Experimental research and numerical simulation on vibration characteristics of a rectangular plate structure in fast time-varying thermal environments

Plate attitude control structures such as rudders and vertical tails of high-speed aircraft are faced with the compound effect of fast time-varying thermal environments and vibration during the high maneuvering flight. In this paper, a thermal/vibration test system was established by combining a transient aerodynamic heating simulation system with a vibration test system. A rectangular plate structure made of nickel-based stainless steel was tested at different heating rates and its modal frequencies in fast time-varying thermal environments were obtained. Numerical calculation was performed accordingly. The calculated results coincide well with the experimental results, verifying the credibility and effectiveness of the experimental methods. The research results can provide an important test method and reference basis for the dynamic performance analysis and safety design for the plate-like structures of high-speed aircraft in fast time-varying thermal environments

Toward fluid-structure-piezoelectric simulations applied to flow-induced energy harvesters

The subject deals with the simulation of flow-induced energy harvesters. We focus in particular on the modelling of autonomous piezo-ceramic power generators to convert ambient fluid-flow energy into electrical energy. The vibrations of an immersed electromechanical structure with large amplitude have to be taken into account in that case. One challenge consists in modelling and predicting the nonlinear coupled dynamic behaviour for the improved design of such devices. The set of governing equations is expressed in integral form, using the method of weighted residuals, and discretized with finite elements using the open source package FEniCS. Preliminary results of separated problems using FEniCS will be detailed and discussed (e.g. Navier-Stokes with or without moving meshes, nonlinear elasticity, aeroelasticity and electromechanical coupling). The objective is to validate each problem independently before coupling all the phenomena in a monolithic framework. Those simulations involve nonlinearities at many levels of modeling. The perspective of using reduced order models to limit the computational cost (in time and memory) will be discussed in an outlook to this work

Bis[(E)-4-bromo-2-(methoxy­imino­meth­yl)phenolato-κ2 N,O 1]copper(II)

In the title centrosymmetric mononuclear copper(II) complex, [Cu(C8H7BrNO2)2], the CuII atom, lying on an inversion centre, is four-coordinated in a trans-CuN2O2 square-planar geometry by two phenolate O atoms and two oxime N atoms from two symmetry-related N,O-bidentate oxime-type ligands. Inter­molecular C—H⋯O hydrogen bonds link neighbouring mol­ecules into a one-dimensional supra­molecular structure with an R 2 2(14) ring motif. This structure is further stabilized by π–π stacking inter­actions between adjacent benzene rings [centroid–centroid distance = 3.862 (1) Å]

Experimental investigation of high temperature thermal-vibration characteristics for composite wing structure of hypersonic flight vehicles

A thermal-vibration test system is established by combining the high-temperature transient heating simulation system and vibration test apparatus, and this system can carry out experimental research on the thermal modal of high-temperature-resistant composite wing structure of hypersonic flight vehicles under high temperature environment with 1100°C. The vibration signals of the composite wing structure in high-temperature environments are transmitted to non-high temperature field by using self-developed extension configurations and then the vibration signals are measured and identified by using ordinary acceleration sensors. Based on a time-frequency joint analysis technique, the experimental data is analyzed and processed to obtain the key vibration characteristic parameters of composite wing structure, such as the natural frequency and mode shapes, in a thermal-vibration coupled environment up to 1100°C. The experimental results provide an important basis for the dynamic performance analysis and safety design of composite wing structure under high-temperature thermal-vibration conditions