# Questions tagged [applied-mechanics]

Questions about using applied mechanics to model engineering problems.

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### Why do we use simple bending equation when bending moment is caused due to shear force?

Simple bending equation is derived assuming pure bending(when a couple is applied onto a beam with no shear stress).We tend to use the above derived equation when moment is caused due to shear stress?...
196 views

### Reynolds transport theorem and eulerian material derivative

The problem as well as my work so far are in the image. I begin with equation (2.23) and use the divergence theorem to express the second term as the surface integral part of the problem equation. ...
52 views

### What should be the density of a compressed gas while measuring the flow rate using Rotameter?

Say we have a required mass flow rate, in order to have equivalent volume flow rate, we need to consider density of the operating fluid (compressible fluid). To measure the volume flow rate in LPM, ...
289 views

### Eulerian and Lagrangian descriptions of velocity

I feel as if I understand the conceptual difference between Lagrangian and Eulerian descriptions. But I can't seem to follow the math. I have one example that I would greatly appreciate an explanation ...
62 views

### Polyurethane mix-on-the-spot system

3d printing is a slow process and for my solution I need fast printing. So I print with no infill and I fill inside with a two part, 10 min drying polyurethane resin. I mix them in a disposable cup ...
289 views

### How to calculate bearing loads in a two stage helical gear box?

Here P, Q, R, S are the bearings and G1, G2, G3, G4 are four helical gears. The gear forces tangential(Kp), Axial(Ka), Radial(Kn) are known. All the distances are known. The forces acting on bearing ...
221 views

### Thin walled pressure vessel

What is the NORMAL STRESS in a thin walled pressure vessel? I am aware of only 2 types of stresses in thin walled pressure vessels: Longitudinal & Tangential. Is any one of these 2 is ...
220 views

### LS DYNA Material Model 163, Modified Crushable Foam

Question is on the meaning of input variable TID within material model 163 of LS-Dyna 971. Definition of TID variable. TID: Table ID defining yield stress versus volumetric strain at different ...
1k views

### What components are needed to reverse the direction of a belt conveyor using one reversible motor, and how do they change the tension on the belt?

On regular conveyor belts, motors are usually placed on the head shaft where material is discharged, and tension is highest at the entrance of this head shaft. However, if the motor were to be simply ...
218 views

### Calculate the torque needed to turn a rod it's own axis [closed]

If a rod is turned around it's own axis, force/torque is needed. Let's assume the rod it self has a diameter $d$, a length $l$, the mass $m$ and should be turned by a motor on one side. The other ...
121 views

### Adding a lubricant to an already lubricious material, how is CoF affected?

I have a dry film moly-graphite lubricant (CoF=.075) and a lubricious CVD coating (CoF=.05). The CoF of each of these lubricious materials was determined using the same ASME standardized test. The ...
76 views

### Shaft Size design / replacement

does anyone have any idea what standard shaft size / adapter this is? the motor is NEMA 56C and the socket size it self is 27.8 mm in diameter and 32 overall with the key.
66 views

### Analytic expressions of the kinetic and potential energy [closed]

A homogeneous rigid circular disc (radius R, mass ms, center point S) rolls without a slip on a plain with a small angle of inclination alpha against the horizontal. A point mass MG is fixed on the ...
10k views

### How to simulate the contact between two distant parts in Ansys workbench？

I made a test in Ansys but the result doesn't seem to be the final steady state. The two bodies didn't touch each other. How can I get the right result?
414 views

### Do outer fillets|chamfers also reduce stress as inner ones do?

I kind of have an intuition or at least imagination about how fillet|chamfer of inner edges|vertexes reduce stress (concentration). But does that apply to outer edges|vertexes aswell? Maybe to a ...
981 views

### Calculating the torque requirements of the motor for a specific case

I want to use a DC 12/24V motor to rotate an assembly of glass tubes(image attached) through a hollow shaft of 25mm OD and 22mm ID, the shaft is supported on bearings on both the sides(assume minimum ...
52 views

### Structural mechanics

Ques: I have a question regarding solid mechanics and plate theory,is 2 layer plate means laminated plate or simply refers to as a plate?
517 views

### What is the maximum deflection and bending moment of a hinged hinged beam? [closed]

It is not a simply supported beam with one end hinged the other end with roller support. I am working on both the ends hinged beam. i.e at the two ends only rotation about z axis is allowed and all ...
293 views

### Applications of simple spring harmonic oscillator

For pedagogic reasons I am looking for applications in engineering for the simple spring harmonic oscillator, i.e. something like this ("harmonic" implies in particular "without damping"): . The ...
23 views

### A sealed ball is not connected to anything externally, but can have any complex mechanism inside. Can the mass change? [closed]

A sealed ball is not connected to anything externally, but can have any complex mechanism inside (mechanical, chemical, or any other). Can a wireless trigger from a remote or any other wireless ...
100 views

### Cantilever beam with disc at end (structural mechanics)

I am trying to figure out how I can assemble multiple finite elements to obtain the system mass matrix $\boldsymbol{M}$ and the stiffness matrix $\boldsymbol{K}$. The situation is depicted in a ...
80 views

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### How much torque will I need to pull a 2250Kg load?

