|
|
Thread Tools | Display Modes |
#481
|
|||
|
|||
MA3 rim failure, where to now
On Fri, 10 Oct 2003, PK wrote:
Ian Smith wrote: On Thu, 9 Oct, Martin Jervis wrote: Let me explain the flaw in the logic of the standers argument by looking again at the spoke forces. Say all the spokes are stressed to a force level of 100. If we just consider a 4 spoke wheel As has been stated over and over again, considering the behaviour of wheels that aren't bicycle wheels does not necesarily give you any insight into teh behaviour of bicycle wheels. Ian, take a moment to re-read what you wrote and reflect upon it. Don't be patronmising. I know what I wrote, and it remains true. Workable bicycle wheels are but a subset of a much wider set of Wheels, considering the properties of the wider set (Yes, even Naomi's rubber band wheel) does exactly what you claim it doesn't. It gives you insight into the real physics and engineering rather than the narrow sub-set of phenomena you observe in the special case of the workable bicycle wheel. Nonsense. It gives you an insight into the bahviour of wheels that don't behave like bicycle wheels. You're welcome to think about them if you want, but the conclusions reached don't usefully translate into insights aboutthe behaviour of bicycle wheels. The question is not "how doe all wheels work", nor even "do most wheels stand or hang", it was (and is) "do bicycle wheels hang or stand on their spokes. Example, there is no _fundamental_ difference between a very elastic spoke and a real wire spoke. Indeed, and I have never claimed otherwise, but there ARE fundamentally different behavious in wheels depending upon whether you have very elastic spokes and near rigid rims or vice-versa, or some intermediate case. Similarly, there is no essential difference between a rigid rim and a real flexible rim Not of itself (assuming that be 'rigid' you mean 'near rigid'), but there is in teh behaviour of the wheel. One distributes the load evenly round the spokes, and teh other doesn't. The one that really exists in real bicycle wheel sin teh real world doesn't distribute load evenly round all teh spokes. variable rim rigidity. There is no step change threshold of rigidity at which the physics changes, it varies continuously. Indeed, and at anything approaching real bicycle wheel component rigidities, it behaves as decribed, with teh resisting action concentrated in the lower spokes. I really do think you would be wise to step back and stop defending for a moment and revisit the basic physics/engineering and look at the problem anew without delving into the esoterics of FEA, which are after all just a mathematical tool to solve difficult problems. I'm still waiting to know: 1: How you elongate your wire in teh latest 'explanation' without the tension changing. 2: Why you think the 'rigid rim' case gives you a useful insight into wheel behaviour but the 'rigid spokes' case doesn't. 3: What conclusion you got from your last bounding box thought experiment (the strange tensions / infinite acceleration one). I think you would be wise to get your basic physics right before lecturing other people on teh topic. I really am interested in teh answers to those questiosn, you know. Please do answer. regards, Ian SMith -- |\ /| no .sig |o o| |/ \| |
Ads |
#482
|
|||
|
|||
MA3 rim failure, where to now
On Fri, 10 Oct 2003, PK wrote:
Ian Smith wrote: On Thu, 9 Oct, Martin Jervis wrote: Let me explain the flaw in the logic of the standers argument by looking again at the spoke forces. Say all the spokes are stressed to a force level of 100. If we just consider a 4 spoke wheel As has been stated over and over again, considering the behaviour of wheels that aren't bicycle wheels does not necesarily give you any insight into teh behaviour of bicycle wheels. Ian, take a moment to re-read what you wrote and reflect upon it. Don't be patronmising. I know what I wrote, and it remains true. Workable bicycle wheels are but a subset of a much wider set of Wheels, considering the properties of the wider set (Yes, even Naomi's rubber band wheel) does exactly what you claim it doesn't. It gives you insight into the real physics and engineering rather than the narrow sub-set of phenomena you observe in the special case of the workable bicycle wheel. Nonsense. It gives you an insight into the bahviour of wheels that don't behave like bicycle wheels. You're welcome to think about them if you want, but the conclusions reached don't usefully translate into insights aboutthe behaviour of bicycle wheels. The question is not "how doe all wheels work", nor even "do most wheels stand or hang", it was (and is) "do bicycle wheels hang or stand on their spokes. Example, there is no _fundamental_ difference between a very elastic spoke and a real wire spoke. Indeed, and I have never claimed otherwise, but there ARE fundamentally different behavious in wheels depending upon whether you have very elastic spokes and near rigid rims or vice-versa, or some intermediate case. Similarly, there is no essential difference between a rigid rim and a real flexible rim Not of itself (assuming that be 'rigid' you mean 'near rigid'), but there is in teh behaviour of the wheel. One distributes the load evenly round the spokes, and teh other doesn't. The one that really exists in real bicycle wheel sin teh real world doesn't distribute load evenly round all teh spokes. variable rim rigidity. There is no step change threshold of rigidity at which the physics changes, it varies continuously. Indeed, and at anything approaching real bicycle wheel component rigidities, it behaves as decribed, with teh resisting action concentrated in the lower spokes. I really do think you would be wise to step back and stop defending for a moment and revisit the basic physics/engineering and look at the problem anew without delving into the esoterics of FEA, which are after all just a mathematical tool to solve difficult problems. I'm still waiting to know: 1: How you elongate your wire in teh latest 'explanation' without the tension changing. 2: Why you think the 'rigid rim' case gives you a useful insight into wheel behaviour but the 'rigid spokes' case doesn't. 3: What conclusion you got from your last bounding box thought experiment (the strange tensions / infinite acceleration one). I think you would be wise to get your basic physics right before lecturing other people on teh topic. I really am interested in teh answers to those questiosn, you know. Please do answer. regards, Ian SMith -- |\ /| no .sig |o o| |/ \| |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Tire Failure | AGRIBOB | Techniques | 13 | January 13th 04 09:46 PM |
Tyre failure example (with an aside on tyre liners) | Andrew Webster | Techniques | 16 | December 12th 03 03:59 AM |
Tyre failure and tyre liners | Andrew Webster | Techniques | 5 | December 4th 03 08:26 PM |
Rad-loc hinge failure | Paul Dalen | Recumbent Biking | 2 | August 4th 03 12:14 AM |