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Hello, I am converting a ~300cc single cylinder air-cooled engine to EFI. When running at around 3000RPM with a light load on it, the leanest the engine will sustain a stable air fuel ratio is around 13.5 +-0.5 variation. If I reduce the fueling even just slightly (a few percent less), the AFR...

One of the fuel injectors in my car developed a leak on the inside valve. This got me thinking - why is the needle seal metal-to-metal? With the different types of fuel resistant polymers and elastomers out there today (ex. PTFE, PFA, Delrin, Viton rubber) , wouldn't it be more reliable and less...

Is it possible to get a rough idea of position or velocity without some type of position sensor from a solenoid actuator? I am thinking that solenoid actuators are usually designed so that the inductance of the solenoid increases as the armature moves when the solenoid is turned on. Could this...

We are planning to preload a spring past its yield strength, but before its ultimate tensile strength. The spring will then be used in service for 10^7 cycles, but with a small amplitude. The amplitude stress is about 30% of its endurance strength. Even though the spring has a permanent...

Hi, We want to implement a ball check valve for a small water piston pump with a service life of 50 million cycles. Is this feasible? What kind of materials and operating conditions are conducive to a long life? From what I understand, valve failure comes from uneven wear of the ball and seat...

Hi, I am trying to understand and figure out what is the best way to control the motion of a voice coil motor using current control. I am using a "hysteresis mode" feedback seen here: http://www.cs.uiowa.edu/~jones/step/currentf/10.gif First of all, why is hysteresis even needed? Is it because...

I have a LDPE part that is subjected to a periodic compressive stress varying between about 20% of its yield strength and 0. When the machine is not running, it is subjected to a constant compressive stress of about 1% of its yield. Is it reasonable to expect this part to have no permanent set...

Hi, I have a pipe that divides into more than one non-identical branch. I am interested in solving the pressure and flow rate inside each of the branch. Thanks

Hi all, I'm trying to design a voice coil motor and was wondering if there are any good books out there to help? The force is pretty easy to obtain using Lorentz equation, but I'm not sure if I'm getting the correct values for inductance and back-EMF. Thanks

Hi all, I am trying to compute the stress and strain of a transversely loaded beam as pictured. I have seen analytical solutions for radial or tangential loading, but can't find anything for transverse loads. The boundary conditions are that the base is fixed and the slope at the end is zero. Thanks

Hi, I am wondering how linear a real helical compression spring is? Assuming the ends are ground flat, there is some preload, and the coils are not touching, how constant will be the spring rate? Are we talking less than 0.5%? Less than 1%? Less than 5%?

Hi, I am debating using voice coil as a linear actuator for a design, and I am trying to get an idea of their cost. It seems like the are much more costly than solenoids, which have essentially the same components minus the permanent magnet. Any idea for why this is? Thanks

Hi, Is it possible to perform two-way transient FSI in ANSYS? In the "getting started in workbench" guide it mentions that they have templates to do two-way fluid - static structural interaction, but nothing on transient. I want to model the transient response of a fluid, which exerts a force on...

Hi All, I'm trying to drive a piezo ultrasonic transducer with a capacitance of 1.6nF with an LC circuit. Here is the circuit diagram: http://min.us/icWNq4.jpg The square function is at 60kHz. The Inductor I made myself by winding 20AWG enamel-coated wire around a 0.44in diameter x 0.75inch...

Hi all, I am trying to use a fixed 2.7V voltage regulator (MIC5219-2.7YM5), and the voltage output is 1.4V when I wire it according to the datasheet and supply it with anywhere from 2.5V to more than 5V. When I tried putting a load on it (20K), the voltage drops to almost zero. Any idea why this...

I have a setup where a high velocity ball is directed towards a metal plate, which has an accelerometer mounted to the other side. When the ball collides with the plate (assume elastic deformation), there is a large oscillation observed in the signal from the accelerometer, which eventually...

Hi, Is there a guideline for the minimum coefficient of speed fluctuation for flywheels, below which the engine will not idle? I think this might depend on the type of engine, so assume it's a 4-stroke spark ignition engine with a very high compression ratio.

Hi, Just wondering why OHC with roller followers need lubrication, if it's rolling contact everywhere? In theory, if we remove the valve guides from the equation, does an engine with OHC roller followers even need to have the top lubricated?

Hi, I am designing and making an engine and as such several parts need to be hardened to reduce wear and increase strength. I don't have the capabilities to grind after heat-treating. One way I want to get around this is to use 17-4 PH aged to H900 (482 deg C for 1 hr). My questions are as...

Hi, I am looking for a software to visually simulate a simple dynamic mechanical system consisting of a series of pulleys, springs, and masses. By visually simulate, I mean I want to be able to place pulleys, ropes, springs, and masses as I want them, and set an initial condition or create a...