Meta-sandwich composites with three-dimensional(3D)printed architecture structure are characterized by their high ability to absorb energy.In this paper,static and fatigue 3-point bending tests are implemented on a 3D...Meta-sandwich composites with three-dimensional(3D)printed architecture structure are characterized by their high ability to absorb energy.In this paper,static and fatigue 3-point bending tests are implemented on a 3D printed sandwich composites with a re-entrant honeycomb core.The skins,core and whole sandwich are manufactured using the same bio-based material which is polylactic acid with flax fiber reinforcement.Experimental tests are performed in order to evaluate the durability and the ability of this material to dissipate energy.First,static tests are conducted to study the bending behaviour of the sandwich beams,as well as to determine the failure parameters and the characteristic used in fatigue tests.Then,fatigue analyses were carried out to determine the fatigue resistance of these structures.The effects of the core density on the stiffness,hysteresis loop,energy absorption and loss factor,for two loading level,are determined.Moreover,the behaviour of this sandwich composite with re-entrant honeycomb core is compared with that of sandwiches with different core topologies.The results show that sandwich with high core density dissipate more energy,which results higher loss factors.The determined properties offer the most sensitive indicators of sandwich composite damage during its lifetime.This work aims to determine the static and fatigue properties of this material,thus,study its potential applications in industry.展开更多
Digital holography(DH)has emerged as one of the most effective coherent imaging technologies.The technological developments of digital sensors and optical elements have made DH the primary approach in several research...Digital holography(DH)has emerged as one of the most effective coherent imaging technologies.The technological developments of digital sensors and optical elements have made DH the primary approach in several research fields,from quantitative phase imaging to optical metrology and 3D display technologies,to name a few.Like many other digital imaging techniques,DH must cope with the issue of speckle artifacts,due to the coherent nature of the required light sources.Despite the complexity of the recently proposed de-speckling methods,many have not yet attained the required level of effectiveness.That is,a universal denoising strategy for completely suppressing holographic noise has not yet been established.Thus the removal of speckle noise from holographic images represents a bottleneck for the entire optics and photonics scientific community.This review article provides a broad discussion about the noise issue in DH,with the aim of covering the best-performing noise reduction approaches that have been proposed so far.Quantitative comparisons among these approaches will be presented.展开更多
文摘Meta-sandwich composites with three-dimensional(3D)printed architecture structure are characterized by their high ability to absorb energy.In this paper,static and fatigue 3-point bending tests are implemented on a 3D printed sandwich composites with a re-entrant honeycomb core.The skins,core and whole sandwich are manufactured using the same bio-based material which is polylactic acid with flax fiber reinforcement.Experimental tests are performed in order to evaluate the durability and the ability of this material to dissipate energy.First,static tests are conducted to study the bending behaviour of the sandwich beams,as well as to determine the failure parameters and the characteristic used in fatigue tests.Then,fatigue analyses were carried out to determine the fatigue resistance of these structures.The effects of the core density on the stiffness,hysteresis loop,energy absorption and loss factor,for two loading level,are determined.Moreover,the behaviour of this sandwich composite with re-entrant honeycomb core is compared with that of sandwiches with different core topologies.The results show that sandwich with high core density dissipate more energy,which results higher loss factors.The determined properties offer the most sensitive indicators of sandwich composite damage during its lifetime.This work aims to determine the static and fatigue properties of this material,thus,study its potential applications in industry.
基金support under Grant NSF/IIS-1422179Grant NSF ECCS 1545687.
文摘Digital holography(DH)has emerged as one of the most effective coherent imaging technologies.The technological developments of digital sensors and optical elements have made DH the primary approach in several research fields,from quantitative phase imaging to optical metrology and 3D display technologies,to name a few.Like many other digital imaging techniques,DH must cope with the issue of speckle artifacts,due to the coherent nature of the required light sources.Despite the complexity of the recently proposed de-speckling methods,many have not yet attained the required level of effectiveness.That is,a universal denoising strategy for completely suppressing holographic noise has not yet been established.Thus the removal of speckle noise from holographic images represents a bottleneck for the entire optics and photonics scientific community.This review article provides a broad discussion about the noise issue in DH,with the aim of covering the best-performing noise reduction approaches that have been proposed so far.Quantitative comparisons among these approaches will be presented.
