Fatigue properties of arc‐welded lap joints with weld start and end points

The present paper contains a methodology for modeling and life assessment of fatigue loaded welded components providing distinct weld start and end locations. The proposed methodology follows the IIW recommendation regarding modeling and finite element meshing of weld toe and root by means of an effective notch radius and uses the corresponding Wöhler curve (FAT class) to assess the durability. Geometrical singularities and, therewith, numerical discontinuities, can be overcome especially when 3D weld root problems are treated. The fatigue life assessment is performed on the basis of normal stresses acting at the failure-critical weld toe and root locations. Comprehensive experimental database containing stress and fatigue life results derived from motor truck's hypoid rear axles providing complex 3D welds subject to vertical, longitudinal, and torsional loading is used to verify the calculation accuracy of the proposed methodology. The agreement between experimentally determined and calculated fatigue results is satisfactory.

Section: State Of the Artmentioning

confidence: 98%

Modeling and fatigue assessment of weld start‐end locations based on the effective notch stress approach

Malikoutsakis

Savaidis

2011

“…The total amount of elements of the whole weld toe with the highest scanner resolution is way over 3610 6 . Hence, the second sub model was split into four parts (a to d) in order to calculate them separately.…”

Section: Re-evaluationmentioning

confidence: 99%

“…Successful appliance regarding standard seam welds can be seen in Seeger et al [4] and Savaidis et al [5]. In fact, research concerning weld ends at thin sheet structures exist [6], but they only provide information on the resistance side. A general approach to determine the notch stresses on the loading side are still missing.…”

Section: Introductionmentioning

confidence: 98%

Fatigue resistance of weld ends – Analysis of the notch stress using real geometry

Kaffenberger¹,

Vormwald

2011

Fatigue resistance of weld ends -Analysis of the notch stress using real geometry Schwingfestigkeit von Schweißnahtenden -Berechnung der Kerbspannungen mittels der realen Nahtgeometrie Dedicated to Prof. Holger Hanselka on the occasion of his 50 th birthday. M. Kaffenberger, M. VormwaldModern welded structures often contain weld start and end points which are the failure critical location. In particular, for special investigations into thin sheet structures, no approach for the determination of the fatigue life has been established thus far. In this research, the primary aim was to obtain the real geometry of weld ends with high precision using a three dimensional scanner to find a general approach using the notch stress concept. Going one step further, analyses have been performed regarding to unify the notch stress concept. The existing results of Olivier -who examined long welds with no start and end points -were re-evaluated to unify the results of long regular welds with the local weld end under one scatter band.

“…Allerdings liegen hier nur Erfahrungen an dickeren Blechen zugrunde (t F 5mm). Zwar wurden von [4] bereits Untersuchungen an dünnen Blechen mit Schweißnahtenden durchgeführt, jedoch liegen hier keinerlei Informationen vor, wie die Einwirkungen für eine zugehörige Wöhlerlinie bestimmt werden müssen.…”

Section: Introductionunclassified

Application of the notch stress concept to the real geometry of weld end points

Kaffenberger¹,

Vormwald²

2011

Application of the notch stress concept to the real geometry of weld end points The process used to manufacture modern weld structures often lead to weld start and end points. Under cyclic loading, crack initiation occurs predominantly at the weld start. In particular, for special investigations into thin sheet structures, no approach for the determination of the fatigue life has been established thus far. Therefore, in this research, we have attempted to find a general approach for the assessment of weld ends using the notch stress concept.The primary aim was to obtain the real geometry of weld ends with high precision using a three dimensional scanner. We were able to find an idealised weld end model with the mean toe radius of r = 0,2 mm that provides almost the same notch stresses like the real geometry. The applied load cases were longitudinal and transverse tension as well as bending. The crack always occurs at the weld toe. The notch stress S-N-curve was derived from the fatigue life of the cyclic testing so that the assessment of weld ends is possible for the first time. Moreover, some conversion rules have been developed so that the idealised weld end geometry can be modelled with an arbitrary toe radius. Going one step further, some analyses have been performed regarding to unify the notch stress concept. The existing results of Olivier -who examined long welds with no start and end points -were re-evaluated to unify the results of long regular welds with the local weld end under one scatter band. Using the scanned geometry a good agreement could be achieved. The use of an idealised model will be validated soon.