https://onlinelibrary.wiley.com/doi/pdf/10.1002/we.2661

The effect of resin uptake on the flexural properties of compression molded sandwich composites

Experimental and numerical study of high-order complex curvature mode shape and mode coupling on a three-bladed wind turbine assembly

Superhydrophobic surfaces have drawn attention from scientists and engineers because of their extreme water repellency. More interestingly, these surfaces have also demonstrated an infinite influence on civil engineering materials. In this feature article, the history of wettability theory is described firstly. The approaches to construct hierarchical micro/nanostructures such as chemical vapor deposition (CVD), electrochemical, etching, and flame synthesis methods are introduced. Then, the advantages and limitations of each method are discussed. Furthermore, the recent progress of superhydrophobicity applied on civil engineering materials and its applications are summarized. Finally, the obstacles and prospects of superhydrophobic civil engineering materials are stated and expected. This review should be of interest to scientists and civil engineers who are interested in superhydrophobic surfaces and novel civil engineering materials.

https://www.mdpi.com/2079-6412/9/11/753/pdf

Superhydrophobic Civil Engineering Materials: A Review from Recent Developments

The reduction of both energy consumption and production/maintenance costs in the industry requires the use of advanced engineering materials with remarkable features, including lightweight and long-term service life. As one of the advanced engineering materials, composites are widely applied in industry and civilian daily life. Nevertheless, there are some mechanical factors such as tensile strength restricting the application of such a material. To this end, this study is aimed to comprehensively review the recent research on the effects of fabrication characteristics on the tensile resistance of GFRP, CFRP, and AFRP composites. As revealed by recent progress, the epoxy resin is an advisable option for the production of high-performance polymeric composites due to the remarkable tensility, compression, and corrosion resistance. However, the high cost of epoxy resin is not favorable for mass production. In hybrid composites, stacking sequence is a vital factor that determines the ultimate tensile strength. In terms of higher mechanical performance, some researchers suggested using Kevlar fibers with woven orientation alongside the Carbon as axial fibers. At the same time, it is essential to carefully establish the value of fiber volume fraction. Otherwise, this can lead to dramatic internal defects such as agglomeration. In general, this review article was performed to investigate the impacts of composite fabrication characteristics such as fabrication method, reinforcing fibers orientation, fiber type, matrix phase type, and volume fraction of reinforcing phase on the tensile properties of composites used in aerospace, military, civil constructions, and automotive applications. In addition, the authors tried their best to make this research a credible source in the field of mechanical properties of CFRP, GFRP, and AFRP composites for future studies of other researchers. 

A review on fabrication techniques and tensile properties of glass, carbon, and Kevlar fiber reinforced rolymer composites

Polyimide aerogel with controlled porosity: Solvent-induced synergistic pore development during solvent exchange process

Debonding at the core–skin interphase region is one of the primary failure modes in core sandwich composites under shear loads. As a result, the ability to characterize the mechanical properties at the interphase region between the composite skin and core is critical for design analysis. This work intends to use nanoindentation to characterize the viscoelastic properties at the interphase region, which can potentially have mechanical properties changing from the composite skin to the core. A sandwich composite using a polyvinyl chloride foam core covered with glass fiber/resin composite skins was prepared by vacuum-assisted resin transfer molding. Nanoindentation at an array of sites was made by a Berkovich nanoindenter tip. The recorded nanoindentation load and depth as a function of time were analyzed using viscoelastic analysis. Results are reported for the shear creep compliance and Young’s relaxation modulus at various locations of the interphase region. The change of viscoelastic properties from higher values close to the fiber composite skin region to the smaller values close to the foam core was captured. The Young’s modulus at a given strain rate, which is also equal to the time-averaged Young’s modulus across the interphase region was obtained. The interphase Young’s modulus at a loading rate of 1 mN s−1 was determined to change from 1.4 GPa close to composite skin to 0.8 GPa close to the core. This work demonstrated the feasibility and effectiveness of nanoindentation-based interphase characterizations to be used as an input for the interphase stress distribution calculations, which can eventually enrich the design process of such sandwich composites.

/pdf/nanoindentation-measurement-of-core-skin-interphase-3gg3ogy1dh.pdf

Nanoindentation measurement of core–skin interphase viscoelastic properties in a sandwich glass composite

A family of ambient-dried polybenzoxazine aerogels is prepared with a facile and scalable process as a high-performance polymeric aerogel with strong and robust thermomechanical properties at eleva...

Low-Cost, Ambient-Dried, Superhydrophobic, High Strength, Thermally Insulating, and Thermally Resilient Polybenzoxazine Aerogels

Meta-Aerogels: Auxetic Shape-Memory Polyurethane Aerogels

The uniaxial compressive behavior of Colorado Mason sand at high strain rates was investigated on a split Hopkinson pressure bar. The sand grains were placed inside a hardened steel tube and end-capped by tungsten carbide rods. This assembly, with a desired bulk mass density for sand, was then sandwiched between incident and transmission bar ends for dynamic compression. Unsorted dry sand and partially saturated sand were impacted at high strain rates to determine the volumetric and deviatoric behavior. Quasi-static compression under the same confinement was also conducted to compare with the high strain rate data. The effect of initial mass density and moisture content level on the constitutive behavior was investigated. The constitutive behavior of dry sand was analyzed using a recently developed adaptive particle fracture algorithm implemented in the poly-ellipsoidal discrete element method, to further understand the mesoscale behavior of sand under high-rate compressive deformations.

Yao Ren

Papers

Nanoindentation measurement of core–skin interphase viscoelastic properties in a sandwich glass composite

The effect of resin uptake on the flexural properties of compression molded sandwich composites

Low-Cost, Ambient-Dried, Superhydrophobic, High Strength, Thermally Insulating, and Thermally Resilient Polybenzoxazine Aerogels

Meta-Aerogels: Auxetic Shape-Memory Polyurethane Aerogels

Constitutive behavior of granular materials under high rate of uniaxial strain loading