Cross section design of holey optical fibers with coating based on stress analysis in tension

In this paper, the mechanical behavior of newly developed holey optical fibers with and without coating was investigated by numerical analysis. Based on experimental work, the tensile failure characteristics were observed. The stress characteristics of some typical holey fibers with different section design were studied though the finite element method under tensile load. The optimum design of air hole arrangements and sizes were proposed according to the numerical results. The influence of the coating thickness on the axial stress of holey optical fiber was also investigated. The numerical results and conclusions will be useful for the cross section optimum design of holey optical fiber for increase its strength

Shear response behavior of STF/kevlar composite fabric in picture frame test

The picture frame test was applied to compare Kevlar neat and STF/Kevlar composite fabrics. The digital image correlation markers method was applied to measure the shear deformation behavior of the fabric in real-time under three loading rates: 100, 500, and 1000 mm/min. A theoretical model was applied to evaluate the effect of STF on the shear deformation stiffness of the fabric and cells and on the energy absorption during shear deformation. The results show that the STF/Kevlar composite fabric has a larger load-carrying capacity than the neat fabric in the picture frame test, and has obvious loading rate dependence. The yarn cell of the fabric undergoes slip deformation and reaches a shear-locked state; the shear modulus and the cell spring torsion coefficient of the STF/Kevlar composite fabric are significantly higher than those of neat fabric. The shear thickening behavior of STF occurs at higher loading rates, and the composite fabric has the highest shear deformation stiffness and shear energy absorption level

A 27-country test of communicating the scientific consensus on climate change.

peer reviewedCommunicating the scientific consensus that human-caused climate change is real increases climate change beliefs, worry and support for public action in the United States. In this preregistered experiment, we tested two scientific consensus messages, a classic message on the reality of human-caused climate change and an updated message additionally emphasizing scientific agreement that climate change is a crisis. Across online convenience samples from 27 countries (n = 10,527), the classic message substantially reduces misperceptions (d = 0.47, 95% CI (0.41, 0.52)) and slightly increases climate change beliefs (from d = 0.06, 95% CI (0.01, 0.11) to d = 0.10, 95% CI (0.04, 0.15)) and worry (d = 0.05, 95% CI (-0.01, 0.10)) but not support for public action directly. The updated message is equally effective but provides no added value. Both messages are more effective for audiences with lower message familiarity and higher misperceptions, including those with lower trust in climate scientists and right-leaning ideologies. Overall, scientific consensus messaging is an effective, non-polarizing tool for changing misperceptions, beliefs and worry across different audiences

Product market competition returns to skill and wage inequality

This paper shows that increasing product market competition can have a direct impact on the employment relationship and on wage inequality. I develop a simple model in which an increase in product market competition increases returns to skill through the effect of competition on the sensitivity of profits to cost reductions. I then show empirically that relative wages increase with competition using a large panel of United Kingdom workers with complete work histories. I identify the impact of competition on returns to skill in the panel, using two exogenous measures of competition provided by two quasi-natural experiments. Quantile regressions indicate that increased competition also raised returns to unobserved ability

Numerical analysis for the interlayer toughening of piezoelectric smart composite plate

The piezoelectric composite material could engender stress concentration resulting from small cracks during layers easily, as the cracks growth will lead to the failure of the whole structure. In this paper, a finite element model for piezoelectric composite materials by ABAQUS including interlayer crack was established, and the J integral and crack tip stress of different types PZT patches were calculated by using the equivalent integral method. Then, the J integral for adhesive layers with different thickness, elastic modulus considering and not considering piezoelectricity was investigated. The results show that the J integral of mode I, II reduces with thicker adhesive layer and lower elastic modules, and the J integral of mode II decreases more sharply than that of mode I

Effects of surface cracks and coating on fracture behaviour of microstructured silica optical fibers

The fracture behavior of microstructured silica optical fibers containing surface cracks in tension was investigated using a simplified 3D analysis. Strengthening caused by the polymer coating was considered to be associated with the closure stresses uniformly applied to the crack surfaces, which were generally created by the thermal mismatch between the coating resin and the silica glass. The stress intensity factor of the surface cracks in tension was evaluated with considering the crack configurations and surface coating. The effects of crack configurations and closure stresses on the failure loads were also discussed

Analysis of bending stiffness of honeycomb sandwich structure filled with foam

Abstract Based on the knowledge of material mechanics and elastic mechanics, the theoretical calculation formula of bending stiffness of honeycomb core filled with foamed rubber is derived in this paper. The rationality and feasibility of the theoretical formula are verified by finite element analysis of three-point bending model of honeycomb sandwich structure with or without foamed rubber. At the same time, the relative error between the bending stiffness value of finite element analysis and the theoretical value is controlled within 10%, which makes the calculation formula of theoretical value of filled foamed rubber honeycomb core have certain reference significance and application value.</jats:p