Photonic crystals (PCs) with controllable lattice structures, photonic bandgaps, and brilliant colors are fabricated by the self‐assembly of the monodispersed anisotropic metal–organic framework (MOF) ZIF‐8 particles into long‐range ordered superstructures. The shape parameter (m) of the particles is used to quantify to what degree the particle shape has deformed from that of a perfect sphere (m = 2) and that of a perfect cube (m = ∞). It is experimentally proven that m value is the key for controlling the lattice structures. Three PCs with different m values of ZIF‐8 particles (9.7, 4.7, and 2.5) are found to be simple cubic, rhombohedral, and face‐centered‐cubic structures, respectively. Different from the conventional spherical particles‐based PCs, brilliant colors can be generated from the second‐order diffraction of the nonspherical MOFs‐based PCs. Taking advantage of this unique characteristic, a new information encryption technology is developed by combing the first‐order diffraction of rhombohedral PCs and first‐second‐order diffraction of simple‐cubic PCs. This work paves a way to explore nonspherical particle‐based PCs materials with different crystal forms and provides a new insight in novel optical characteristics of the PCs, which will promote their applications in anticounterfeiting, color displays, and printings.
Stainless steel single sink with countertop (SC) has the characteristics of large depth and asymmetric countertop. Its traditional stamping process is mainly realized by the combination of multi-stage deep drawing and annealing process, which leads to the complex manufacturing process, long production chain and poor consistency of products. Based on finite element analysis software (Dynaform) with nonlinear dynamic display algorithm, numerical simulation analysis and research are carried out on the parameters of hydrodynamic deep drawing. First, the sink and the part of countertop are preformed into a cylinder shell, and then the excess of the cylinder shell is drawn back to the countertop. The research results show that the hydrodynamic deep drawing process can effectively improve the flow uniformity of stainless steel sheet, increase the forming of stainless steel tank, drawing a more uniform wall thickness, thus effectively improve the quality of single tank with countertop by setting up reasonable preform structure, controlling the liquid pressure and its loading paths and blank-holder force.
By means of numerical simulation and experimental, the liquid filling forming process of an aluminum alloy double concave and convex curved sheet part was studied. The quality of forming parts, especially the thinning rate, is compared and studied during different hydroforming process. The results show that the thinning rate of the product is more than 25% regardless of the passive or active liquid filling drawing. However, the maximum thinning rate of the product is less than 20% when the hybrid hydroforming is carried out in a set of die with passive liquid filling in sequence, followed by pulsating reverse liquid filling. The method has reference significance for improving the forming quality of the parts with concave and convex surface of thin plate.
In this work, a variable thickness tube blank geometry is proposed to be used in T-shaped tube hydroforming. The dimensions of the tube blank are optimized by the response surface method (RSM) linked with finite element simulation during T-shaped tube hydroforming. The influence of the wall thickness, angle and length of the tube blank are discussed on the thinning ratio and branch height. Multi-objective functions that relate objectives and design variables are formulated. Furthermore, the design variables having greatest impact on the objectives are obtained by sensitivity analysis. The optimal the geometric dimensions are determined within the given criterion by RSW and desirability approach. The optimized results have good agreement with the obtained results by finite element simulation and experiment.
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