Richard wrote:Andres: Ripples from lateral loads and rutting from lorry loads both depend o shear deformation of the wearing course.
Agree on this
Richard wrote: In both cases the asphalt is squeezed into a deformed shape.
But a very different way Richard
With a vertical load from a truck, asphalt is compressed, and transmit that load to the lower layer (base), and this to the lower one (subbase), and this to the lower one (soil), so it doesn´t matter if that load have been distributed through all those layers, if the soil is soft because of the rain, it will descend making all the layers descend causing a bump. So in this case the ahphalt is resisting nothing but a compression, wich actuallly doesn´t cause huge deformations, it´s the soil what is deformed and all the layer over it collapse and descend with the soil causing the bump
But with hoirzonal loads from brakings, the load is not transmitteed anyway, it´s the asphalt itself what must resist that load or it will do the same as if you brake over a carpet, bend and/or break. That´s the short term, but the long term will also have consequences, deformation/corrugation, or creation of bumps. Asphalt is a bit elastic, this means it´s moved on each braking, really little movement so it´s not visible, but with the long term those movements cause corrugations and bumps
Richard wrote:That deformation is dependent on the size of the load as well as the number of loadings. Ciro and I are saying it is not a problem for the sort of loading we see in F1, the numbers are smaller than highway loading.
No, they´re much higher. The vertical loads are much lower as you two have perfectly explained, but the horizontal ones are much higher because of the higher braking power of racing vehicles. Vertical loads are distributted to the soil thanks to the base and subbase, but horizontal loads, even if they´re lower than vertical ones, are not transmitted, it´s a shear stress asphalt must take. And it´s asphalt cohesion what must be enough to resist this stress.
Imagine a road with no resin at all, just gravel. A truck can pass over it perfectly (as we do on buildings to avoid mud), but if a bike apply full brakes, it will drag the gravel. Much lower load than the truck, but it´s much more difficult for the road to resist that horizontal load than the vertical one. Same with asphalt
As real world experience show:
rscsr wrote:I've heard Alex Wurz say every year that the bumps in the breaking zones (especially in China) are increasing every year due to the hard decelarations.
I´ve also heard that on spanish broadcasting, don´t know if it was DeLa Rosa or Gene, but I´ve heard it. I remind I instantly though about those bumps on MX tracks, I had never thought that could happen on asphalt tracks, and that comment made me think about this for a good part of the race
As you probably know, I love analysis, and if it´s something I´ve seen and suffered myself on real world (MX bumps) and also see it on F1 races, I can do it for hours
If I´m able to explain it in english is a different matter
but a challenge too, and I also love challenges