Voids are common defects in 3D woven composites because of the complicated manufacturing processes of the composites. In this study, a micro–meso multiscale analysis was conducted to evaluate the influence of voids on the mechanical properties of three-dimensional orthogonal woven composites. Statistical analysis was implemented to calculate the outputs of models under the different scales. A method is proposed to generate the reasonable mechanical properties of the microscale models considering randomly distributed voids and fiber filaments. The distributions of the generated properties agree well with the calculated results. These properties were utilized as inputs for the mesoscale models, in which void defects were also considered. The effects of these defects were calculated and investigated. The results indicate that tensile and shear strengths were more sensitive to the microscale voids, while the compressive strength was more influenced by mesoscale voids. The results of this study can provide a design basis for evaluating the quality of 3D woven composites with void defects.
An alternative hybrid time-frequency domain approach based on the fast iterative shrinkagethresholding algorithm (FISTA) is presented for rotating acoustic source identification. This approach is similar to the existing approaches based on the deconvolution approach for the mapping of acoustic sources (DAMAS) and non-negative least squares (NNLS) without the sample interpolation of sound pressure signal in the time domain. The acoustic source is first identified using the time-domain tracking Delay and Sum (DAS) method. The Frequency-domain deconvolution is then performed to attenuate the sidelobes and improve the spatial resolution. The simulation and experimental results indicate that the proposed approach is robust to the sampling rate and enjoys the good spatial convergence and resolution, effective sidelobe suppression, accurate quantification, as well as high computational efficiency. In general, at a low time-domain sampling rate, the proposed approach outperforms the DAMAS-or NNLS-based hybrid time-frequency domain approaches without the sample interpolation of sound pressure signal in the time domain. INDEX TERMS Rotating acoustic source identification, hybrid time-frequency domain approach, fast iterative shrinkage-thresholding algorithm.
The present work aims to study the effect of nano-TiO 2 modified epoxy on the tension, compression, and fracture toughness properties of nano-doped polymer (NP) and nano-doped 3D woven (NW) composites. Nanoparticles are dispersed into epoxy using high-speed shear mixing and ultrasonication processes. Vacuum-assisted resin infusion molding process is utilized to prepare the woven composites. The results indicate that nanoparticle addition can
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.