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Umbilical cables are integral components of subsea production systems. In this study, the buckling failure of umbilical cable with damaged sheath under bending and compression loads was investigated. A finite element (FE) model of an umbilical cable with a damaged sheath was established using software ANSYS. The influences of the location and area of sheath defects on birdcage buckling and the impacts of the exposed area of the armor wire and the applied bending radius on the buckling mode were analyzed. The results indicate that the exposed area of the armor wire determines the buckling mode and critical buckling load. An increase in the exposed area triggered a transition from lateral buckling to birdcage buckling. Lateral buckling occurred when the exposed area was below 6%, birdcage buckling occurred when it exceeded 10%, and both types of buckling occurred when the exposed area was 8%. Furthermore, when different bending radii were applied, such transitions consistently occurred when the exposed area was 8%. This study elucidated the buckling mechanism of armor wires by considering the combined loads and damaged sheaths, thus contributing to the prevention of buckling failure. • The buckling mechanism of umbilical cable with damaged sheath under bending and compression loads was elaborated. • The influence of the location and area of sheath defect on the birdcage buckling was analyzed. • The influence of the exposed area of the armor wire and bending radius on the buckling mode was discussed. [ABSTRACT FROM AUTHOR]

In order to analyze the mechanical properties of a new type of retrievable vena cava filter, the Denali and Aeginsy retrievable filters are selected, and the in vivo and in vitro mechanical properties of the three types of retrievable vena cava filters are compared. The nonlinear deformation process of the filter which is pressed into the transport sheath, flicked and released into the vascular vessel is simulated by using the finite element method, and the mechanical behaviors of the filter and the blood vessel wall are analyzed. During the crimping process, the elastic strain peak value of the filter wall increases with increasing amount of grip. The maximum elastic strain peak value of the three filters is less than 8%, and the safety factor is greater than 2, which meets the strength requirement. Equivalent stress and strain on the vascular wall decreases along the direction of blood flow after the filter is opened. The peak value of equivalent stress and strain on the vascular wall corresponding to Aegisy filter is the largest, and the impact on the vascular wall is the largest. The total displacement of the three filters under the action of thrombus and blood fluids is not more than 80 μ m. The impact of the new filter on the vascular wall is smaller than that of Aegisy filter, and the total displacement after implantation is smaller than that of Denali filter. The results are valuable for the evaluation and clinical application of the new vena cava filter. [ABSTRACT FROM AUTHOR]

In order to analyze the mechanical properties of a new type of retrievable vena cava filter, the Denali and Aeginsy retrievable filters are selected, and the in vivo and in vitro mechanical properties of the three types of retrievable vena cava filters are compared. The nonlinear deformation process of the filter which is pressed into the transport sheath, flicked and released into the vascular vessel is simulated by using the finite element method, and the mechanical behaviors of the filter and the blood vessel wall are analyzed. During the crimping process, the elastic strain peak value of the filter wall increases with increasing amount of grip. The maximum elastic strain peak value of the three filters is less than 8%, and the safety factor is greater than 2, which meets the strength requirement. Equivalent stress and strain on the vascular wall decreases along the direction of blood flow after the filter is opened. The peak value of equivalent stress and strain on the vascular wall corresponding to Aegisy filter is the largest, and the impact on the vascular wall is the largest. The total displacement of the three filters under the action of thrombus and blood fluids is not more than 80 μ m. The impact of the new filter on the vascular wall is smaller than that of Aegisy filter, and the total displacement after implantation is smaller than that of Denali filter. The results are valuable for the evaluation and clinical application of the new vena cava filter. [ABSTRACT FROM AUTHOR]

Microneedles (MNs) are particularly attractive for transdermal administration because of the improved safety, patient compliance and convenience. Dissolving MNs could provide rapid transdermal delivery, but with relatively low mechanical strength and almost no sustainability. On the other hand, hydrogel MNs are complicated to fabricate and have risk concerns. Herein, we developed a biodegradable MNs array composed of biocompatible silk fibroin and poly(vinyl alcohol) to overcome these limitations. Finite element analysis was employed for parameter optimization. The MNs array fabricated by the optimal parameters and material displayed sufficient mechanical strength to disrupt stratum corneum and formed microchannels for transdermal delivery. Dual-release profile was observed in the MNs array, with rapid release in the beginning, and prolonged release afterward. This release behavior fits Weibull release model and is favorable for topical application. The initial immediate release can quickly deliver active compounds to reach the therapeutic effective concentration and facilitate skin penetration, and the sustained release may supply the skin with active compounds over a prolonged period. This biodegradable MNs array is easy to fabricate, mechanically robust, could eliminate safety concerns, and provide the sustainability and advantage for large-scale production. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper will discuss the failure mechanism of high field pulsed magnets based on a failed pulsed magnet of 85 T. Firstly, the stress failure possibility is analyzed by an ANSYS-ACP finite element model. The results show that the stress failure risk is low. Then a comprehensive model including both stress failure and structural buckling is proposed and discussed. It is found that the structural buckling and stress failure would co-exist and interact with each other. The model predicts the pulsed magnet suffered from stress failure after structural buckling and finally collapsed at 79 T. The consistency of the theoretical results with that in experiments show the validity of the comprehensive model. • First comprehensive analysis including stress failure and structure buckling of pulsed magnets under biaxial Lorentz force body. • It is a typical interdisciplinary and deep study of electromagnetic devices. • The simulation results were consistent with the experimental results. • The results show that the structural buckling and over-stressing failure would co-exist in pulsed magnets. • The bad wettability of Zylon fiber by epoxy resin maybe an important factor of the buckling and failure of pulsed magnets, which will guide the improvement of pulsed magnet technology. [ABSTRACT FROM AUTHOR]