monique.hubrechtsgm Posted March 31, 2017 Share Posted March 31, 2017 ABS it self is quite brittle at ambient temperature and much more at low temperature. And therefore critical to stress rupture. You can have stress concentration which can take 3-4 years to appears as a crack. The patch work looks very sensible but still on a large one piece panel under under considerable driving force working as a spoiler. And on one side weak fitted. My former chausson was full of minor visual cracks. But they did not propagate. ABS cracks are very difficult to repair at that thickness. And for sure you have to do some non destructive testing of your repair on the panel. Your repair may have create a new stress point. Seeing the value of your motor home chausson welcome of which are some in our group hopefully it works out fine whit your repair. I had a slope rear hit on my rear bumper corner for about the same price repairable or replacement but the working hours on patch repair are high. But Mick if you succeed in this, hat off. Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted March 31, 2017 Share Posted March 31, 2017 Some high lights on brittleness of materials. The test still used today is the charpy test. It was a french governmental military who find out that his canon shoot material explode at low temperature. From him we learned that our bridges and gas pipelines and cranes are safe at low temperature. That material is stress relieved. His test piece is a 10 mm square piece of metal whit a v-notch of 2mm and a break test at low temp. Link to comment Share on other sites More sharing options...
Will86 Posted April 1, 2017 Share Posted April 1, 2017 Mick And yet another application at preventing cracking which you may like to consider before replacing the panel is to 'draw-file' the material edge for its full length along the side where the crack started, a practice we carried out in the aircraft industry where known stresses were likely to occur. To those not familiar with the 'draw-file' process, its a method by which a file or similar tool (held two-handed like a spoke shave) is used to smooth a materials' edge in a longitudinal direction as opposed to cross-ways. Other posters who have mentioned cracking may find on close examination that cross-cut flaws at the material edges are the cause of their cracking panels. To support Brian's post about riveting being the cause of the cracking, this was identified as the reason for the De Havilland Comet air disaster in 1954 and ... as Monique recently pointed out "ABS itself is quite brittle at ambient temperature and much more at low temperature. And therefore critical to stress rupture" On the future of plastic panelled Motorhome's that are constantly under stress by normal daily use, it does appear that most will develop cracks. Will Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted April 3, 2017 Share Posted April 3, 2017 Returned again from a sunny dog festival last week end i checked three semi integrals on fiat. Micks panel which covers the area between fiat and habitation.Some flex is there and must be there. A long standing panel who follows the fiat door and blends out towards the side wall. A recent chausson had two top metal rivets on even a smaller tongue just 1 cm apart. Rapido and adria where stress free using screws whit the classic closing dots washer and the one time press in washer seeing everywhere in your motor home from the outside. On the side towards the wall plastic nylon rivets were used. Link to comment Share on other sites More sharing options...
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