Untersuchungen zur Grenzvorspannkraft von hochfesten Schraubengarnituren

Investigations of the limit preload force of high-strength bolt and nut assemblies. In DIN EN 1090-2, the decisive specifications, for preloaded bolts a subsequent control of the assembly is specified. Among others, preloaded bolts have to be checked for overtightening. If a bolt is classified as overtightened, this can result in the entire bolt group having to be replaced. In addition to the high cost of replacement, this often means that further work has to be temporarily halted. However, there is a lack of knowledge about the degree of utilization of the bolt defined as overtightened. In order to assess the bolts with regard to overtightening, DIN EN 1090-2 gives a maximum exceeding of the specified angle of further rotation for the combined method. Experimental investigations on bolts of diameters M16 and M20 with different lengths showed that overelastic preloading forces only have a significant influence on the load-bearing behavior from the onset of necking. The evaluation of prestressed bolts with regard to overtightening, as specified in DIN EN 1090-2, seems to be too general and too conservative for the bolt diameters and lengths investigated so far. © 2022, Ernst und Sohn. All rights reserved.