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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25
votes
3answers
90k views

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: ...
17
votes
3answers
40k views

Effective ways to drive a single shaft with multiple motors?

To head off the "why not use a bigger motor" question, I'm a high school mentor for an FTC (First Tech Challenge) robotics team, with a bit of a soft mechanical / hardware background. They're ...
20
votes
3answers
33k 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 ...
23
votes
1answer
74k views

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 ...
36
votes
2answers
17k 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 ...
12
votes
3answers
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 ...
7
votes
3answers
8k views

What is Radial and Thickness Mode Vibration in a Piezo Electric Ceramic Disc Transducer?

I am trying to use a Piezo Electric Ceramic Disc Transducer for ultrasonic sensing measurements for fluid levels. A Piezo Ceramic Disc with a Resonant frequency of 215 KHz or 1 MHz is under ...
4
votes
1answer
4k views

Why is the point of failure load lower than the peak load? [closed]

In a tensile test the peak load was 69kN, but the point of failure load was 60kN. Why is it lower?
10
votes
3answers
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 ...
4
votes
3answers
1k views

System curve for use in determining pump operating point

What is meant by a "system curve" that is used to determine the operating point of a pump. I know what a "pump curve" is, but I often hear about a "system curve" being generated so that the pump ...
3
votes
1answer
1k views

How to draw isometric view of this shape?

I'm having trouble drawing an isometric view of this shape: I've only just started an engineering course and so far it's involved a lot of drawing which I usually can do but I can't seem to figure ...
2
votes
1answer
6k views

Can Peltier Modules be practically used to cool a room?

I am thinking of building a indirect Peltier AC to cool a room of approx size 30m3. Single/multiple peltier modules will be used to cool a insulated box with water inside. The box will be kept outside ...
0
votes
1answer
247 views

Engineering Drawing-Projection of intersection curve of two standing cones

I have this projection of two intersecting cones, and I am asked to draw the intersection curve of the two cones on the projection. What is the right way to do it?
15
votes
3answers
246k views

How to calculate flow rate of water through a pipe?

If a water pipe is 15 mm diameter and the water pressure is 3 bar, assuming the pipe is open ended, is it possible to calculate the flow rate or water velocity in the pipe? Most of the calculations I ...
16
votes
4answers
4k views

How should I position two shelf supports for the best distribution of load?

I'd like to mount a shelf on the wall. I have two shelf supports to do so, like this: Relative to the shelf, where do I place the (blue) supports to achieve the best distribution of load?
12
votes
5answers
17k views

How to calculate lever force when lever has uniformed distributed load?

We have a simple class 1 lever: $$\begin {array}{c} \text {5,000 kg} \\ \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \...
5
votes
1answer
5k views

How do I calculate an estimate for the properties of a composite material?

For a given laminate made of composite material (composed of fibers oriented in a carefully designed sequence coated and embedded in a matrix material), where can I begin estimating the stiffness and/...
2
votes
3answers
2k views

Deflection of a cantilever beam composed of separate (not bonded) planks

In the case of a simple cantilever beam having a uniform shape and being loaded at its end - the calculation of the deflection at any point along the beam is well known. What happens if we split it ...
26
votes
4answers
3k views

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 ...
9
votes
1answer
4k views

Why don't we use principal maximum stresses when designing a structural element?

Consider a concrete column is under compression from top loading and also carries some shear stresses. If take a plane 2d element in the column with these stresses and rotate it to the point it gives ...
8
votes
2answers
7k views

How Can I Determine Multiple Discharges from a Pipe Network? (Knowing the Inlet Conditions)

I have little/no experience with pipe networks and have been searching for a methodology to calculate the discharge from multiple outlets of an oil pipe network with a single inlet. As far as i can ...
9
votes
9answers
6k views

How can "mpg" be high under low engine load?

Let's say a car at 60 mph requires roughly 20 hp to maintain its speed (i.e., to overcome rolling resistance and drag). If this car makes 240 hp and gets about 34 mpg (not too unrealistic), how is it ...
4
votes
1answer
3k views

How to calculate if a motor is capable for a load?

I am trying to figure out if a motor I have is capable of spinning a wheel. Here is all of the information I have: MOTOR: 190 g.cm min. WHEEL: 26 cm diameter, weighs about 59 grams I imagine that I ...
9
votes
6answers
19k views

Steel selection for building a trailer

I'm thinking about building another trailer. I've built lots of smaller trailers in the past, but this time I'd like to build myself a small tandem axle gooseneck rated for 7,500 lbs. I am a ...
8
votes
2answers
8k views

Interpretation of shear flow/shear center of L-profile

I have calculated the shear flows and center of an L shaped profile. I assume they are correctly calculated (I followed the same steps as during the lectures for an I shaped profile). However, I have ...
7
votes
4answers
2k views

What are the common failure points of waterproof cases?

