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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2
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71 views

Calculating the bending moment ($M$) of a beam as it relates to stress ($σ$) and strain ($ε$)?

I am trying to learn how to work out the bending moment for progressively complex systems to model a beam. I am assuming only one axis of motion (transverse = $y$). For the basic equations of motion, $...
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69 views

Calculate fan power

I was wondering how to calculate the required fan power for the following air pipe network. Other losses besides friction is not calculated for. Known parameters: Fan provided flow, VA = 3000 m3/h ...
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3answers
65 views

The behavior of the stress-strain curve of metal, containing a void

Let's assume that in a metal sample without any dislocation, there is a void. Then we conduct a uniaxial tensile test.
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0answers
60 views

Calculate required torque for cam design

Would like to check the following design (snail cam) require how much motor rated torque? To ease calculation, i have include some assumed factor as below. Two extreme condition (rotation degree) to ...
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45 views

Why funnelling air in order to increase the velocity is a bad idea when generating power

Disclaimer: I’m not trying to violate the conservation of energy here; I know that’s impossible for us mortals. I think I’m either wrong or not considering something, I just want someone to point it ...
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0answers
34 views

How does NASA's QueSST X-59 jet work?

The QueSST (Quiet Supersonic Transport) is a project to create a more diffuse sonic boom in order to use supersonic flight commercially without the usual abrupt 1~2 psf pressure spike damaging the ...
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55 views

Glass bottle with a prolonged neck that continues into the inner space

Is it possible to create following two shapes from glass using currently known glass mass production techniques? Shape #1: bottle with a prolonged neck that continues into the inner space, like this (...
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33 views

Exceed 'designed' speed ratio of timing belt

I'm trying to create a setup to transfer motion from a motor to a shaft that requires a much higher torque (bi-directional). The housing is about 6 inches long and the speed ratio needed will be ...
2
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0answers
65 views

Is having a keyway in aluminium for 30Nm a bad idea?

I'm designing an aluminium shaft hub for a 16mm keyed shaft with a maximum torque of 30Nm. However, stress analysis tells me that the keyway can suffer too much stress: If my understanding is correct,...
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17 views

ZARN bearings vs thrust tapered bearing pairs

Does anyone know how needle assemblies like this stack up against having a pair of thrust tapered bearings back to back in terms of radial and axial load? That is, a bearing like this: as opposed to ...
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0answers
71 views

How is motor torque related to capstan equation?

I know that capstan equation relates $T_{in}$ and $T_{out}$ as $T_{out} = T_{in}e^{u \cdot F_c}$, where $u$ is friction coefficient and $F_c$ is wrap (slip) angle. In my situation, the capstan is ...
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1answer
33 views

Constant crosshead speed or constant strain rate for comparing samples of differing thickness?

Say I have two different specimens of a material, one is 10mm thick and the other is 1mm thick. Assume that this material has properties which vary depending on the rate of deformation (I would call ...
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32 views

How do I calculate Pressure drop across relief valve and then force on piston?

So, I'm designing a basic downhole hydraulic tool cutter of an OD = 5 1/2 in., and my tool contains a relief valve and a piston. I am trying to calculate pressure drop across the relief valve so that ...
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30 views

When calculating a car's suspension caster, after turning the steering wheel 20 degrees, why multiply by 1.5?

To calculate caster of one side of a vehicle, the steering wheel is turned 20 degrees to the left, and the camber is obtained; this represents the 'in' value of the front right tire. Then the steering ...
2
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1answer
71 views

Generating Linear Velocity Movement?

In preparation for a Fluid Mechanics experiment, I am looking for a simple commercial ready made apparatus to generate a linear velocity trend to prove a new theory: https://aip.scitation.org/doi/abs/...
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25 views

How to measure / calculate Tait-Bryan angles of a moving platform in SimMechanics

I exported a model of the mechanism created in SolidWorks to SimMechanics in order to explore the possibilities of control. To solve the problem, i need to know the angular position of the mobile ...
2
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14 views

What's the best type of steam Trap for Superheated Steam?

