# 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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### How to solve transient heat conduction equation at a point in space with volumetric heat source?

My system is a fluid exposed to light and I want to calculate the temperature change with time at a point, hence there are no spatial effects or convection due to the flow of the fluid. The heat ...
12 views

### Constant-force actuator for a lifting plate

Thank you for this forum. I am writing here because I struggle with a mechanics problem. I am designing a lifting device for heavy charges. The load (F) is applied to a top plate. I would like this ...
36 views

### Relation between welding bead and outer diameter of a pipe?

How can we find a relation between welding bead and outer diameter of a pipe? Welding bead is inside of the pipe and I am using M.S. pipe. Dimensions are listed below: Pipe OD=25.4mm Thickness=2mm ...
11 views

### Whirl and angular speed of Jeffcott rotor model

So it just doesnt make sense for me that ω and dθ/dt angular speeds can be different.(My book states that it can and it usually is) It doesnt make sense simply because harmonic excitation doesnt ...
• 1
19 views

### How to control a Stepper Motor with CircuitPython?

So I am using a Seeeduino XIAO as my microcontroller which then connects to a ULN2003 board connected to a 28byj48 Stepper Motor. I have wired the Digital I/O pins from the XIAO as D1 -> In1 D2 -&...
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23 views

### how to determine the direction of support reactions in a truss?

Hi, I am not sure how to determine the direction of support reactions at point A and K. I know point A has a pin support, therefore, it can take in horizontal and vertical loads and point K has a ...
1 vote
114 views

### Industrial (Farming) high precision gps tracking solution [closed]

Context: I am a hobbyist and I don't have experience with industrial solutions I am starting to prototype a farming equipment gps guiding system and I was looking fore some feedback regarding my ...
32 views

### What is the mechano-acoustic effect of off-centering the black paste on tabla-drum skins?

Tabla is a musical instrument composed of two drums, the Bayan (left on picture) and the Dayan (right on picture). A unique feature of the tabla is the tuning [black] paste called the gab, applied to ...
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20 views

### How is the ABAQUS solver used for contact mechanics different from the COMSOL solver? [closed]

I want to model the stresses and deformations for a contact mechanics problem involving contact between 2 multi-layered materials. I have read at some places that Abaqus is better than Comsol for this,...
1 vote
54 views

### Airflow visible over the airplane wing

What's that visible airflow over the airplane wing and what causes it?
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### Why is Scotch-Yoke mechanism not used for internal combustion reciprocating piston engines?

Regarding piston acceleration variations due to the geometric nature of crankshaft and connecting rod motion, in relation to connecting rod length and bore to stroke ratio. Why is Scotch-Yoke ...
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71 views

### Understanding physics principals behind machining

I am a mechanical engineering student and I want to design a desktop machining lathe for light polymers and soft metals. I am in my second year of course work, so I am unsure of how to go about ...
36 views

### How to calculate elastic deformation due to kinetic energy (impulse)?

I am a Mechanical Engineering student and I am a little confused on how to find deformation of a material given an amount of energy. I have a mass falling from a certain height to punch an indent into ...
58 views

### How to calculate the magnetic force for metal on magnets?

I am currently trying to hold a metal block in place with the magnets shown in the layout below. These magnets are permanent magnets which both expose one of their poles on the top side as shown below....
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1 vote
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### Why would you put covers in front of the output of the condenser fan on these mini-split units?

Seems like this would be bad for airflow and hurt efficiency? I'd think you would want to blow that hot exhaust air as far away from the intake as possible, and with as little static pressure as ...
• 111
38 views

### What is the safe rpm limit for a solid steel wheel

What is the safe rpm limit for a solid mild steel wheel. Outside diameter equals 16.564” thickness equals 3.862” Inside dia. Is 2.56”. The wheel is supported by a tapered hub onto a shaft. The hub ...
7k views

### Why is this bridge thickest above the support pillars instead of the mid-span where the bending stress is highest?

Why is a bridge designed like this? The depth of the section at pillars is more than the depth at middle. If I model this as a simply supported beam having load at mid span then the bending moment ...
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1 vote
111 views

### Is there a way of "shortening" a mechanical lever, but keeping its mechanical advantage intact someway?

For what I think I know, the mechanical advantage of a lever comes in exchange for the distance the load travels upwards, independent from the type of lever (I think). So, let's say, in a (class-1) ...
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54 views

### Could a hybrid system of mechanical levers and hydrostatic/hydraulic cylinders be able to lift 200+ kg with the force of an arm?

