PSI - Issue 66

0LORVODY .HSND -U et al. / Procedia Structural Integrity 66 (2024) 135–141 Miloslav Kepka Jr. et al / Structural Integrity Procedia 00 (2025) 000 – 000

138

4

It was already possible to state the following conclusions: • the manufacturing company has already learned to use HFMI; • HFMI improved the fatigue strength of the tested weldments. Some differences from IIW recommendations were observed (e.g. slopes of S-N curves), these will be further evaluated and consulted with the authors of the IIW recommendations. 3. Research in cooperation with the Faculty of Civil Engineering of the Czech Technical University in Prague This research focused on thick sheet metal welds. The effect of HFMI on repair welds was also investigated. 6 so called "new" test samples with a thickness of 90 mm made of structural steel S355NL were tested by four-point bending. Photos of the test stand, parameters and results of fatigue tests of samples without HFMI application (As welded) and with HFMI application are part of Fig. 6. 10 test samples with a thickness of 80 mm were tested by four-point bending. The stress range was less than 130 MPa this time, and approximately 1,100,000 load cycles were applied to all samples. Fatigue cracks were detected in 6 test samples. This was an opportunity to deal with the fatigue life of repair welds in RTI. Photographs of the weld repair process, parameters and fatigue test results of samples with repair welds without HFMI application and with HFMI application are part of Fig. 7. In this case, too, it was possible to state partial conclusions:

• the effectiveness of HFMI was also confirmed on welded joints of large sheet metal thicknesses; • fatigue life increased more than 3 times for the examined test samples.

dŽƚĂů ŽĨ ϲ ƐĂŵƉůĞƐ ǁŝƚŚ ĚŝŵĞŶƐŝŽŶƐ ŽĨ ϳϬϬ dž ϭϬϬ dž ϵϬ ŵŵ &ĂƚŝŐƵĞ ƚĞƐƚ ǁŝƚŚ ϰͲƉŽŝŶƚ ďĞŶĚŝŶŐ͖ ^ƚƌĞƐƐ ƌĂŶŐĞ ϭϯϬ DWĂ ;Z с Ϭ͘ ϭͿ

WĂƌĞŶƚ ŵĂƚĞƌŝĂů͗ ^ϯϱϱE> ƐƚƌƵĐƚƵƌĂů ƐƚĞĞů tĞůĚŝŶŐ͗ sͲǁĞůĚ ǁŝƚŚ ĐĞƌĂŵŝĐ ďĂĐŬŝŶŐ DĞƚŚŽĚƐ͗ Ͳ ϭϯϱ ;ƌŽŽƚ ǁĞůĚͿ Ͳ ϭϮϭ ;ĨŝůůĞƌ н ĐŽǀĞƌ ůĂLJĞƌͿ &ŝůůĞƌ ŵĂƚĞƌŝĂůƐ͗ 'ϯ^ŝϭ ;ϭϯϱͿ ĂŶĚ DͲϭϮн^Ͳϳϭϳ ;ϭϮϭͿ dĞŵƉĞƌĂƚƵƌĞ ĐŽŶƚƌŽů͗ WƌĞŚĞĂƚŝŶŐ͗ ϴϬ Ͳ ϭϮϬ /ŶƚĞƌƉĂƐƐ ƚĞŵƉĞƌĂƚƵƌĞ͗ ф ϮϮϱ

ƐǁĞůĚĞĚ

,&D/

ϲϲϯϬϲϴ ϱϬϳϲϱϱ ϲϬϭϭϱϲ

ϮϮϴϬϰϭϳ Ϯϭϳϰϲϭϴ ϭϴϬϯϵϱϭ

Fig. 6. Photo of the test and results of fatigue tests.