12 Replies Latest reply on Aug 21, 2009 11:05 PM by Derek Bishop

    Hoist Drum Stress Analyis

    Poovaiah Devenira

      A.

        • Re: Hoist Drum Stress Analyis
          Derek Bishop
          You create a simulation study then press the run button. Would you like me to tell you how to design a nuclear power station next.
            • Re: Hoist Drum Stress Analyis
              Mauricio Martinez-Saez

              9972 wrote:

               

              You create a simulation study then press the run button. Would you like me to tell you how to design a nuclear power station next.

               

              What was the original question?  I only see "A"....

               

              By the way,  any one have a model with an example on how to do a non-linear analysis of a cable (wire rope), fixed between two fixed points and having a non-uniform radial load (not necessarily in one single plane) which generate axial tension on the cable which come from a membrane acting under wind loads... the idea is to simulate the stretch, which will modify the catenaries and therefore the axial tension (as the cable get longer and the catenaries described between the two fixed points will change), as well as the direction of the forces acting over the cable since the change on the catenaries will also produce a change on the membrane attached to the cable.  Something like the behabior of a cable placed on the edges of a sail having the sail under wind load.

               

              This is easier that the design of a nuclear power plant...

               

              I am doing this with another software to analyze the behavior of tension membrane structures, but I will like to try it with SW simulation, which unfortunately do not have any "cable" members... (like it have bolts, springs, etc.)  maybe can be simulate using a spring, but the problem is that the response of a wire rope cable is not linear at all.

               

              Do nay one know is this is possible to do with SW Simulation?

                • Re: Hoist Drum Stress Analyis
                  Derek Bishop

                  I was being sarcastic. The question was how do you design a hoist. Some of the people asking these questions don't seem to have a clue. I don't know how to design a nuclear power station so please don't ask!

                   

                  In regard to your questions my intuition would be to just model the cable as a steel rod with a suitable value of E. Run a case that can be easily verified by  a manual calculation. You've probably already thought of this anyhow.

                    • Re: Hoist Drum Stress Analyis
                      Poovaiah Devenira

                      Well, the question was not on How to design a hoist, It was about how to analyze a hoist, All I was looking for if anyone had done any hoist analysis before, and if there was any information regarding this in the community, before I start an analysis, I like to read about problems other people have encountered and solutions for them. So I just threw the question out to see if anyone had done hoist analysis before and run into problems, in solid Work. I did finish my Hoist Drum analysis and if you want information about it I would be glad to share it.

                      • Re: Hoist Drum Stress Analyis
                        Poovaiah Devenira

                        Well, the question was not on How to design a hoist, It was about how to analyze a hoist, All I was looking for if anyone had done any hoist analysis before, and if there was any information regarding this in the community, before I start an analysis, I like to read about problems other people have encountered and solutions for them. So I just threw the question out to see if anyone had done hoist analysis before and run into problems, in solid Work. I did finish my Hoist Drum analysis and if you want information about it I would be glad to share it.

                          • Re: Hoist Drum Stress Analyis
                            Derek Bishop
                            Good for you. Interested to hear what you found.
                              • Re: Hoist Drum Stress Analyis
                                Poovaiah Devenira
                                The Hoist Drum I analyzed was a multiple disk Hoist drum. The four Discs were attached to each other with 6 turned bolts ,1.5 in diameter & 12 in. in length . Individual wire rope is run to through each of these discs. The maximum torque experience by each of the discs is 775,000 lb-in. The bolt holes are drilled and reamed. So the assumption is made that the entire load is transferred via the bolts not taking any friction into account. I was successful in simulation the above as a linear static simulation. However when I tried to simulate it using non linear static simulation, the bolt connectors were giving me issues, I did run these issues through tech support and they are still working on it to see if they have a solution for it. The error message for non linear simulation is: Bolt Connector source surface not defined”.

                                The results from static analysis are in close agreement with the hand calculations and should be sufficient to analysis such an arrangement

                            • Re: Hoist Drum Stress Analyis
                              Mauricio Martinez-Saez

                              9972 wrote:

                               

                              I was being sarcastic. The question was how do you design a hoist. Some of the people asking these questions don't seem to have a clue. I don't know how to design a nuclear power station so please don't ask!

                               

                              In regard to your questions my intuition would be to just model the cable as a steel rod with a suitable value of E. Run a case that can be easily verified by  a manual calculation. You've probably already thought of this anyhow.


                              Derek,

                               

                              The problem with Wire Rope (steel cables), particularly the ones with a non-metallic core, is that under tension work as a mechanism, not as a material, let me explain what I mean.

                               

                              Steel spiral strand cables typically have a Young's modulus, E of 150±10 kN/mm² (or 150±10 Gpa). Spiral strand cables suffers from construction stretch, where the strands untwist and compact when the cable is loaded.  This is normally removed by pre-stretching the cable and cycling the load up and down to 45 - 50% of the ultimate tensile load until the highly non-linear response created by the "construction stretch" is removed.  However when cables are used in tension structures, this pre-stretching process is not done since the "construction stretch" is something you what to use as a "damper" on the entire structure.

                               

                              When analyzing the behavior of a cable on a crane, bridge, etc, the approach you indicate can be used since normally you are dealing with pre-stretched cables, however on what I want to model, I need to simulate with high accuracy the changes in length of the cable under load, since those changes generate changes on the geometry of the cable catenaries and therefore changes on the axial forces, as well as changes on the geometry of the membrane transferring the wind load to the cables.  The behavior of this systems is "geometrically-non-linear", and involve a "force - form finding - equilibrium' problem.   There are applications dedicated to this type of analysis (tension structures, combining industrial fabrics and cables), like Forten 3000 (which I presently use), but I will like to see if I can do the analysis of some sections with SW Simulation, so far, I do not found a valid way to do this.

                                • Re: Hoist Drum Stress Analyis
                                  Derek Bishop

                                  We use a simplified version of the catenary equation to model conveyor belt profiles. We use this for both steel reinfrced belts and pfabric reinforced belts which have even greater stretch. I fail to see why the error in ussing the catenary equation for your application is so significant. Have you ever compared the results you get from the other programs with a manual calculation without external loads. What kind of error are we talking about? I cannot see why you still cannot derive an equivalent spring modulus for the cable.

                                    • Re: Hoist Drum Stress Analyis
                                      Mauricio Martinez-Saez

                                      9972 wrote:

                                       

                                      We use a simplified version of the catenary equation to model conveyor belt profiles. We use this for both steel reinfrced belts and pfabric reinforced belts which have even greater stretch. I fail to see why the error in ussing the catenary equation for your application is so significant. Have you ever compared the results you get from the other programs with a manual calculation without external loads. What kind of error are we talking about? I cannot see why you still cannot derive an equivalent spring modulus for the cable.

                                       


                                      I have no problems using the catenary equation to model cables, used that for years to calculate electric transmission lines.  The problem with the catenary cables of a tension membrane structure is that as the elastic catenary formed by the cable change geometry (and plane) as the cable gets longer due to stretch the entire force system on the structure chages.  In fact this effect caused by the large displacements of the structure are used as a damper and must be considered on the design of the structure,  as you know tension structures utilize the "mechanics" of the cables and the membrane.  I can calculate the complete system with a numerical model and I can run the analysis with a especialized software, but since I model the structure in SW will be nice if I can su some of the analysis using simulation (not the entire structure, since due to size and to the "membrane" the analysis of a complete structure in Simulation will take for ever.

                                       

                                      For normal structures (complete large structures) I used RISA-3D, for tension structures I use FORTEN, for the details (connections, base plates, pins, tensors, etc.) I use SImulation