Recent content by tricha122

Hi, I’m using some CAD software trying to automate some surface identification, and I’m looking to find a way to identify whether a surface is a cone. I will have access to vertices and normals at discrete points on the surface, but it will be expected that the number of these points will be...

https://goo.gl/images/ZBfE4J In a whirl frequency plot, it is always the case that forward whirl modes trend upward with rotor speed, and backward whirl modes trend downward. This is due to the gyroscopic effect. At zero speed these modes coincide / are the same. But at high speed, if there’s...

hi, I’m trying to understand why in a rotor bearing system that the critical speeds of the rotor are higher for forward whirl, and lower for backward whirl. My general understanding is that forward and backward whirl frequencies diverge due to gyroscopic effects, and for forward whirl the...

The driving forces are transformed as a result of the equations of motion being transformed. The reference below [Linear and Nonlinear Rotordynamic by Ishida & Yamamoto] shows the equations of motion - they are the same as mine with the exception that i added damping terms to the inertial frame...

Hi, I am trying to gain insight into using stationary vs. rotating coordinate frames for natural frequency calculations. I have seen many FE codes suggest that critical frequencies can be calculated differently in rotating and inertial frames, so i wanted to do a 1D calc to see for myself how...

Hi, Im wondering if / how commercial FEA codes take into account additional unbalance forces due to the off-axis displacement of masses. For instance, if I am modeling a jeffcott rotor with an unbalance, I would traditionally represent this unbalance with a force that increases with speed^2...

It is the same if you iterate the centroid and maintain the orientation (which I would say is similar to generating a full set of cylinders and relocating them) - but easier for me to process in my head. It still doesn't address the endpoint issue.

Yes I guess you can say that, keeping in mind ill be generating hundreds of cylinders one at a time and ensuring the new cylinder doesn't intersect with any existing cylinders

This is a theoretical study, and I will be biasing the orientation of the fibers using statistical functions, however the Crux of the problem I have is the condition for rejecting intersecting fibers. If I treat them as line segments, I can reject fibers that come within twice the radius of each...

Hi all, Im trying to think of a way of generating non-intersecting randomly oriented cylinders within a unit cell volume for micromechanical analysis. Several research papers suggest a monte-carlo approach was used by displacing cylinders by vectors until the "condition was satisfied" -...

I have since updated my analysis by assuming the deflection at the bolt is equivalent to the bolt reaction divided by the bolt stiffness, kb. I have attached all of my equations. I am getting Rb = 43 and Rc = 13 , (with applied load of T = 30) in my beam analysis. Modeling the beam in...

Hi all, I am trying to find the slope of a T-stub joint at the bolt in order to find the bending stress of the bolt. I have drawn 1/2 of the T-stub as a beam. The beam analysis requires (for physicality) that the slope at each side of the beam to be zero. There is an applied load, a bolt...

I am taking a micromechanics course, which lists knowledge of continuum mechanics as a prerequisite

Further, Cab = xi,a*xi,b = F^t * F confusing me even further suggesting that xi,a xi,b are the transpose of each other when a=b.

Thank you for your response. However, I still am trying to wrap my head around the introduction of a new variable. After substiuting out dXa, (dx)^2 - (dX)^2 = (xi,a*xi,a - 1)*dXa*dXa how does the kronecker delta substitute (dijej = ei) in here to get the next equation? (dx^2) -...