I don't know much about levers and hydrostatic/hydraulics myself, so I hope I don't make too many misconceptions. The idea: Hypothetically, if you had a 40km+ long indestructible lever on a ...
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213 views

### Torque Problems vs Motor Problem?

I want to preface this by saying I am software engineer so each part of this robot build has been a lesson on its own. From welding, to CAD design, pillow block bearings, etc, etc.... I am working ...
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48 views

### Calculations of a sphere

I apologize if the question is very basic, I admit I'm not the best at math and physics. I am doing an experiment with a sphere, the measurements are as follows: The sphere has a diameter of 330 mm (...
83 views

### On a car with all-wheel drive, how does the engine provide the angled front wheels with power?

Obviously, a single solid axle connected straight through the wheels would bend if the wheels to which is was connected were to rotate right or left with respect to a vertical line (i.e. be steered). ...
662 views

### Direction of fluid flow

Consider water flowing in a pipe, and I don't know the direction of flow. How to determine the direction of flow? My approach- I can use a pitot tube but for that I have to drill a hole in the pipe ...
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7 views

### Why selecting "Flange, Extends To" doesn't accept a Face but requires a Point or Vertex?

I am following the Advanced Modelling for Mechanical Design Course of Autodesk Inventor. In one of the videos LINK there's the following question: What geometry must be selected when using the Flange ...
1 vote
46 views

### Where can I buy industry quality ready prototype construction set? [closed]

I am designing a mechanical machine. I have constructed it successfully using children's construction set like Merkur. The machine I made makes a lot of rotation. Consequently, the children's ...
28 views

### Determining the angle theta at the Mohr's Circle

I'm having trouble about deciding the initial angle theta before drawing the Mohr's circle. From what I've learned from the lecture, I need to draw a normal line of indicated plane and find the angle ...
47 views

### Flow of fluid in branched pipes

Could any one please tell me if there is any flow possible into pipe 2. What I believe is that as pipe 1 and pipe 3 are of same diameter and applying Bernoulli's equation between points 1 and 3 gives ...
44 views

### How to split power from a single DC source?

Basically I would like to power a Seeeduino Xiao (basically an Arduino board that accepts 3.3V) and a 28BYJ-48 stepper motor via a ULN2003 Board (which accepts 5V). I was thinking of using a single 9V ...
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27 views

### Governors and acceleration effect on IC engine

If a car is moving with a constant velocity this means that resistive loads (like air drag friction) should equal the driving force from the car; but I know that the governors always cancel the effect ...
40 views

### How to design the thickness and diameter of a cantilever beam in bending for both composites and metals?

The goal is to find the optimum values of the diameter and the thickness of the circular cross-section of a cantilevered beam in bending, with the lowest weight (cross-sectional area). The main ...
41 views

### Ideal design for a long fruit plucking pole

I need to design a long (6-7m) pole for plucking fruits from tall trees. The following are the requirements: The pole material needs to be as light as possible. The pole should not be flexible ...
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1 vote
42 views

### What is the definition of depth of cut in machining?

Calculate the machining time required to reduce the shaft diameter by 6 mm if the maximum depth of cut is 2 mm, and also the parting off (cut off) time for the shaft, knowing that: the shaft diameter =...
40 views

### What's the difference between a four jaw independent chuck and a faceplate chuck

They both sound to me like the same thing what's the main difference between the 2 , Like something that one can make but the other can't ?
1 vote
43 views

