16789 research outputs found
Sort by
The Effects of Lamina Stacking Sequence on the Structural Response of Composite Laminates
No full textComposites are lightweight engineered materials made of fiber and matrix. The fiber acts as the reinforcement, while the matrix holds the fibers together. Fiber-reinforced composite laminates are prepared by stacking single sheets of continuous fibers, called lamina or ply, in different orientations to achieve the desired strength and stiffness. The Lamina Stacking Sequence (LSS) represents the order these layers are stacked in a composite laminate. This research aims to numerically and experimentally investigate the effects of LSS on the structural response of composite laminates. For example, the [0/45/-45]s laminate represents a symmetric composite plate consisting of 6 laminae stacked at 0, 45, -45, -45, 45 and 0 degree orientations. These orientations ([0/45/-45]s, [0/-45/45]s, [45/-45/0]s, [-45/45/0]s, [45/0/-45]s, and [-45/0/45]s) represent the same laminate but with different LSS. In our research, we performed numerical simulations using the finite element analysis software ANSYS to study the structural response of a composite laminate defined by [0/45/-45]s with several LSS. We used the material properties of graphite and epoxy to simulate the fiber and matrix, respectively. These laminates were subjected to axial and bending loads to observe their structural response. Each laminate experienced the same stress and deformation when subjected to axial loads, but the results varied between LSS when subjected to bending loads. To verify these results, we performed experiments by printing composite laminates using PETG embedded with chopped carbon fiber. The tensile response of these laminates was found to be mostly consistent and invariant with LSS under axial loading
Helitrons are enriched in lichenized fungi with long generation length and small distribution sizes
No full textMobile genetic elements (MGEs) have the potential to drive genome evolution by introducing mutations and causing structural instability and chromosomal rearrangements, particularly under conditions like environmental or genetic stress. In this study, we generated 18 new long-read reference genomes for lichenized fungi, which form obligate mutualistic symbioses with algae or a cyanobacteria. We used these genomes to investigate the connections between dominant reproductive mode, distribution size, and generation length with the abundance and spatial distribution of MGEs for 28 lichenized fungal reference genomes using a phylogenetic comparative framework. We found that species with smaller distribution sizes and those with longer generation lengths had a higher genomic DNA transposon load, and that their genomes were enriched with Rolling Circle transposons, specifically, which contradicts broad patterns identified in previous studies of MGEs in rare species. Disproportionate distributions of MGEs in rare and range-restricted species may disrupt genomic stability, decrease fitness, and be reflective of species experiencing a greater degree of stress. Also, greater MGE activity may be an important source of novel genetic diversity in isolated populations with limited gene flow. Further research is needed to understand the potential mechanisms driving MGE proliferation in these genomes, and if MGE content is predictive of increased extinction risk in rare species
