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  1. SC83

    Reaction forces of a table

    All, I need to check if a table with a motor mounted on top of it will stand still or not under a rotational torque, i.e. starting torque of the motor. I added a top view of the square table with 4 legs (black). The rotation axis of the motor is indicated with a blue dot and is not in the...
  2. SC83

    Inertia of SCARA robot

    I want to calculate the inertia of a SCARA robot. The arms/end effector move only in the XY-plane by rotating its 3 arms. How do I calculate the total inertia around the Z-axis? I_arm_1_Z = I_arm_1_COG + m1.r1^2 I_arm_2_Z = I_arm_1_COG + m2.r2^2 I_arm_3_Z = I_arm_3_COG + m3.r3^2 I...
  3. SC83

    Reaction forces of moving SCARA robot

    Yes, the robot is fixed to a base plate which is mounted to the table frame. The 4 legs cannot be bolted in the floor.
  4. SC83

    Reaction forces of moving SCARA robot

    Hi ThomasH, Yes, the three arms move only in the XY-plane by rotation of the arms around theta 1, theta 2, theta 3. The gravitational force is in the negative Z-direction. I have defined the mass of each arm in its COG wrt the XYZ-cordinate system (indicated by the blue dots below) using point...
  5. SC83

    Reaction forces of moving SCARA robot

    Hi rb1957, Why should I forget about the table? If the inertia of the robot arm is too large then the table could move/dance on the floor as it is not bolted to the floor. I check also the load on the interface between the table and the robot in Ansys. The COG of the three arms together will...
  6. SC83

    Reaction forces of moving SCARA robot

    Dear, I have to design a table for a SCARA robot which will be mounted on top of this table. I'm not allowed to bolt the table (consisting of 4 legs bosch frame and aluminium top plate) on the ground (drilling of holes in the ground is not allowed). I need to know if the table will stand still...
  7. SC83

    Heat flow through composite wall with varying cross-sectional area

    Hi, I have a composite wall of two layers of materials A and B tightly fitted to one another. The cross-sectional area of A and B are not equal. Questions: - is the conduction Q through material A and B equal? If so, then the heat flux (Q/cross-sectional area) through material A and B are not...
  8. SC83

    Heat conduction with variable conductivity

    I want to reduce the heat conduction through a steel rod by locally reducing the cross-section of the steel rod. However, it seems that the conduction through the rod is not dependent on the position of the reduced cross-section (i.e. near the hot or cold surface). I'm trying to explain this...
  9. SC83

    State space model of mass spring damper with base excitation

    Thank you!
  10. SC83

    State space model of mass spring damper with base excitation

    Hi xnuke, Thank you for your reply. So my B matrix is: [0; 1/m] And u is: bWY cos (Wt) + kY sin (Wt) If xdot is: [x'; x''] Right? Steven
  11. SC83

    State space model of mass spring damper with base excitation

    Hi IRstuff, Thank you for the link. This is almost what I'm looking for (slide 52). However, I'm struggling to write the harmonic forcing functions (2.63) in state-space format (B matrix). Analytical, they do a superposition of the two individual particular solutions. Have you an idea of how...
  12. SC83

    State space model of mass spring damper with base excitation

    Dear, I want to make a state space model of a simple mass spring damper system with a base excitation as shown in the figure below. The equation of motion is: mx'' + bx' + kx = ky + by' How can I write this in state space (A,B,C,D) format? I have difficulties with finding the B matrix. y(t)...
  13. SC83

    Parallel leaf springs

    All, I'm designing a construction with 2 leaf springs in parallel. I have found the formulas to calculate the lateral stiffness of the leaf springs on following website: https://www.janssenprecisionengineering.com/page/flexure-guiding-2-leaf-springs-in-parallel/ However, in my case, both leaf...
  14. SC83

    Lateral stiffness of a spring

    Ok, thanks for the tips. I will take a look at it.
  15. SC83

    Vacuum force

    Ok, that's the answer I was looking for ;-) Can you maybe explain why the bottom plate does nothing in this case and why it does when it was vertical?
  16. SC83

    Lateral stiffness of a spring

    Hi, Is there a simple formula to calculate the lateral stiffness of a compression spring when both ends stay in parallel (see figure in attachment)?
  17. SC83

    Vacuum force

    Hi IRstuff, I know how to calculate a spring force. That is not what I'm looking for. I want to know what the total external force (atmospheric pressure) is that is acting on the springs, irregardless of the spring constant, seal properties etc. Is this 1 bar x the top surface or 1 bar x (top...
  18. SC83

    Vacuum force

    Hi Greg, I hoped I was still a student ;-) Ok, let’s put it differently. I doubt if it is one (only over the top plate) or two times (over the bottom and top plate) the pressure drop of 1 bar force that acts on the springs. Thus 100 kN or 200 kN.
  19. SC83

    Vacuum force

    Hi, I have a bottom plate resting on a table (see figure in attachment). On top of this bottom plate is are series of springs and on top of it rests a top plate. Between the bottom and top plate (inside the springs) is a seal to create a vacuum chamber. Question: what is the total vacuum force...
  20. SC83

    Calculate temperature rise from turning a screw spindle in a nut

    Hi, Does someone know how I can calculate the temperature rise from turning a screw spindle in a nut (thus no ball screw)? The spindle is of stainless steel, the nut of brass. I don't use any lubrication. Thanks.

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