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Traditional suction bucket foundations incur high maintenance costs and are susceptible to corrosion, resulting in a diminished bearing capacity over prolonged service. The suction bucket foundation, constructed with a glass fibre-reinforced polymer (GFRP), introduces a novel approach to iteratively optimise conventional steel bucket foundations. In this study, three-dimensional finite element models of the GFRP bucket-soil interaction were established using the VUMAT subroutine, which incorporates the stress-strain damage relationship of GFRP materials. The mechanical response during installation was analyzed for different fibre-laying angles(A) and wall thicknesses(t) of the GFRP bucket, and the results were compared with those of a steel bucket. The results indicated increased circumferential stress, radial deformation, and out-of-roundness of the GFRP bucket as the fibre laying angle increased. Deformation and stress of the bucket skirt remained low at A of 0–45°. When A ≥ 60°, the matrix's damage area significantly increases, with the minimum damage occurring at 45°. For A ≤ 30°, it approaches the maximum radial deformation of an equivalent-sized steel suction bucket. As the wall thickness increased, the circumferential stress, radial deformation, and out-of-roundness of the GFRP bucket skirt gradually decreased. When the GFRP bucket t was four times that of the steel bucket, its radial deformation was approximately equal. • Provide new reference for the renewal and replacement of traditional suction buckets. • Critical control parameters for the response of GFRP suction bucket were determined. • GFRP material subroutine was written and applied. • Parameter coupling effect of GFRP suction bucket was considered and determined. [ABSTRACT FROM AUTHOR]

A robust integrated guidance and control (IGC) approach with L 2 gain performance is addressed for a hypersonic vehicle that operates in the dive phase and attacks a fixed target with a terminal angular constraint. A full-state hypersonic vehicle model that adopts the bank-to-turn technique is developed by combining relative motion equations, expressed in the line-of-sight coordinate system, between the vehicle and the target with rotational motion equations. For the proposed model in a strict feedback system, a novel IGC law with L 2 gain performance is developed based on the backstepping design procedure by recursively constructing Lyapunov functions of the model subsystems. Numerical simulations conducted for a six degrees of freedom model of the general hypersonic vehicle show that the proposed IGC law is robust against existing uncertainties and satisfies performance requirements. [ABSTRACT FROM AUTHOR]

An adaptive integrated guidance and control (IGC) scheme for hypersonic vehicle in dive phase is proposed in this paper. The three dimensional (3D) coupling relative dynamics and the explicit relations between line-of-sight (LOS) angles and the angle of attack and sideslip angle are described based on analytical aerodynamic models of the hypersonic vehicle. A coupling and full states IGC design model in strict feedback form is derived by combing the 3D relative dynamics and the equations of the rotational loop. In the deduction of the novel IGC scheme, the 3D impact angles and constraints of the normal overload, commands of Euler angles and three-channel body rates are accounted for. The solution of a ten-order, nonlinear, and uncertain IGC frame control system is converted into an output tuning problem. Pseudo-inputs associated with rotational motion are depicted using adaptive dynamic surface control theory. The desired control surface fin deflections are derived based on the block dynamic surface approach. The Lyapunov function consisted of dynamic surfaces, errors of the filters, and estimation errors is conducted, states of the IGC closed-loop system are proved to be uniformly ultimate bounded. Finally, the effectiveness and robustness of the adaptive IGC scheme are investigated and verified using six-degree-of-freedom (6DoF) nonlinear simulation studies. [ABSTRACT FROM AUTHOR]

The combination of fiber reinforcement method with microbially induced carbonate precipitation (MICP) for calcareous sand treatment has been widely concerned. In this study, the effects of initial relative density (D r =30%, 50%, 70%) and MICP treatment (N = 2, 4) on calcareous sand samples with different recycled shredded coconut coir (RSC) content (C = 0.00%, 0.20%, 0.40%, 0.60%) were investigated through a series of comparative tests. The results showed that the calcium carbonate content of the cemented samples was not significantly related to the RSC content, but was related to the relative density of the sand itself. The larger the relative density of the sand, the smaller the porosity, which is not conducive to the generation of calcium carbonate. The maximum shear modulus and permeability coefficient of the samples were positively related to the N and D r , and exponentially related to the calcium carbonate content. The treated calcareous sand samples after N = 4 showed brittle failure characteristics, and the addition of RSC improved this result. For the peak stress of samples, the optimum amount of RSC was about 0.4% under different conditions. Scanning electron microscopy of shear-failure samples showed that calcium carbonate crystals could bind the sand and RSC and increase the contact area between them. [ABSTRACT FROM AUTHOR]