A new polyurethane-steel honeycomb composite pier anti-collision device: Concept and compressive behavior

A new type of pier anti-collision composite structure composed of honeycomb steel and polyurethane (PU) elastomer was proposed in this study. The impacts of the shape and filling materials of inner core cells on the failure mode, load–displacement cure, bearing capacity, structural stability, and energy absorption were studied by conducting uniaxial compression tests on device segments. Test results showed that the bearing capacity, structural stability, and energy absorption of honeycomb steel structure were significantly improved by PU elastomer filling. Besides, when compared with the square honeycomb structure and the regular hexagon honeycomb structure, the maximum values of average load, total energy absorption (TEA), and specific energy absorption (SEA), which were 69.6 kN, 1986.1 J, and 1300 J/kg, respectively, for the regular triangle honeycomb structure without PU filling, increased to 459.3%, 376.38%, and 212.5%, respectively, for the regular hexagonal core cell structure with PU filling, which was proved to be the most suitable core structure for pier anti-collision device.

Two-dimensional bucking structure induces the ultra-low thermal conductivity: A comparative study of the group GaX (X = N, P, As)

With the successful synthesis of the two-dimensional (2D) gallium nitride (GaN) in a planar honeycomb structure, the phonon transport properties of 2D GaN have been reported. However, it still remains...

FEA and Quasi-static Test on Energy Absorption Characteristic of Space Orthogonal Concave Honeycomb Structure with Negative Poisson’s Ratio

As a representative of metamaterials, negative Poisson’s ratio (NPR) material possesses special mechanical properties such as expansion, negative compression ratio and so forth. As a result, it is widely used in the fields of vehicles, aerospace, et al. In this paper, a novel space orthogonal concave honeycomb structure (OC) is designed based on traditional concave honeycomb structure (CHS). In order to explore the influence rule of OC structure on the deformation and energy absorption capacity of crash box under low-speed collision, mechanical analysis and parameter research on OC structure are conducted through quasi-static compression test and numerical simulation. The results suggest that the finite element results of OC structure fit well with the experimental results, and the FEM is highly credible. In addition, the novel OC sandwich structure can effectively enhance the deformation capacity and improve the energy absorption performance of the crash box. When the wall thickness ? of OC structure is 1mm and angle ? is 50°, the deformation and energy absorption capacity of the crash box increased by 25.6% and 19.3% respectively.

Compression Behaviour of Bio-Inspired Honeycomb Reinforced Starfish Shape Structures Using 3D Printing Technology

The bio-inspired structure (e.g., honeycomb) has been studied for its ability to absorb energy and its high strength. The cell size and wall thickness are the main elements that alter the structural ability to withstand load and pressure. Moreover, adding a secondary structure can increase the compressive strength and energy absorption (EA) capability. In this study, the bio-inspired structures are fabricated by fused deposition modelling (FDM) technology using polylactic acid (PLA) material. Samples are printed in the shape of a honeycomb structure, and a starfish shape is used as its reinforcement. Hence, this study focuses on the compression strength and EA of different cell sizes of 20 and 30 mm with different wall thicknesses ranging from 1.5 to 2.5 mm. Subsequently, the deformation and failure of the structures are determined under the compression loading. It is found that the smaller cell size with smaller wall thickness offered a crush efficiency of 69% as compared to their larger cell size with thicker wall thickness counterparts. It is observed that for a 20 mm cell size, the EA and maximum peak load increase, respectively, when the wall thickness increases. It can be concluded that the compression strength and EA capability increase gradually as the cell size and wall thickness increase.

Micro-structural and compositional study: ε-Fe2O3 crystals in the Hare’s Fur Jian Ware

The Jian kilns in the present-day Jianyang county of Fujian province are well-known as their thick and lustrous black-glazed porcelain production. The hare’s fur (HF) glazed Jian wares characterized by radial fur-like strips, as one of the most typical representatives of black-glazed tea bowls, are originated from phase separation of glaze melt and crystallization of iron oxides. In this work, various techniques were performed on the yellowish-brown HF samples, including portable energy-dispersive X-ray fluorescence (PXRF), synchrotron X-ray absorption near-edge spectroscopy (XANES), optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy (RS). The objective of this study was to well understand the microstructure characteristics and chemical compositions of glaze patterns. Results showed that the main constituents of the ceramic glaze were alumina (10.61-16.43 wt.%), silica (62.20-77.07 wt.%), calcium (3.85-6.97 wt.%) and iron oxide (4.10-8.35 wt.%). The studies evidenced that the presence of metastable epsilon-hematite crystals (ε-Fe2O3) formed on the brownish yellow glazed surface. Microstructural analysis revealed that there were three types of crystal structures in the glaze surface, one consisted of well-grown leaf-like or dendritic-like structure with highly ordered branches at micrometers scales, one was comprised of flower-like clusters accompanied by branches radiating from the center, petals growing along the branches and needles on both sides of the petals, and the last embraced a honeycomb structure tightly packed with plentiful spherical or irregular-shaped particles. In addition, ε-Fe2O3 crystals in the cross-section of glaze showed a gradient distribution.

Refractory hypertension secondary to renal artery stenosis with a honeycomb-like structure

Background A honeycomb-like structure (HLS) is a rare abnormality characterized by a braid-like appearance. Angiograph and intravascular examination, including coherence tomography and intravascular ultrasound (IVUS), can further confirm the multiple intraluminal channels or honeycomb structure, which can also be described as looking like ‘swiss cheese’, a ‘spider web’ or a ‘lotus root’. Previous studies have mostly reported this abnormality in coronary arteries, with a few cases in renal arteries. More information about the characteristics and development of HLS is needed. Case presentation A 69-year-old Han man with resistant hypertension received abdominal enhanced computerised tomography and was revealed to have left renal artery stenosis with the possibility of left renal infarction. Renal artery angiography confirmed a 95% stenosis located in the proximal segment of the left renal artery, and the middle segment was blurred with multi-channel-like blood flow. Further IVUS was performed and identified multiple channels surrounded by fibrous tissue. It was a rare case of HLS in the renal artery secondary to the thrombus, with organisation and recanalisation. Balloon dilatation and stent implantation at the proximal segment of the left renal artery were performed successfully. Blood pressure was well controlled after the procedure. Conclusions The IVUS findings are helpful for forming interventional therapeutic strategies for HLS lesions in the renal artery.

Zero thermal expansion in metal-organic framework with imidazole dicarboxylate ligands

Exploring new abnormal thermal expansion materials is important to understand the nature of thermal expansion. Metal-Organic Framework (MOF) with unique structure flexibility is ideal material to study the thermal expansion. This work adopts the high-resolution variable-temperature powder X-ray diffraction to investigate the structure and intrinsic thermal expansion in Sr-MOF ([Sr(DMPhH2IDC)2]n). It has the unique honeycomb structure with 1D channels along c-axis direction, the a-b plane displays layer structure. The thermal expansion behavior has strong relationship with the structure, ZTE appears in the a-b plane and large PTE along c-axis direction. The possible mechanism is that the a/b layers have enough space for the transverse thermal vibration of polydentate ligands, while along the c-axis direction is not. This work not only reports one interesting zero thermal expansion material, but also provides new understand for thermal expansion mechanism from the perspective of structural model.