Aerospace and military defense fields are posing higher requirement on the lightweight feature of structures. Subject of this study is the Aluminum Alloy 5A02 /CFRTP (Carbon Fiber Reinforced Thermo-Plastic) laminates. In the paper, aluminum alloy was anodized, compression molding and 3D printing were adopted to prepare Carbon Reinforced Aluminum Laminates (CARALL) with two different structures: the solid core structure and the honeycomb structure, and the prepared specimens were then tested for mechanical properties via tensile test and three-point bending test, and compared with the performance of the conventional aluminum alloy. The results show that under the condition of a same thickness, the tensile strength of CARALL specimens with the molded solid core structure and the 3D printed honeycomb structure reaches 256Mpa and 186MPa, respectively, which is 85.5% and 34.8% higher than that of the tensile strength of Al 5A02; under different bending modes, the maximum bending strength is 682Mpa and 525Mpa, respectively, which is 62.4% and 25.5% higher than that of Al 5A02. When the specimens are subject to tensile force, the separation of the metal layer and the fiber layer is the primary failure form, the fiber layer fractures, and the metal layer exhibits the necking phenomenon as the metal fibers are being pulled out. During the bending process, for different bending forms, there’re great differences in the bending strength of CARALL specimens prepared by the same method, the failure modes of the specimens vary greatly as well, and this is determined by the tensile strength of the carbon fiber layer and the tensile strength of AL 5A02. Enhancing the bonding strength between the metal layer and the fiber layer can improve the mechanical properties of CARALL. These research findings can provide a reference for the lightweight design of metals and Fiber Metal Laminates (FMLs).

ABSTRACT With its excellent fatigue performance and high damage tolerance and other irreplaceable advantages, FMLs have gradually increased the demand in aerospace, rail transit, ship and other fields, and have put forward higher requirements for the speed and accuracy of its performance test and index evaluation. In this paper, the methods of performance test, analysis and index evaluation of FMLs are introduced from three aspects with carbon fiber and composite materials, mechanical properties and numerical simulation technology, details the common test methods, the latest technology and progress, and analyzes their advantages and disadvantages, so as to provide direction and reference for the performance test method and index evaluation of FMLs. Finally, the main development directions of the current performance testing methods and index evaluation of FMLs are briefly discussed. aerospace transit fields paper materials progress disadvantages Finally discussed

ABSTRACT Curing is a critical process in the compression molding of carbon fiber reinforced polymer (CFRP). It directly bears on the quality of the molded products. Based on the curing theory of resin-based polymers, a thermo-mechanical-chemical multi-field coupling model for CFRP curing in the form of thermal-chemical subprocess, matrix flow-compaction sub-process and residual stress-deformation subprocess, and sets up its data exchange and mutual call relationship. Considering the thermal physics and chemical properties of composites change with temperatures, the authors introduced the thermal viscosity stiffness coefficient and took AS4/3501CFRP molded laminate as an example, and carried out a multi-field coupling simulation of the CFRP curing through compression molding, using the finite-element software COMSOL. The proposed model was proved correct through calculation of an example in the literature. Further, the CFRP curing mechanism was revealed through a detailed analysis on the evolution of temperature, curing degree, stress and strain of the CFRP curing through compression molding. The results show that the large internal temperature gradient during the compression molding of laminates is the main reason for the residual stress of materials and the deformation of laminate. Finally, an AS4/3501CFRP molded laminate was prepared, and its temperature field was monitored by fiber Bragg grating (FBG) transducers. The temperature evolution law of the material was consistent with the finite element simulation results, which demonstrate the correctness of the simulation.

ABSTRACT This paper attempts to solve the turbine failures reported by a hydropower station, namely, the violent vibration in the runner region under a special working condition and the blade cracking on the outlet edge near the lower ring. For this purpose, the entire flow channel of the turbine was simulated by computational fluid dynamics (CFD) on ANSYS, and the runner strength and mode of shaft assembly system (SAS) were computed by the liquid-solid coupling algorithm. The calculation results show that severe low (negative) pressure appeared on the outlet edge near the lower ring, excess stress was observed in that area, and the resonance occurred as the fifth and sixth order natural frequencies of the SAS were the same with the rotation frequencies of the blade. On this basis, the original blade was modified repeatedly. Through the modification, the flow field distribution in the runner region and the blade strength were both greatly improved, and the SAS natural frequencies were kept away from the various external excitation frequencies, laying a solid basis for the safe and stable operation of the turbine.

ABSTRACT As high-end equipment requires a higher and higher sealing effect, sealing forms such as packing seals expose problems such as considerable wear and high heat generated by friction. Based on the theoretical analysis of the instability at the liquid-liquid interface and the pressure resistance of the seal structure, considering the rotating speed of the rotating shaft, this paper reconstructs the formula for calculating the pressure resistance value of the seal structure. On this basis, a magnetic fluid seal structure is designed for a large horizontal shaft diameter in liquid. Based on the magnetic field analysis software Maxwell, the magnetic field of the magnetic fluid seal is analyzed, and the mapping relationship between the different tooth widths of the pole teeth, the size of the permanent magnet, and the difference in the magnetic induction intensity of the seal gap is obtained. Built in the ring seal test system, the pressure test of the horizontal large shaft diameter seal structure under different rotating speeds was carried out to verify the effectiveness of the seal structure. The results have specific theoretical research significance and engineering application value for designing and applying magnetic fluid seal structures. highend end effect friction liquidliquid liquid basis Maxwell analyzed teeth magnet obtained system structures