A B S T R A C T A numerical and experimental investigation was conducted to determine the effect of interference-fit size on damage behaviour of bolted single-lap carbon fibre-reinforced plastic/Ti alloy composite structure. Three-dimensional finite element analysis (FEA) was conducted for interference-fit bolt installation process considering the friction coefficient and nonlinear shear stress-strain relationship, and damage sub-routine was used to predict composite progressive failure region and failure type in single-lap bolted-joints. Experiments involving three interference-fit sizes of 0.4%, 2.1% and 3.0% were designed to verify the FEA. In addition, micro-analysis results show that damage type during interference-fit bolt inserting process predicted by FEA was consistent with experimental results. Various types of micro-scale damage around the hole after interference bolt installation were analysed and characterised, and the effects of interference-fit size on structure strength were analysed in view of micro-scale damage. An appropriate interference-fit size can prompt the carbon fibre-reinforced plastic hole to become 'brush-like' and exhibit 'soften' and 'buffering' effect that improves the bearing capacity. In this paper, interference fit of 2.1% exhibits the maximum bearing damage strength.Keywords 3-D finite element analysis; bolted joint; interference fit; micro-damage; mixed mode failure. N O M E N C L A T U R Ed = specimen hole diameter D = diameter of the bolt E = short-edge distance to bolt diameter E i = elastic modulus in the i-direction F CFRP = pressing force when HI-LOK shank penetrates into CFRP layer F Ti = pressing force when HI-LOK shank penetrates into Ti alloy layer G = shear modulus H = plate thickness I = interference fit per cent L = long-edge distance to bolt diameter P CFRP = extrusion force of CFRP layer P ′ CFRP = maximum extrusion force of CFRP layer Q = stiffness matrix W = plate width α = nonlinear material constant parameter ε i = main strain in the i-direction μ = friction coefficient of hole wall for CFRP and Ti alloy σ i = main stress in the i-direction ν i = Poisson's ratio in the i-direction Correspondence: K. Zhang.

Nitinol superelastic stents have been widely used to treat the vascular stenosis due to its excellent mechanical behavior and biocompatibility. However, there exist conflicts between the functional properties and mechanical properties of the stent. An optimization method has been employed to deal with the conflictions with the consideration of the whole implementation process of the stent in this paper. A straight vascular with tumor inside is considered. A commonly used NiTinol superleastic stent with diamond shape strut is employed. The vascular wall tissue and stenotic plaque are also treated as hyperelastic materials. Softwares Isight, ABAQUS and Solidworks are utilized to perform the optimization job. It can be seen that the stresses are high at the areas around the fillets of the stent due to the stress concentration from a primary analysis. Therefore, the two fillets radius, thickness and radius of the stent are chosen as four optimization variables. The optimization object is to decrease the maximum stress of stent and increase the displacement of the plaque. After the optimization, the maximum stress can be decreased by 8.2 %, which implies that the stent's work life can be increased. The stenosis of the blood vessel can be decreased from 56 % to 40.0 %.

To control secondary flow effects and enhance the aerodynamic performance of the compressor, the flow control effects of the flow suction at the endwall with different circumferential positions and at the blade tip were numerically investigated in the cantilever stator of an axial single-stage transonic compressor. The main purpose was to gain a better understanding of the application of boundary layer suction and the associated control mechanisms in the cantilever stator. The studies show that the optimal position of the endwall suction slot should be located up the stator blade, in terms of the leakage flow structures and the blade tip unloading effect. In addition, the flow control effects of the suction at the blade tip on leakage flow upstream is better than that of the endwall flow suction with the same structure. Further, the studies of compressor aerodynamic performance curves illustrate that the efficiency and pressure ratio is increased by 0.34% and 1.09% at the peak efficiency point, and are increased by 0.39% and 0.14% at the near stall point, respectively.