I need to use this to find a motor that will be able to pull at most 2250 kg at a 1.5 m/s pace. At peak acceleration, I would like this to accelerate at 0.5 m/s2. The area that the load ...
86 views

### does payload weight distribution affect rolling resistance?

Recently came across the following 2-minute YouTube video that claims A Balanced Rig Saves Fuel While nicely done, it is a marketing video. Does anyone know of any unbiased studies that support the ...
363 views

### Pivot joint of pendulum with no yaw

I have a conceptual design that I've been evaluating which can be summarized as a simple pendulum extended to 3D (i.e. swing not limited to x-z plane). If I want to actually build the conceptual ...
100 views

### How to make a clamp for this motor to move it in two directions?

I'm working on a disc brake balancing machine, as shown below this is a belt pulley drive and for alignment purposes I want motor to be able to move vertically as well as inwards outwards (to tighten ...
19k views

### How can I calculate the force required to bend a 10 mm thick plate in a rolling machine?

We have a rolling machine with 3 rollers; the bottom has two rollers with diameters of 168 mm and one top roller with a diameter of 219 mm. I want to calculate the required force to bend a 10 mm ...
62 views

### What kind of positioning holding Hinges do Laptops & Notebook Computers use?

What kind of positioning holding Hinges do Laptops & Notebook Computers use? Is there a set of Mech/ Engineering terms for hinges similar to these and are there a category of them that I can ...
31 views

### vibrate a floating microbody [duplicate]

I have a tiny plastic disc of dia 1cm submerged inside water in a container in the halfway. I have to make the disc to oscillate sinusoidal with a frequency(1Hz to 10Hz) and amplitude (1 cm to 5 cm). ...
45 views

### Standard bicycle monorail design considerations

I have been thinking of a design for a standard bicycle monorail. I don't have the resources to prototype it right now so I would like to bounce the design off the community. Basically thinking of a ...
43 views

### Is it possible to use a vehicles own carbon emissions to shield it from wind drag?

Let's say a cargo ship uses a large amount of fuel while on a voyage. Could you direct the exhaust i.e. Carbon dioxide into a chamber utilising a check valve so the emissions don't backflow into the ...
1k views

### How to Calculate the Minimum Radius a Rod Can Can Be Bent Staying in the Elastic Range?

I am wondering if there is a formula (or how to derive one) for calculating the minimum radius a rod (with a given radius/diameter) can be bent around while staying in the elastic range. Obviously, ...
200 views

### Type of hinge I should use [closed]

Can you please suggest what kind (type) of hinge / pins I should use to make the mechanism in the attached file. I was considering to use the pins shown in the second image. But I am not sure if it ...
8k views

### Why are spur gear ratios not always whole numbers in practice?

Defined the Gear Ratio ($i$) as the ratio between the number of teeth on the pinion (driving gear) ($N_{1}$) and the number of teeth on the gear (driven gear) ($N_{2}$). Why is this better, if ...
59 views

### Engineering mechanics of cutting blades

There are several machines that have (rotating) cutting blades. For example the kitchen aid Vorwerk Thermomix can cut pieces of Food in hundreds of pieces within a few seconds. But why it is so? If ...
2k views

### Difference between maximum shear stress and absolute shear stress

What is the difference between maximum and absolute shear stress in multi axial stress system?
741 views

### polar moment of inertia for compound shape

I have a shape that I'd like to calculate the polar moment of inertia for: the diameter is 600mm; the hexagon in the middle sides are 70mm each; the holes around the hexagon are 130mm from the center ...
184 views

### Nonlinear simulation in ANSYS workbench

I'm trying to conduct a thermo-mechanical analysis in ansys workbench, I've been able to obtain some results using the transient thermal and static structural modules, however, I would like to perform ...
12k views

### Failure in torsion

Why does a ductile rod in torsion fail at an angle perpendicular to its axis? I know the reason for brittle material failing in pure shear but I don't understand the reason for ductile material.
1k views

### Projected area in hoop's stress structural mechanics

While calculating hoop's stress we consider projected area. Infact in bearing stress from pins in a truss something similar is applicable.Can you explain why we are taking something like this instead ...
7k views

### What is Saint Venant Principle?

I am having problem with the application of Saint Venant principle.I have heard that quite often we use that knowingly or unknowingly.I would be very greatful to anyone who would explain this very ...
2k views

### Help with a simple calculation of the required mass for a counter-weight for a horizontal hatch

Hello fellow engineers, A friend is part-way building an outside storage chest. For whatever reason, the materials and size of storage that he is going for means that the door is heavy to lift and ...
73 views

### Is there a way to construct a self-centering axle?

Suppose I have a flat plate of arbitrary but connected shape. If I try to connect an axle perpendicular to the plate it is very difficult to align it with the centre of mass, creating wobble when ...