system I'm about to describe -- sorry, I was unable to find a manual for my specific model ...
swineone's user avatar
  • 141
6 votes
1 answer
127 views

Where to insulate Underfloor air distribution system in a temperate climate

I have a proposed underfloor air distribution system (UFAD) for a one level office in a temperate climate. Typically the demand for heating and cooling in this climate is about even for offices. ...
pandita's user avatar
  • 377
5 votes
1 answer
187 views

Name of spring actuated component

I need to get another component like this but I can't seem to find any manufacturers / retailers. To describe it: It is spring mounted on a shaft and retained by bushing on the top and an enlarged ...
Eduards's user avatar
  • 61
8 votes
5 answers
8k views

How do you attach something temporary to a smooth metal shaft?

I want to attach something small to the smooth metal shaft of a small motor (2-3 mm in diameter), like fan blades, but I want it to be temporary. If I make it too loose, then the fan won't turn at ...
Pyraminx's user avatar
  • 301
7 votes
2 answers
1k views

Creating smooth shaft resistance

I am trying to emulate the resistance of a hand wheel which moves a table via a series of shafts and chains which turn an acme screw. I am switching to a CNC system that will allow the user to keep ...
Mister Tea's user avatar
6 votes
3 answers
1k views

Mounting and Coupling an Encoder

I was wondering how to mount a small rotary encoder to a platform in order to measure how far a small treaded robot has traveled. We're using this tread/wheel set: We've tried epoxying the encoder ...
rasz's user avatar
  • 93
2 votes
2 answers
623 views

Possible Hazards of Software Controlled Systems (Ex. Airline GPS/Elevator)?

I am currently reading through a book on Software Engineering principles, with a lot of the content having to do with proper approaches to software development methodologies and project management ...
Analytic Lunatic's user avatar
8 votes
2 answers
1k views

How do I form a budget for a mechanical research project?

I'm a mechatronics engineering student currently on workplacement. I've put forward a research proposal to develop an improved mechanical gripper used for automated product handling. The company likes ...
Sam Weston's user avatar
7 votes
2 answers
226 views

Cutting mechanism for a robot in confined spaces

I'd like to build an exploratory robot that can fit within confined spaces1. As the robot moves along the inside of a 4" pipe, it's likely to encounter some obstacles that need to be removed. ...
user avatar
2 votes
2 answers
751 views

Final speed of a truck on a slope?

I have a truck which weighs 190 kg and will travel 100m down a 38° slope. How I can find the trucks speed at the end of the 100m?
Guillaume's user avatar
7 votes
2 answers
134 views

Traction mechanisms for a robot in confined spaces

I'd like to build an exploratory robot that can fit within confined spaces1. What traction mechanisms should I consider to propel a robot along the inside of a 4" pipe? The pipe to be traversed will ...
user avatar
3 votes
1 answer
142 views

What is the name of the part that allows a steam wand to have a moveable joint?

On espresso machines, there is some kind of pipe joint which allows the steam wand to move while maintaining its seal. What is this component called?
caleb's user avatar
  • 133
8 votes
1 answer
306 views

Controlling hydraulic cylinders with variable delay

Electro-mechanical systems typically used in robots have very low delays and are quite simple to build servo controllers for. Hydraulic systems are much less common in robotics and have delay due to ...
kerblogglobel's user avatar
3 votes
2 answers
3k views

What are the longitudal tolerances of thread on metric nuts and bolts?

It's not exactly my area of expertize and I've spent a couple hours ears deep in norms, and I'm not really sure if what I found is correct (the figure I found was to the order of 1$\mu$m). When using ...
SF.'s user avatar
  • 6,105
12 votes
3 answers
1k views

Thermoelectric Technology to Harvest Energy from Internal Combustions Engines

Background: In an automobile, only 1/3 of the potential energy in the fuel is converted into mechanical energy and significant portion of the energy is lost as heat. There have been previous ...
Mahendra Gunawardena's user avatar
10 votes
3 answers
2k views

Harvesting thermoelectric energy from computer graphics cards

During CES2015 a well know Graphic Processor Unit (GPU) manufacturer introduced a new GPU. These GPUs need complex thermal management to keep the processor cool. Most GPU accelerator card ...
Mahendra Gunawardena's user avatar
12 votes
4 answers
10k views

How do I calculate the forces on a desk and its legs?

I have a design for a desk, and I'd like to not just guess at how strong it'll be, but I can't find an explanation on how to figure out all the forces involved that doesn't assume I already know a lot ...
mordac's user avatar
  • 121
12 votes
3 answers
5k views

Which turbulence models are suitable for CFD analysis on a streamlined vehicle body?

Many commercial and open-source CFD codes implement several closure methods for the non-linear convective acceleration term of the Reynolds-averaged Navier-Stokes (RANS) equations. Common methods (...
Paul Gessler's user avatar
6 votes
2 answers
382 views

How to size a heat exchanger for a shear thinning fluid?

To size a heat exchanger, I need to know (among other things) the Reynolds number (Re) as an indication of the flow conditions. The Re number depends on the viscosity. In a shear thinning fluid, I can'...
mart's user avatar
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14 votes
5 answers
857 views

Are pneumatic tires obsolete?

