# All Questions

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54 views

### Should lithium batteries be recharged after every use , or when they are exhausted?

For a small unit like a drill: Is it better to charge after any use or wait until the lithium battery is exhausted ?
20 views

### Why do instructions on creation of roller chain sprocket tooth profile require redundant measurements?

I'm CADing a tooth profile for a bicycle chainring model and I'm referring my measurements and formulas to these sources: http://www.gearseds.com/files/design_draw_sprocket_5.pdf https://data.epo.org/...
44 views

### Are these force components right?

Would you also decompose the centrifugal force this way? $m_{tot}$ is the total mass of the Hyperloop. $a_c$ is the centripetal acceleration. $\beta_a$ is the angle formed by the air bearings with ...
29 views

### Constrained optimization using Lagrangian

I'm trying to optimize the weight of a truss with the constraint that the trusses don't face more stress than the material resistance. Here is a sketch of my truss: I have a Python function that ...
6 views

### Time delay in wave generation, High Density Arbitrary Waveform Generators, (Zurich Instruments)

I am trying to generate 2 waves without any phase delay using HDAWG, Arbitrary Waveform Generator(2.4 GSa/s, 16 bit), by Zurich Instruments. I have written the code in the Lab One user interface, ...
34 views

### Swash Plate Pump Design

My understanding of swash plates led me to believe that the pistons in a swash plate pump rotate around with the driving shaft along with the chambers in which they aspirate (e.g. M&S Hydraulic ...
30 views

### Does utilizing exhaust energy to supercharge (“turbocharging”) increase the thermal efficiency of a gasoline internal combustion engine?

The work done by a turbocharger increases the inlet charge without much of a burden to the exhaust flow. This increases the amount of air (and fuel) that flows into the engine. How does this affect ...
66 views

### Cooling tower for nuclear power plants

Cooling towers for nuclear power plants often have the shape of a hyperboloid. At first glance, I thought that an obvious reason for this would be the smaller sectional area, meaning the tower would ...
43 views

### How do i find the effective length factor (k) for a column from this chart?

I need to find the effective length of a column (kl) from this chart which can be found in the "design of concrete structure" By Dr. Arthur Nilson. the question states "if Psi top is 1.5 and the ...
47 views

### Operational Amplifier

In this case, can I say that $V_E$ correspond to -0.7? if yes, why can this be?
37 views

### What really is so special about principal stresses or stress invariants?

At any point inside a structural element under deformation, we can always find three planes such that when we define a coordinate system with basis vectors lying on those planes, the shear stresses at ...
37 views

### Why is tensorial shear strain half of engineering shear strain?

Small deformation shear strain $\gamma$ in engineering can be expressed as $$\gamma_{xy}=\alpha +\beta ={\frac {\partial u_{y}}{\partial x}}+{\frac {\partial u_{x}}{\partial y}}$$ where $u$ ...
38 views

### Efficiency of a planetary gearbox as a function of the lubricants viscosity

So I have a client that is asking about if they should switch from one lubricant to another in a planetary gearbox they have. The main advantage that this new lubricant has is that it has a much ...
42 views

### How to professionally mount an air duct through a core hole in limestone brickwork

We need to add ventilation holes to an existing building. The holes will be core-hole drilled through a limestone brick wall. The bricks have crevices. The contractor is acting stupid and obstructive ...
23 views

### Could I define an isothermal efficiency?

There's an adiabatic efficiency because real processes can't be adiabatic. I want an isothermal compression (yes, I know an adiabatic compression consumes less work, but my pressure differential is ...
15 views

### notch consideration

I'm designing a bevel gear. And I want to design the pinion and the shaft such as they are one piece all together. So I was wondering if I should consider a notch effect at the exact point where the ...
15 views

### Selection Of coupling and determining size of motor to rotate heavy disc

Following image is something I want to design. The uniform stainless steel round plate of diameter 1000mm and thickness 10mm is rotated by a stepper motor. But after every turn, a pressure of 3000 kg/...
33 views

### Pressure design thickness and how relates to hoop stress

Stress = Force / Area Lets see with static force... what happens to stress output when decrease the area. ...
19 views

### Looking for a suitable tensile tester

Does anyone know of tensile testers that satisfy the following conditions? Has a motor that can work in a vacuum environment Has dimensions less then 7 inch by 7 inch by 10 inch These aren't hard ...
14 views

### What is the mechanism of adsorption-desorption on biochar obtained from slow pyrolysis/ torrefaction?

Biochar is a major by-product from pyrolysis along with bio-oil and it is considered an important chemical feed-stock because of many light oxygenates. I have read some papers on using bio-char use ...
39 views

### Calculating area moment of inertia for a beam with underslung plate?

In a number of designs, a beam will have an underslung welded plate attached, as shown below: In this sketch, a symmetrical standard steel beam/column of dimensions H1 x B1, with web and flange ...
28 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 ...
47 views

### Software for automatic building floorplan calculation / drawing (packing problem)

An apartment yield analysis is a set of draft drawings in which the optimum residential apartment layout and resultant yield is calculated for a given building site, taking into account development ...
58 views

### Motors that would work in a vacuum

What are some examples of motors, preferably less than \$300, that would be able to function in a vacuum?
45 views

