scholarly journals Reliability analysis of girth welds by using finite element simulations with uncertain material properties

2021 ◽  
Vol 1043 (3) ◽  
pp. 032071
Author(s):  
Cheng Qian ◽  
Jin Xiao Meng ◽  
Yi Ren ◽  
Bo Sun ◽  
Qiang Feng ◽  
...  
Keyword(s):  
Finite Element ◽  
Reliability Analysis ◽  
Material Properties ◽  
Finite Element Simulations ◽  
Girth Welds ◽  
Uncertain Material Properties

Analysis of Chip Damage Risk in Thermosonic Wire Bonding

2011 ◽  
Vol 478 ◽  
pp. 75-80 ◽  
Author(s):  
Christian Dresbach ◽  
Georg Lorenz ◽  
Matthias Petzold ◽  
Holm Altenbach
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Electron Backscatter Diffraction ◽  
Copper Wire ◽  
Diffraction Method ◽  
Dielectric Materials ◽  
Finite Element Simulations ◽  
Flat Punch ◽  
Extreme Change ◽  
Damage Risk

In current highly integrated microelectronic devices including system-in-package and stacked-die solutions, system reliability is strongly influenced by reliability of the gold and copper wire bond interconnections. Especially in state-of-the-art ICs containing mechanically sensitive low-K dielectric materials, controlling the mechanical properties of the free air ball (FAB) is of utmost significance due to chip damage risks during the bond process. Because of an extreme change in microstructure when forming the FAB, the material properties change significantly. Consequently, it is necessary to determine the properties of the FAB itself, when analyzing chip damage risks via finite element simulations. We present a micro-compression test that allows the determination of the hardening behavior of typical gold and copper FABs with diameters between 45 µm and 75 µm. In this test a FAB is placed on a diamond support or a test capillary and loaded by a diamond flat punch in a microindenter. The hardening was determined from force/displacement behavior via parameter identification using finite element simulations. The identified yield stresses correlate very well with the microstructure which was determined by electron backscatter diffraction method; this means that the yield stress decreases with increasing mean grain diameter in analogy to the Hall-Petch correlation. Compared to unprocessed wires the initial yield stresses are 50% to 60% lower. Considering these material properties, the damage risk during bonding on complex bond pad layouts can be predicted more realistically. This can be shown by results of real bond structures.

scholarly journals Analytic analysis of auxetic metamaterials through analogy with rigid link systems

2018 ◽  
Vol 474 (2210) ◽  
pp. 20170753 ◽  
Author(s):  
Daniel Rayneau-Kirkhope ◽  
Chengzhao Zhang ◽  
Louis Theran ◽  
Marcelo A. Dias
Keyword(s):  
Finite Element ◽  
Mechanical Behaviour ◽  
Material Properties ◽  
Threshold Value ◽  
Finite Element Simulations ◽  
Elastic Instability ◽  
Lattice Systems ◽  
Rigid Link ◽  
Post Buckling ◽  
Insight Into

In recent years, many structural motifs have been designed with the aim of creating auxetic metamaterials. One area of particular interest in this subject is the creation of auxetic material properties through elastic instability. Such metamaterials switch from conventional behaviour to an auxetic response for loads greater than some threshold value. This paper develops a novel methodology in the analysis of auxetic metamaterials which exhibit elastic instability through analogy with rigid link lattice systems. The results of our analytic approach are confirmed by finite-element simulations for both the onset of elastic instability and post-buckling behaviour including Poisson’s ratio. The method gives insight into the relationships between mechanisms within lattices and their mechanical behaviour; as such, it has the potential to allow existing knowledge of rigid link lattices with auxetic paths to be used in the design of future buckling-induced auxetic metamaterials.

Influence of the Bolt Material Properties on the Ultimate Capacity of End Plate Bolted Joint Subjected to Column Loss

2021 ◽  
Vol 885 ◽  
pp. 133-139
Author(s):  
Roberto Tartaglia ◽  
Alessia Campiche
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Material Properties ◽  
Finite Element Simulations ◽  
Material Strength ◽  
Bolted Joint ◽  
Ultimate Capacity ◽  
Catenary Action ◽  
Beneficial Effects ◽  
End Plate

This paper investigates the performance of extended stiffened end-plate bolted beam-to-column joints subjected a column loss scenario by means of finite element simulations. An advanced numerical model was developed, and its effectiveness was validated against the experimental results. The influence of the bolt strengthening on the column loss action was investigated changing the grade of bolts. The results showed that the joint performance under column loss scenario are deeply related to the development of the catenary action that depends from the connection ductility; therefore increasing the bolt material strength will provide beneficial effects on the joint capacity under the column loss.

Advanced stochastic finite element simulations and reliability analysis

2014 ◽  
Author(s):  
Δημήτριος Γιοβάνης
Keyword(s):  
Finite Element ◽  
Monte Carlo ◽  
Reliability Analysis ◽  
Response Function ◽  
Finite Element Simulations ◽  
Stochastic Finite Element ◽  
Variability Response Function

Στα πλαίσια της παρούσας διδακτορικής διατριβής, για την αντιμετώπιση του υπολογιστικού κόστους που έχει η μέθοδος προσομοίωσης Monte Carlo, αναπτύχθηκαν αρχικά δύο μεθοδολογίες για τον υπολογισμό της πιθανότητας αστοχίας ενός στοχαστικού συστήματος. Στην πρώτη μεθοδολογία τα τεχνητά νευρωνικά δίκτυα χρησιμοποιούνται στο πλαίσιο της μεθόδου των υποσυνόλων ενώ στη δεύτερη μέθοδο τα νευρωνικά δίκτυα χρησιμοποιούνται στο πλαίσιο της μεθόδου Monte Carlo. Οι δύο αυτές μέθοδοι είχαν ως αποτέλεσμα τη μείωση του υπολογιστικού κόστους τόσο της μεθόδου των υποσυνόλων όσο και της Monte Carlo. Στη συνέχεια πραγματοποιήθηκε μία προσαρμοστική διατύπωση της μεθόδου των φασματικών πεπερασμένων με μεθόδους Galerkin χρησιμοποιώντας τη μέθοδο διακύμανσης της απόκρισης (Variability response function) για τη χωρική κατανομή των όρων της Karhunen-Loeve στοιχείων η οποία βελτιώνει την υπολογιστική απόδοση της μεθόδου. Η μέθοδος αυτή οδηγεί σε μείωση της πυκνότητας των διευρυμένων μητρώων η οποία με τη χρήση επαναληπτικών μεθόδων επίλυσης οδηγεί σε μείωση του υπολογιστικού κόστους. Τέλος, πραγματοποιήθηκε μία παραμετρική διερεύνηση της συμπεριφοράς της μεθόδου των Φασματικών πεπερασμένων στοιχείων για διάφορες τιμές παραμέτρων του στοχαστικού πεδίου οποία μπορεί να χρησιμοποιηθεί στα πλαίσια της εκτίμησης της υπολογιστικής συμπεριφοράς της μεθόδου σε σχέση με τη μέθοδο Monte Carlo.

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