I am making a waterproof case for my Galaxy S5 and/or my Raspberry Pi. I plan to make the main body from (or at least decorate it with) wood, though I can use other, stronger materials where needed. ...
4
votes
2answers
548 views

Can a Peltier's device (i.e.Thermoelectric cooler) achieve cryogenic temperature efficiently?

Does the stacking of peltiers device shows promising results in achieving the cryogenic temperature? I have tried doing the experiment, the overall temperature of the system increased around 80ºC and ...
2
votes
2answers
4k views

Torque required to launch a tennis ball

I am trying to find out if the 12 V DC electric motors that I have are powerful enough to launch a 100 g tennis ball 30 m away. The tennis ball is put down a pipe and ends up wedged in ...
1
vote
0answers
91 views

Will high velocity air directed underneath a half-toroid shaped Coanda saucer by a centrifugal impeller create a lifting force?

I would like to know if a lifting force will be created by the Coanda effect from high velocity air that is directed underneath a half-toroid shaped saucer by a centrifugal impeller. I am seeking an ...
9
votes
2answers
248 views

Why does reducing the amount of emissions control improve the fuel economy of a car?

In addition to power and performance, one of the reasons VW cheated their emissions results was to improve the fuel economy of their cars. Why exactly does this happen? I'm familiar with cars and how ...
7
votes
4answers
324 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?
7
votes
2answers
956 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 ...
6
votes
5answers
991 views

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 ...
4
votes
3answers
329 views

What causes Rolling Resistance?

I am currently reading “Fundamentals Of Vehicle Dynamics” by Thomas D. Gillespie. The author mentions how the asymmetric pressure distribution across the length of the contact patch of a tire while ...
4
votes
1answer
73 views

How to reconfigure a control box unit for an SCN5 actuator

An image of the actuator is below. I have a setup that was given to me where there is two configurations, namely 50mm travel and back, and 75mm travel and back to home position. There are two switches ...
4
votes
1answer
869 views

Why is the Stress vs strain diagram preferable to the Load vs displacement diagram?

I’m really unsure what is the difference between stress vs. strain and load vs displacement graphs and why stress-strain is better. I know that the units are different: stress is in MPa and the load ...
4
votes
2answers
3k views

How does the central lock mechanism in articulated arm (magic arm) works?

does anyone know how does the central lock mechanism in articulated arm (magic arm) works? The magic arm usually used to hold camera, with only 1 knob, it can lock all sides. How?
3
votes
3answers
575 views

Would a structurally sound pressure cooker be able to withstand an internal vacuum?

Would the body of a normal round pot shaped pressure cooker (built to cook foods at 15 psi) be able to withstand being evacuated down to high-vacuum pressures? Apparently it has been done before: i.e....
1
vote
0answers
93 views

Is it possible to create a hard slick non-stick non-degradable substance? [closed]

I once read on a web page I can no longer find that corundum is a covalent network. I'm guessing that's because despite the fact that the electronegativity difference between aluminum and oxygen is ...
1
vote
1answer
108 views

Calculating Minimum Pipe Pressure Requirement for an Irrigation System

I am setting up an irrigation system for my ranch and I have a hard time calculating the minimum pipe pressure requirements to reduce cost. I need to know the maximum pressure the pipe has to cope ...
1
vote
2answers
36 views

Is stroboscope a useful device to control the translational vibrations?

There is few material on net related to stroboscope applications. since it is an optical device, it is best used to control the vibrations of rotary devices like turbine blades electromotors etc. but ...
0
votes
0answers
42 views

Continues beam deflection

does any one know how to derive the deflection equation of a continues beam of three span of equal length and equal UDL load Here's a link these two pictures shows my tries to solve the question
0
votes
2answers
2k views

angle of twist of gear relative to another gear

why the torque is negative in this case ? the question ask for determine the angle of twist of gear C with respect to B . We have to 'fix' the B , and determine the twist of C ? So , imagine that we ...
0
votes
2answers
63 views

producing vibration motion of a plate (1cmx2cm) placed in water

In order to conduct a study, I need to place a rectangular plate freely placed (1 cm by 2cm) inside water and control it from outside (better wireless). I need to give oscillatory motion with specific ...
0
votes
1answer
1k views

Tau max value in torsion calculation [duplicate]

I am going to try and ask this question again. In this formula to calculate shear stress in a solid shaft: τ = T r / J If I want to solve for the radius; I should use the modulus of rigidity ...
-2
votes
1answer
51 views

what should be the size of gate? [closed]

what should be the size of gate? if street 8 ft according to house map Car entrance gate 11 ft can corolla grande car enter into the gate easily with some moves?
28
votes
10answers
7k views

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 ...
10
votes
4answers
23k views

Why does the stress-strain curve decrease?

This is a stress-strain diagram I have noticed that the curve decreases between points C & D and between E & F. Why does that happen? I expected the curve to always increase since the ...
23
votes
5answers
5k views

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 ...
44
votes
9answers
8k views

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 ...