Process Engineering Newbie here. What kind of Steam Traps are best suited for condensate removal in super-heated steam line or manifold? The super-heated steam is to be supplied to a process reactor ...
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0answers
37 views

Unexpected stress concentration results

I've run some stress simulations but I keep getting some unexpected results. I have 3 parts connected using 4 bolts as follows: A torque of 1N is applied to the hole on the right to simulate a hung ...
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49 views

What screw to use with 1.8mm thick countersunk brackets?

I have a few brackets that are 1.8mm thick with 4.5mm countersunk holes like this: The countersunk machine screws that I've found have head heights of at least 2.2mm (some 3.2mm). This is taken from ...
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29 views

In a nonlinear static two-step subcase, why does the load step decrease after the first step?

I am using MSC Nastran for nonlinear static analysis (sol 400). Step 1 contains a small perturbation load laterally on a thin-walled cylinder. Step 2 contains a very large compressive load. ...
2
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0answers
39 views

What is the kinetic energy required to impact the surface of asphalt roads?

I am trying to find estimates of the minimum kinetic energy required to impact the surface of asphalt roads as a first-order impact assessment of road functionality to rockfall (i.e. boulders hitting ...
2
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2answers
113 views

How to solve this linear motion problem?

Context: I have a lead screw rod, nut and a pulley aligned vertically. The nut is attached on top of the pulley so their respective bores are aligned and the rod is arranged so that it is threaded ...
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66 views

Is a Geodesic Dome (fuller dome) that floats possible? What material or engineering effort would it take?

Buckminster Fuller has popularized Geodesic Domes (invented by Dr. Walther Bauersfeld who based it on the use of convex polyhedrons), and thus, making buildings with a very large roofs that don't ...
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0answers
20 views

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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373 views

how to calculate required torque and rpm to through a 160 gram cricket ball horizontally at 160km/h velocity?

I am going to design a bowling machine. In this design, I'm going to use two motors that are being placed vertically and their shaft are attached with two horizontal identical wheels with a space of ...
2
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1answer
96 views

Center of rotation (rigid body)

I know the meaning of (instantaneous) “center of rotation” and “center of zero acceleration” for a rigid body. I know that they do not coincide (in general) and that their positions change with the ...
2
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1answer
162 views

Calculating mass flow rate of a scramjet engine?

First post here. I'm an undergraduate ME interested in fluid mechanics. I came across scramjets and I was interested about the engine. I want to calculate the mass flow rate of the engine and I made ...
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0answers
23 views

Flux Cored MIG on unknown steels, what is this stuff?

Welding on some unknown Steel, I made the weld, and this stuff formed. It looks like a fast shutter speed shot of smoke or something for me but it's a solid material that has formed. It almost seems ...
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0answers
26 views

How to find a dimension that isn't explicit if there are tolerances

For a part like the one shown, let's say I wanted to find the dimension labeled 3", if it wasn't already labeled. Since there are tolerances already on the part, how would I determine the 3" value ...
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0answers
31 views

Is there some temperature at which all “5w” oils should have about the same viscosity?

Is there some temperature at which all "5w" motor oils should have about the same viscosity? (5w-20, 5w-30, 5w-40, 5w-50, etc.) I am looking for SAE or ASTM wording or chart that says it straight ...
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0answers
26 views

Solar Heat Gain/Outside Temperature Effects on a House

I'm currently a sophomore Mechanical engineering student and need some help with an equation for my project. I am coding a simulation in Matlab and have been given a very short time frame to do it. I ...
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111 views

What is the optimal shape of a beam subject to three point bending?

