Multiscale Modeling for Damage Analysis
The increased computational power and programming capabilities in recent years have given impetus to the so-called multiscale modeling, which implements the largely intuitive notion that physical phenomena occurring at a lower length or size scale determine the observed response at a higher scale. A logical outcome of this thought is an organization of differentiated scales – from the lowest, such as nanometer scale, to the highest scale typical of the part or structure in mind – giving a hierarchy of scales. Working up the scales produces a hierarchical multiscale modeling, in which the essential challenge consists of “bridging” the scales. The simulation techniques, such as molecular dynamics simulation (MDS), succeed mostly in revealing phenomena from one scale to the next; but proceeding to three or more scales often necessitates unrealistic computing power even with the most versatile facilities available. In addition, the limitation of independent physical validation of the simulated results questions the wisdom of total reliance on the multiscale hierarchical modeling strategy. When it comes to subcritical (prefailure) damage in composites, the multiscale modeling concept needs closer examination, firstly, because the length scales of constituents and heterogeneities are fixed while those of damage evolve progressively, and secondly, because the mechanisms of damage tend to segregate in modes with individual characteristic scales. All this is the subject of this chapter, which will first describe and clarify the damage mechanisms in common types of composites followed by the induced response observed at the macroscale. The hierarchical modeling approach will be discussed against this knowledge; and a different approach, named synergistic multiscale modeling, will be advocated. Assessment will be offered of the current state of this modeling, and future activities aimed at accomplishing its objectives will be outlined.
KeywordsRepresentative Volume Element Composite Laminate Multiscale Modeling Crack Opening Displacement Transverse Crack
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