I am having a very difficult time identifying this thread. This part is a plug that I am trying to replace because the threads were stripped. The best fit for pitch is 11 threads per inch (imperial), ...
49 views

### What mechanism do I use for this pen-like design?

I am trying to make a pen-like product that moves out fluid from its tip for some special chores, but I am having issues about the motion of the clutch. The picture you see is a sectioned concept ...
38 views

### Rotational bending in Timoshenko beam theory

The Wikipedia article on Timoshenko beam theory says: The model takes into account shear deformation and rotational bending effects, I am familiar with shear deformation, but what is meant by "...
16 views

### Structural analysis + thermal expansion using ANSYS static module

I am attempting to model a steel sample subjected to combined mechanical and thermal loading. The thermal loading can be quite elevated, where reduction in the elastic modulus will occur. Does anyone ...
52 views

### Amount of thrust needed to Hover on the moon?

I am interested in knowing how many newton's of force is needed to keep 1 kg of mass hovering above the moon's surface. And whether the current most powerful ion thrusters would be up to the task? I ...
24 views

### How to evaluate the fuel consumption rate of an air conditioner in a vehicle?

Using two cases studies: I. When the windows are wound up and air conditioner is turned on. II. When the windows are wound down and air conditioner is turned off. Case studies are evaluated for ...
82 views

### How do I calculate the member forces of a truss when external force acts on the member (not joint)?

Given a three member truss structure shown here: How do I find the vertical and horizontal displacements at M? Assume all members are elastic and E,A, I and constant. I start with finding the ...
30 views

### Calculate Engine Oil Pressure

Hello iam curious as to how you would calculate engine oil pressure for a engine.I've noticed on my car i just got, it uses a pressure switch in the oil system to measure engine oil pressure it seems ...
27 views

### hydrostatic storage of gasses

This question is a bit general but hopefully someone can point me in the right direction. If you have a metal container, welded shut that's fitted into a hole that is say 10 meters wide and 30 meters ...
14 views

### Etabs Semi Rigid Diaphragms

In Etabs, if I model a building with semi-rigid diaphragms assigned to the floors, the floors will now transfer gravity loads when default meshing is assigned (as compared to rigid diaphragms ...
62 views

### Will electroplating a ventilated brake rotor with copper improve its cooling capacity and maximum its lifespan?

Since copper is excellent at dissipating heat and does not rust, I am surprised that brake manufacturers do not electroplate cast iron/steel brake rotors with a thin layer of copper (~.5mm). There are ...
31 views

### Why can we ignore transverse shear stress in thin beams?

In a text I'm reading on Euler-Bernoulli beam theory it is said that as the beam is assumed to be thin, the effect of transverse shear stress is ignored. If the beam is thick, we need to use ...
82 views

### I have a problem with my representation of roll in Simulink

I am currently an engineering student and a member of the aerospace club of my engineering school (ESILV) which is called LéoFly. We’re a team of 12 students and are building a Fusex (...
48 views

### When designing scissors, how do you design the blade geometry to ensure good cutting capabilities?

I have been looking online and found there should be two points of contact, one in the blades and one in the pin. In order to achieve this, I assume there's a slight angle of the blades into the ...
48 views

### What is the axis of a pipe?

Sorry, it seems like the answer to this question is just a quick google search away; but I have not found a page defining what the axis is. My guess was that the axis of a piple is the imaginary line ...
70 views

### Ackerman steering

I'm designing a steering mechanism following the Ackerman principle. I've met the condition that my steering arms' normal projections must cross in the middle of the rear axle however when I do a turn ...
26 views

### Heat Exchanger- the calculation of q

What is the heat transfer difference between parallel flow and counter-flow heat exchanger? Are different equations used to calculate q?
55 views

### Why are moulds sometimes dimensionally larger than the metal components they make?

I have this question and I can't seem to find any sources which I can used to determine a potential answer.
24 views

### The speed of induction motor in matlab is starting from synchronous speed

The speed of the induction motor is starting from around synchronous speed. The speed should start from zero. What is the reason behind that?
21 views

### Is a starter relay needed to supply the current to the starter motor solenoid?

Considering the fact that the starter solenoid needs a maximum of 50 Amps initially (in order for the pinion gear to engage to the flywheel through the plunger and lever) and then some 8 Amps during ...
32 views

### (CAD) Inventor - Extrude rectangular pattern of circle sketches

[ Hello, I try to extrude a lot of circle sketches but I can't select all of them and when I try, there is so many lags. Does someone has a solution ? I am sorry I'm a noob in CAD. Thank you so much !...
28 views

### Is starter motor running if I hold the ignition switch at the START position?

Suppose that the engine cranking has been successful but I keep holding the ignition switch at the START position instead of releasing the switch to go at the RUN position. Does this mean that the ...
4k views

### What is the purpose of building foundations?

According to many sources, one of the purposes of building's foundations is "To distribute the weight of the structure over large area so as to avoid over-loading of the soil beneath." (Wikipedia) On ...
13 views

### can submersible pumps be used for leachate from landfill that may have some solid particles of size 15-20mm?

I would like to know if submersible pumps can be used to extract leachate from leachate wells. The leachate is likely to contain solids of size 15-20mm. Further the pump should have diameter less than ...