Assume we have a beam with density $\rho$ that is subject to three-point bending according to the image above. The beam cross section is rectangular with the variable height $H(x)$ and constant width $...
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27 views

How to measure the inertia of an object using a motor

first time on this board even if I've been lurking for a while. I'm a tennis racquet technician and, for the sake of saving some money and just for the fun of it, I'm trying to build a machine that ...
2
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0answers
78 views

FEA using abaqus, and it does not follow the trend

I am doing finite element analysis of a donut shape for my school work. I'm increasing the thickness of the object with a 1 mm increment and run FEA each time, and then comparing the maximum ...
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0answers
111 views

Calculation of critical internal thread according to VDI 2230 Part 1

I’m doing a “Systematic calculation of highly stressed bolted joints – Joints with cylindrical bolt“ according to VDI 2230 Part 1. In step of calculation R11 “minimum length of engagement”, when my ...
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0answers
31 views

How to select the distance between two starwheeels holding a bottle?

If you have some experience in th field of packing and filling can you tell me which two areas should i choose to support the bottle with two starwheels ? I think the red area should be supported as ...
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0answers
61 views

Performance of RC car under different gear ratio, measured data vs hypothesis

Assuming the driveshaft of the rear wheeled drive RC car follows the linear DC motor theory for stall torque and no-load RPM, also voltage supplied is constant and no inductance as well. Note: the ...
2
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0answers
52 views

hot wire anemometry

Hot wire anemometry can be used to measure the temperature of a wire in fluid flow. The voltage fluctuation across the wire is used in conjunction with an energy balance on the wire to obtain the ...
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0answers
20 views

Visibility/Height Requirements for Plumbing Air-Gaps (Commercial Building)

Are there any visibility/height requirements with regards to plumbing air-gap design/installation? We're looking at using an air gap device to allow HVAC condensate drip to enter a buildings ...
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0answers
475 views

Flex and Static Bend Radius of a Cable: Which one should be larger?

I am looking for a cable to be placed in a drag chain that is moved multiple times per minute. Therefore, the cable needs to have a flex lifetime of over 1M times. Since the space is also tight, the ...
2
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0answers
68 views

What is the connection between PID and feedforward controllers?

They are tightly connected as some concepts of feedforward is based on PID algorithms, and both of them are control systems. But when I see a phrase such as "Feed forwards augment PID control", I'm ...
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0answers
147 views

Analytical shape of a pump curve

I'm looking for a formula to arrive at a pump curve for a centrifugal pump: $H(Q, n)$ - total head delivered as a function of flow and speed (rpm), and of course some pump specific parameters. I find ...
2
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0answers
55 views

Gearbox oil/grease leakage

Recently I encountered a problem of oil leakage from different driving systems SERVO gearboxes. The transmitted mechanical power ranges from 2 to 8 kW, while the motor speed (the gearbox input speed) ...
2
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0answers
41 views

About Shot blast machine

In addition to the machine parts we manufacture in our foundry we also produce high quality steel abrasive including low carbon round corn, cut wire, steel grit amongst others. We will be happy to ...
2
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1answer
323 views

press fit ball joint

I enjoy creating mechanical designs but I am not a trained mechanical engineer. I have a technical issue with a joint design that needs to be permanently retained using a press (snap) fit. Any idea ...
2
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0answers
77 views

How to join two beams rigidly?

Hi I am making a beam model using Abaqus. There are two beams created. I wanted to join two beams rigidly in the connection to transfer moments between beams. However, I do not know what connector or ...
2
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1answer
325 views

Trouble with Base circle and meshing with spur gears

I am a novice who is trying to make some gears. I have followed the formula's but sadly something seems to go wrong and the gear's don't come out right. Below is some dimensions and pictures. Gear 1 ...
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0answers
88 views

Determining the load on a pump vibration isolator

It seems to me that pump vibration isolators need to support: The weight of the pump The weight of the water in the pump The weight of the water (only) in the drop to the pump The supplier of ...
2
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0answers
129 views

How do I calculate the velocity of the piston?

I have a system with a motor connected to the trapezoidal lead screw. The lead screw is connected to the tube which is connected to the piston. The piston has to pump 1000cc oil against a pressure of ...
2
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0answers
31 views

How to apply the permeability value found from an experiment?

I have done a permeability experiment on LDPE in the presence of air using a 25mm circular specimen. At 30'C, the permeability was found to be 1.846 barrer. Now I am trying to apply this permeability ...

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