scholarly journals Mixed-mode cohesive zone parameters from integrated digital image correlation on micrographs only

2019 ◽  
Vol 156-157 ◽  
pp. 179-193 ◽  
Author(s):  
A.P. Ruybalid ◽  
J.P.M. Hoefnagels ◽  
O. van der Sluis ◽  
M.P.F.H.L. van Maris ◽  
M.G.D. Geers
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Cohesive Zone ◽  
Mixed Mode ◽  
Image Correlation ◽  
Zone Parameters ◽  
Integrated Digital Image Correlation

Damage Accumulation and Life-Prediction Models for SnAgCu Leadfree Electronics Under Shock-Impact

2009 ◽  
Author(s):  
Pradeep Lall ◽  
Sandeep Shantaram ◽  
Arjun Angral ◽  
Mandar Kulkarni ◽  
Jeff Suhling
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Thermal Aging ◽  
Cohesive Zone ◽  
Life Prediction ◽  
Failure Modes ◽  
Damage Index ◽  
Image Correlation ◽  
Shock Impact ◽  
Cohesive Zone Elements

Relative damage-index based on the leadfree interconnect transient strain history from digital image correlation, explicit finite-elements, cohesive-zone elements, and component’s survivability envelope has been developed for life-prediction of two-leadfree electronic alloy systems. Life prediction of pristine and thermally-aged assemblies, have been investigated. Solder alloy system studied include Sn1Ag0.5Cu, and 96.5Sn3.5Ag. Transient strains during the shock-impact have been measured using digital image correlation in conjunction with high-speed cameras operating at 50,000 fps. Both the board strains and the package strains have been measured in a variety of drop orientations including JEDEC horizontal drop orientation, vertical drop orientation and intermediate drop orientations. In addition the effect of sequential stresses of thermal aging and shock-impact on the failure mechanisms has also been studied. The thermal aging condition used for the study includes 125°C for 100 hrs. The presented methodology addresses the need for life prediction of new lead-free alloy-systems under shock and vibration, which is largely beyond the state of art. Three failure modes have been predicted including interfacial failure at the copper-solder interface, solder-PCB interface, and the solder joint failure. Explicit non-linear finite element models with cohesive-zone elements have been developed and correlated with experimental results. Velocity data from digital image correlation has been used to drive the attachment degrees of freedom of the submodel and extract transient interconnect strain histories. Explicit finite-element sub-modeling has been correlated with the full-field strain in various locations, orientations, on both the package and the board-side. The survivability of the leadfree interconnections under sequential loading (thermal aging and shock-impact) from simulation has been compared with pristine circuit assemblies subjected to shock-impact. Sequential loading changes the failure modes and decreases the drop reliability as compared to the room temperature experimental results. Damage index based survivability envelope is intended for component integration to ensure reliability in harsh environments.

scholarly journals Investigation by Digital Image Correlation of Mixed Mode I and II Fracture Behavior of Metallic IASCB Specimens with Additive Manufactured Crack-Like Notch

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 400 ◽  
Author(s):  
Ivo Campione ◽  
Tommaso Maria Brugo ◽  
Giangiacomo Minak ◽  
Jelena Janković Tomić ◽  
Nebojša Bogojević ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Selective Laser Sintering ◽  
Local Stress ◽  
Fatigue Loading ◽  
Image Correlation ◽  
Mode I ◽  
Displacement Fields

This work investigates the fracture behavior of maraging steel specimens manufactured by the selective laser sintering (SLS) technology, in which a crack-like notch (sharp notch) was directly produced during the additive manufacturing (AM) process. For the evaluation of the fracture toughness, the inclined asymmetrical semi-circular specimen subjected to three points loading (IASCB) was used, allowing to cover a wide variety of Mode I and II combinations. The effectiveness of manufacturing crack-like notches via the SLS technique in metals was evaluated by comparing the obtained experimental results with the ones obtained with pre-cracks induced by fatigue loading. The investigation was carried out by using the digital image correlation (DIC) technique, that allowed the evaluation of the full displacement fields around the crack tip. The displacement field was then used to compute the stress intensity factors (SIFs) for various combinations of Mode I and II, via a fitting technique which relies on the Williams’ model for the displacement. The SIFs obtained in this way were compared to the results obtained with the conventional critical load method. The results showed that the discrepancy between the two methods reduces by ranging from Mode I to Mode II loading condition. Finally, the experimental SIFs obtained by the two methods were described by the mixed mode local stress criterium.

scholarly journals Identification and Prediction of Mixed-Mode Fatigue Crack Path in High Strength Low Alloy Steel

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 504
Author(s):  
Jie Zhang ◽  
Cedric Kiekens ◽  
Stijn Hertelé ◽  
Wim De Waele
Keyword(s):  
Fatigue Crack ◽  
Digital Image Correlation ◽  
Crack Propagation ◽  
Digital Image ◽  
Mixed Mode ◽  
Standardized Test ◽  
Crack Tip ◽  
Shear Loading ◽  
Image Correlation ◽  
Crack Trajectory

The trajectory of fatigue crack growth is influenced by many parameters and can be irregular due to changes in stress distribution or in material properties as the crack progresses. Images of the surface of a standardized test specimen can be used to visualize the crack trajectory in a non-destructive way. Accurately identifying the location of the crack tip, however, is challenging and requires devoted image postprocessing. In this respect, digital image correlation allows to obtain full field displacement and strain fields by analysing changes of digital images of the same sample at different stages of loading. This information can be used for the purpose of crack tip tracking. This paper presents a combined experimental-numerical study of detection and prediction of fatigue crack propagation path by means of digital image correlation (DIC) and the extended finite element method (X-FEM). Experimental validation and analyses are carried out on a modified C(T) specimen in which a curved crack trajectory is triggered by introducing mixed-mode (tension + shear) loading. The developed tools are used for validating an automated framework for crack propagation prediction.

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