An improved time integration scheme based on uniform cubic B-splines and its application in structural dynamics

A time integration algorithm for structural dynamic analysis is proposed by uniform cubic B-spline functions. The proposed algorithm is successfully used to solve the dynamic response of a single degree of freedom （SDOF） system, and then is generalized for a multiple-degree of freedom （MDOF） system. Stability analysis shows that, with an adjustable algorithmic parameter, the proposed method can achieve both conditional and unconditional stabilities. Validity of the method is shown with four numerical simulations. Comparison between the proposed method and other methods shows that the proposed method possesses high computation accuracy and desirable computation efficiency.

High-entropy(La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Yb_(0.2))_(2)(Zr_(0.75)Ce_(0.25))_(2)O_(7)thermal barrier coating material with significantly enhanced fracture toughness

Poor fracture toughness leads to premature failure of La_(2)(Zr_(0.75)Ce_(0.25))_(2)O_(7)(LCZ)ther-mal barrier coatings in an elevated temperature service environment.A novel coating material,namely(La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Yb_(0.2))_(2)(Zr_(0.75)Ce_(0.25))_(2)O_(7)(LNSGY)based on the high-entropy con-cept,was successfully fabricated by solid-state sintering.The microstructure of LCZ and LNSGY was investigated by X-Ray Diffraction(XRD),Raman Spectrometer(RS),Transmission Electronic Microscopy(TEM)and Scanning Electron Microscopy(SEM).The fracture toughness of the LCZ and LNSGY ceramics was evaluated.The LNSGY has excellent high-temperature phase stability,and the grain size of LNSGY ceramic is smaller than that of LCZ ceramic at an elevated temper-ature due to the sluggish diffusion effect.Compared with LCZ(fracture toughness is(1.4±0.1)MPa·m^(1/2)),the fracture toughness of LNSGY is significantly enhanced(fracture toughness is(2.0±0.3)MPa·m^(1/2)).Therefore,the LNSGY can be a promising advanced thermal barrier coat-ing material in the future.

Lightweight quasi-layered elastic fibrous porous ceramics with high compressive stress and low thermal conductivity

Fibrous porous ceramics are attractive for use as thermal insulation materials.However,the intrinsic brit-tleness of rigid materials has remained challenging and severely restricts their applications.Here,we demonstrated a facile method for fabricating elastic fibrous porous ceramics(EFPCs)with high com-pressive strength and low thermal conductivity through ordinary press filtration and subsequent heat treatment.The quasi-layered structure and the well-bonded bridging fibers between layers are the key points for the elasticity of EFPCs.The advanced EFPCs exhibited low density(∼0.126 g cm^(−3)),high com-pressive stress(∼0.356 MPa),and low thermal conductivity(∼0.026 W m^(−1) K^(−1)).Compared with rigid porous fibrous materials,the EFPCs had deformability and excellent shape recovery.In contrast to flexible materials,the EFPCs possessed high compressive stress,thus endowing them with good resistance to de-formation.The emergence of this fascinating material may provide new insights for candidate materials in thermal insulation and other fields.

High-entropy rare-earth zirconate ceramics with low thermal conductivity for advanced thermal-barrier coatings

The high-entropy rare-earth zirconate((La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Yb_(0.2))_(2)Zr_(2)O_(7),5RE_(2)Zr_(2)O_(7)HEREZs)ceramics were successfully prepared by a new high-speed positive grinding strategy combined with solid-state reaction method.The microstructure,crystal structure,phase composition,and thermophysical and mechanical properties of the samples were systematically investigated through various methods.Results indicate that the samples have a single-phase defect fluorite-type crystal structure with excellent high-temperature thermal stability.The as-prepared samples also demonstrate low thermal conductivity(0.9–1.72 W·m^(−1)·K^(−1)at 273–1273 K)and high coefficient of thermal expansion(CTE,10.9×10^(−6)K^(−1)at 1273 K),as well as outstanding mechanical properties including large Young’s modulus(E=186–257 GPa)and high fracture toughness(KIC).Furthermore,the formation possibility of the as-prepared samples was verified through the first-principles calculations,which suggested the feasibility to form the 5RE_(2)Zr_(2)O_(7)HE-REZs in the thermodynamic direction.Therefore,in view of the excellent multifunctional properties exhibited by the as-prepared 5RE_(2)Zr_(2)O_(7)HE-REZs,they have great potential applications in next-generation thermal-barrier coatings(TBCs).