These gradients are fundamentally associated with the variations in local chemical compositions/ constituents and structural characteristics involved in the arrangement, distribution, dimensions and orientations of the building units.
Here, we review the basic design forms and principles of naturally-occurring gradients in biological materials and discuss the functions and benefits that they confer to organisms. The translation of such design motifs into synthetic materials offers a spectrum of feasible pathways towards unprecedented properties and functionalities that are favorable for practical uses in a variety of engineering and medical fields. Living organisms have ingeniously evolved functional gradients and heterogeneities to create high-performance biological materials from a fairly limited choice of elements and compounds during long-term evolution and selection. We discuss the important underlying fracture mechanisms using data collected from digital image correlation (DIC), digital image microscopy, and scanning electron microscopy (SEM), which were used to analyze the fracture surface.
Moreover, regardless of the gradient function used in the design of the specimens, decreasing the length of the transition zone from 100%W to 5%W increased the fracture resistance of FGMs. In contrast, FGMs with continuous gradients showed higher values of elastic stiffness and fracture energy, which makes each gradient function suitable for different loading scenarios. Among the composites with gradients, those with step-wise gradients showed a slightly better fracture resistance compared to those with continuous gradients. Additionally, it was found that specimens with abrupt hard-soft transitions have significantly better fracture properties than those with continuous gradients. The results showed that except for the fracture strain, the fracture properties of the graded specimens decreased as the length of the transition zone increased.
In addition, we changed the length of the transition zone between the hard and soft materials such that it covered 5%, 25%, 50%, or 100% of the width (W) of the specimens. We designed, additively manufactured, and mechanically tested the two main types of functionally graded composites, namely, composites with step-wise and continuous gradients.
#FRACTURE GLASS PRINTS INSPIRATION CRACK#
Here, using voxel-based multi-material additive manufacturing (AM, = 3D printing) techniques, which works on the basis of material jetting, we studied the fracture behavior of functionally graded soft-hard composites with a pre-existing crack colinear with the gradient direction. Functionally graded materials (FGMs) can effectively eliminate the interface problems in extremely hard-soft connections, and, thus, have numerous and diverse applications in high-tech industries, such as those in biomedical and aerospace fields. This concept can be implemented in the design and fabrication of advanced materials with specific functionalities and properties. The functional gradient is a concept often occurring in nature.
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