Adaptive suspensions with adjustment rates on the order of milliseconds are going mainstream in consumer vehicles. Air suspensions have been common on commercial trucks and some SUVs for some time. ...
feetwet's user avatar
  • 1,757
2 votes
2 answers
342 views

Most efficient heat exchanger for dirty air/water medium?

It's been a long time since I went over heat exchangers and even then it was all theoretical. I'm looking for anyone with real world experience with different types of heat exchangers. I'm looking at ...
JedF's user avatar
  • 476
7 votes
5 answers
7k views

How can I improve traction on a wheeled vehicle yet reduce friction?

This is inspired by a project I undertook for my Physics class last year; I'd like to apply it in the future. Background: For the project, I and a few classmates were required to build a small car ...
HDE 226868's user avatar
  • 2,475
7 votes
1 answer
922 views

What are the benefits of a diaphragm pump vs a simplex pump?

What are the benefits of a diaphragm pump over a simplex pump? Is there any specific design criteria that should be used/stated in an engineering specification for a diaphragm pump?
Christie Clayton's user avatar
28 votes
4 answers
31k views

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 ...
jhabbott's user avatar
  • 5,960
13 votes
4 answers
1k views

Easy nonlinear model for large deformation of a beam

I have a beam subject to twisting and/or bending forces as well as linear compression force along its main axis. It is modelled as an isotropic beam, but if anisotropic is not too far off then that's ...
imacube's user avatar
  • 331
20 votes
1 answer
526 views

Sizing a pressure safety valve for two-phase flow

I understand that valves in two-phase vapour / liquid were sometimes sized by considering the required vapour and liquid flow rates separately, and then adding the results together. But this is now ...
SecondVector's user avatar
13 votes
3 answers
10k views

How different are dc motor designs from dc generator designs?

Some dc motors can be used as generators as well by applying mechanical torque to the output shaft to induce a current. However, even if a dc motor can do this, I imagine they were not designed for ...
Paul's user avatar
  • 2,569
8 votes
2 answers
9k views

How to calculate the pressure a pipe can withstand?

I was looking at high pressure pipes and their pressure ratings. I'd like to know how these pressure ratings are determined. I assume that pipes are tested until failure, and the failure pressure is ...
jhabbott's user avatar
  • 5,960
-1 votes
1 answer
816 views

Can Mechanical Design help meet EMC/EMI requirements for electronic products?

EMI/EMC issues are common in most electronic designs. Electronic and Hardware Engineers use many different strategies to mitigate these issues: These include (But not limited too) Designing filter ...
Mahendra Gunawardena's user avatar
1 vote
2 answers
5k views

What are characteristic values for a piston pump?

For a piston pump you can calculate/measure things like, Average Volume flow rate (m³/s) Geometric Values (Surface) Pressure over time closing times of the valves energy conversion efficiency $\eta$ ...
JHK's user avatar
  • 1,618
11 votes
1 answer
3k views

Detailed dimensions of an aircraft engine compressor blade

I am working on rub-induced vibrations in compressor stages of aircraft engines. The work is carried out in partnership with a company, therefore there is a limited amount of it that could be ...
Nicolas's user avatar
  • 332
12 votes
5 answers
3k views

Determining Drill Speed

How are spindle speeds calculated for a drill bit? I've seen dozens of charts that highlight the rpm that should be used for specific drill bit types, bit diameter, and material. However, what if my ...
Justin Trzeciak's user avatar
5 votes
1 answer
759 views

What are the predominant types of concrete pumps and what are their working mechanisms?

I've looked around for different types of concrete pumps and simply don't know if there are many different types, what their mechanisms are and which ones are the most predominant ones. What I've ...
JHK's user avatar
  • 1,618
8 votes
1 answer
1k views

How can I calculate the stresses and limits for the physical lowering of in-service pipelines?

Sometimes underground pipelines are exposed due to vertical scour or lateral migration of streams (or other erosion). One option is to lower the (in-service) pipeline to a new depth that provides ...
JustInTheWoods's user avatar
7 votes
5 answers
702 views

How can we prevent/detect hydrogen embrittlement?

There has recently been a series of high profile bolt failures on 'The Cheesegrater' in London, which have been attributed to hydrogen embrittlement. What can engineers do to ensure that hydrogen ...
thomasmichaelwallace's user avatar
21 votes
3 answers
38k views

How does width and thickness affect the stiffness of steel plate?

I have a 2 mm thick steel plate which is 300 mm long and 30 mm wide, supported at either end. It supports a weight-bearing wheel that can roll along the plate. It currently supports the maximum weight ...
jhabbott's user avatar
  • 5,960
10 votes
4 answers
1k views

Preventing condensate backup at startup with orifice (venturi) steam traps on medium pressure batch process mains?

I am working with 1" medium pressure steam mains (45 psig) for a batch process. Time between batches is usually short (to the order of minutes) but depending on the day the delay can be hours, and ...
jmac's user avatar
  • 242
13 votes
4 answers
2k views

In aluminum machining, what are the most common factors that might cause a machined component to have warping issues?

I am currently having an issue where features of my machined parts are warping. I am using Alloy 7050 Type I and Type III in this particular case. Using a feeler gauge and a certified, calibrated ...
Tim D's user avatar
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