### portable humidifier (balancing a bucket of water on a bicycle)

I built a (relatively) portable air-blowing device that purifies room-temperature ambient air (HEPA, carbon filter), and then heats and humidifies it to 37 °C and RH85%. I use the machine to do ...
44 views

### Wheel's torque and differential gearbox

I know that the differential gearbox is providing a torque to the wheels; as the relation in the figure indicates : Tw (wheel torque) = Td (differential torque) × (ηd×nd). Where nd:is the differential ...
44 views

### How to slow down an electric motor for pull cart?

I'm trying to retrofit an electric motor (such as this) to a pull cart as depicted below. I got most things figured out except for how to slow down the motor to a pedestrian speed. Could I slow it ...
73 views

### Will a (stainless steel) underwater gear, formed by a 1500 RPM pinion and a ring cogged wheel 20 time its diameter, work?

Fig. 1 shows a submerged experimental electric generator of high power (above 500 kW) having an exterior rotor and an internal stator. For testing purposes this generator has to be rotated a long ...
36 views

### Do asperity junctions break every time a machine starts to rotate?

After reading CONTROL OF MACHINES WITH FRICTION by Brian Armstrong-Helouvry, some questions rised. The main question I ask you is: Suppose two metal surfaces in relative motion first in static ...
66 views

### Will the cart steer to the left/right by itself in this design?

I'm trying to retrofit a pull cart with electric motor. So, one wheel will have an electric hub motor and it is connected to a rotating shaft to the other non-powered wheel. The driveshaft is ...
69 views

### Could radial bearings with brackets hold the weight and load of a large cart

Me and my partner are trying to build electric pull carts to assist elderly Korean women and men who collect paper boxes for a living. These boxes are sold for recycling. They work virtually at every ...
61 views

### How to make an L7 tank gun eject with more force

I'm looking into tank autoloaders, and something that eludes me is how modern tank guns eject. I know there is a pair of "ears" that push against the case rim, but the precise mechanism ...
47 views

### Strain energy, Conservative force and Potential energy

What I know: In general, the work done by a conservative force $F$ is equal to the negative change in a potential energy. $$\int_1 ^2F.ds = - (U_2 - U_1)$$ A potential energy is always associated ...
29 views

### Can the Dynosheet be read as a Fourier transform of some sorts?

I've done some quick google search on dynosheet, and what it does is that it measures the power output of the car with respect to its frequency. My initial understanding of the dynosheet is that it ...
37 views

### Velocity of blocks under different situations

Height of all blocks is 100m. CASE 1: Blocks are at a distance of 100m in height. When they reach the ground , velocity of 1st block must be higher than velocity of second block due to the extra ...
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42 views

### Best way to deploy a projector screen from the bottom?

I want to design a system for an electronically deployable projector screen, where when not in use the screen is stored at the bottom and there are no structural elements sticking up significantly, ...
62 views

### How to create a friction-based cable exercise machine?

What would be the best mechanism to create a friction based cable machine? The point of this machine to only have resistance to movement not when the cable's stationary and without the momentum of ...
1 vote
17 views

### Replicate loft-based object to value-driven object

I've made the following oddity in Solidworks: All the dimensions are known except for the top part. This is probably because this was done using the Lofted Boss/Base feature. The Loft profile goes (...
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### In the Rankine Cycle, how does the condenser work without changing the temperature or pressure of the fluid?

The condenser changes the state of the fluid from a saturated mixture to a saturated liquid by rejecting heat, yet the process occurs isothermally and isobarically. How then does it manage to perform ...
17 views

### 3D printed titanium durability/material quality concerns

What is the material strength of titanium 3D printed parts....compared to cast or machined parts? also how do they bond the individual pieces?
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### Working of planetary gear set in electric bicycle

For mid-drive electric bicycles where the motor is attached to the pedals, it provides helping torque which reduces the force that needs to be provided on the pedal. So, how does a planetary gear set ...