Recent content by Su Solberg

Hi guys, I wonder whether we can roughly estimate the energy used to buckle a hollow tube (by calculation)? I was asked to calculate the backstay of a cane to ensure it can stand for the rebound force due to abnormal operation. Thanks in advance.

Sorry, attachment missing. The following is the method of calculation in Steel Design. Assuming principle axis is unknown. find the principle axis by try and error in the equation of Sum of Torque by Tension +bearing = moment encounter in the connection group.

Hi, everyone. I was told that when a beam is short, L<=5H, the equation of "Stres=Moment*/2nd moment of initeria" is not valid (how). (where H = deapth of beam ; L is the location of F acting on that beam) Is that ture and is that relate to principle axis? Also if it is ture, why...

Thanks a lot. I wonder which manufacturer, the pump or motor. Is the equation is "start up current" = "normal current" * [Normal V / Start up V]? Also, I wonder is there any method to know how to calculate the current theoritically without perform a test? p.s. is that include as a...

Hi Guys, I have a problem about the starting current of a pump's electrical motor. I have the working condition of the pump (torque, power, speed, P and Q) But how could I calculate the start up current of an IEC standard motor? Seems I has to gather a Torque-speed curve from the...

Haha, I found the correct name of this kind of sensor. It's "Inductive proximity sensor" which can be find out easly in RS. I found this in "Industrial Motor Contorl 5th edition , Stephen L.Herman" It's really a nice electrical book to mechanical engineer.:!)

Hi guys, I am working on a Automation project and I am wondering whether there is any probe that can emit signal to a standard PLC when iron rod is found inside a concrete wall. Personally, I hope it can be avaliable from RS. Thanks for your kind help in advence.

Thanks for your Reply. The spring is used in a Shale Shaker. Since the vibration direction is 45deg to the ground level, I am curious about the spring constant K' in transverse direction. I am wonder whether there is any literature about it. P.s. Small amplitude only compares to the...

Hello All, Again, a funny question is raised: From the following site, I can determine the spring constant K for a compression spring at vertical axis. http://www.roymech.co.uk/Useful_Tables/Springs/Springs_helical.html However, I wonder is there any equation to find the spring constant...

What's Eot??

Yes, only the frictional constant F relates to viscosity and density. However, since my pipeline is a bit short, just 7m with numbers of fitting, so the only loss is K, minor loss coefficient. I am curious whether I can estimate the head when system is feeded with slurry by the clear water...

Usually, we will ask for Mass flow rate instead of velocity (FAD, Free Air Delivery = volume of air comes out at 1 atm environment). Think about turbulence and compressibility of air after the nozzle. using pito tube to obtain the speed of air after the nozzle is completely meaningless. the...

Hi Guys, I have a problem about the loss coefficient. Head loss = K * (v^2/2g) Where K is the loss coefficients. This equation is base on Darcy-Weisbach equation. I wonder how is K varies for same flow rate, same device with a different viscosity and density. Thanks a lots in...

Pump flow rate can be obtained by following engineering device: 1. for low flow, electronic meter with a propeller will help you; cheapest flow meter. 2. for high flow, pressure diffential device is a mechanical choice. 3. eddy current flow meter, easy to use, no skill is need but very expensive.

For Q1. It's easy. A. pressure from the water due to gravity = maximum 0.2bar. B. pressure of atmosphere at the tank out side. = 1 bar (anywhere of the tank surface; simplified as 1 bar as 1 ATM = 1.01XXX and varies with temp + altitude). Thinking a vacuum hot bottle, using vacuum to...