TY  - JOUR
A1  - Nagel, Falk
A1  - Simon, Flaviu
A1  - Kümmel, Benjamin
A1  - Bergmann, Jean Pierre
A1  - Hildebrand, Jörg
T1  - Optimization Strategies for Laser Welding High Alloy Steel Sheets
JF  - Physics Procedia
N2  - A known phenomenon during laser welding of thin sheets is the deformation caused by thermally induced stresses. This deformation can result in a change of the gap width between the welded parts, which leads to an unstable welding process. Inducing displacements by using a second heat source will compensate for the change in gap width, hence optimizing the welding process. The base material is 1 mm thick austenitic stainless steel 1.4301, which is welded by a CO2 laser. The second heat source is a diode laser. The gap between the welded parts was set between 0.05 mm and 0.1 mm. The influence of the second heat source on the welding process and the welding result is described. The usage of a second heat source allows a higher gap width to be set prior to the welding process. The results of the numerical simulation were found to be corresponding to those of the experiments.
KW  - Edelstahl
KW  - Laserschweißen
KW  - Laser Welding; CO2; Diode; Distortion; Finite Element Analysis; Thermal Analysis; Mechanical Analysis; Numerical Model
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170425-31554
SP  - 1242
EP  - 1251
ER  - 
TY  - JOUR
A1  - Motra, Hem Bahadur
A1  - Hildebrand, Jörg
A1  - Dimmig-Osburg, Andrea
T1  - Assessment of strain measurement techniques to characterise mechanical properties of structural steel
JF  - Engineering Science and Technology, an International Journal
N2  - Strain measurement is important in mechanical testing. A wide variety of techniques exists for measuring strain in the tensile test; namely the strain gauge, extensometer, stress and strain determined by machine crosshead motion, Geometric Moire technique, optical strain measurement techniques and others. Each technique has its own advantages and disadvantages. The purpose of this study is to quantitatively compare the strain measurement techniques. To carry out the tensile test experiments for S 235, sixty samples were cut from the web of the I-profile in longitudinal and transverse directions in four different dimensions. The geometry of samples are analysed by 3D scanner and vernier caliper. In addition, the strain values were determined by using strain gauge, extensometer and machine crosshead motion. Three techniques of strain measurement are compared in quantitative manner based on the calculation of mechanical properties (modulus of elasticity, yield strength, tensile strength, percentage elongation at maximum force) of structural steel. A statistical information was used for evaluating the results. It is seen that the extensometer and strain gauge provided reliable data, however the extensometer offers several advantages over the strain gauge and crosshead motion for testing structural steel in tension. Furthermore, estimation of measurement uncertainty is presented for the basic material parameters extracted through strain measurement.
KW  - Baustahl
KW  - Werkstoffprüfung
KW  - Zugversuch
KW  - Affecting factors; Measurement uncertainty; Materials testing; Quantitative comparison; Strain comparison; Tensile test
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170425-31540
SP  - 260
EP  - 269
ER  -