Transient Response of Coated Submersible Hull to Deep Underwater Explosion

2016 ◽  
Author(s):  
Caiyu Yin ◽  
Zeyu Jin ◽  
Yong Chen ◽  
Hongxing Hua
Keyword(s):  
Transient Response ◽  
Underwater Explosion ◽  
The Finite Element Method ◽  
Acceleration Response ◽  
One Dimensional ◽  
Combined Loads ◽  
Shock Mitigation ◽  
Deformation Velocity ◽  
Underwater Shock ◽  
Shock Resistance

Underwater explosion (UNDEX) can severely damage warships and submarines, so improving shock resistance ability of such weapons is of great importance. However, studies on enhancing shock resistance ability of submerged structures are limited. In this paper, the shock mitigation effects of cellular cladding coated on the submersible hull subjected to combined loads of hydrostatic pressure and shock wave are analyzed. First, one-dimensional analytical model is proposed to reveal the shock mitigation mechanism of cellular claddings. The pressure at fluid-structure interface and the thickness of cellular foam needed to fully dissipate shock energy are obtained. Then, the finite element method is employed to investigate the transient response of bare/coated submersible hull subjected to UNDEX. The results indicate that the cellular cladding coated on the pressure hull is very effective on reducing hull deformation, velocity and acceleration response if the cladding is not fully densified. Otherwise, the stress enhancement appears when the cladding is fully densified prematurely, which will weaken the shock mitigation effects. The research results are useful in designing surface shields for submersible hull so as to enhance its resistance to underwater shock damage.

Stationary and Transient Response of Cylindrical Shells Under Random Excitation

1988 ◽  
Vol 110 (2) ◽  
pp. 205-209
Author(s):  
A. V. Singh
Keyword(s):  
Transient Response ◽  
Random Vibration ◽  
Time History ◽  
Wide Band ◽  
Random Excitation ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
History Of ◽  
The Mean ◽  
Random Vibration Analysis

This paper presents the random vibration analysis of a simply supported cylindrical shell under a ring load which is uniform around the circumference. The time history of the excitation is assumed to be a stationary wide-band random process. The finite element method and the condition of symmetry along the length of the cylinder are used to calculate the natural frequencies and associated mode shapes. Maximum values of the mean square displacements and velocities occur at the point of application of the load. It is seen that the transient response of the shell under wide band stationary excitation is nonstationary in the initial stages and approaches the stationary solution for large value of time.

scholarly journals Finite Element Analysis of Thermoelastic Contact Stability

1994 ◽  
Vol 61 (4) ◽  
pp. 919-922 ◽  
Author(s):  
Taein Yeo ◽  
J. R. Barber
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Steady State ◽  
Eigenvalue Problem ◽  
Linear Perturbation ◽  
Dimensional System ◽  
The Finite Element Method ◽  
One Dimensional ◽  
Thermoelastic Contact ◽  
Element Method

When heat is conducted across an interface between two dissimilar materials, theimoelastic distortion affects the contact pressure distribution. The existence of a pressure-sensitive thermal contact resistance at the interface can cause such systems to be unstable in the steady-state. Stability analysis for thermoelastic contact has been conducted by linear perturbation methods for one-dimensional and simple two-dimensional geometries, but analytical solutions become very complicated for finite geometries. A method is therefore proposed in which the finite element method is used to reduce the stability problem to an eigenvalue problem. The linearity of the underlying perturbation problem enables us to conclude that solutions can be obtained in separated-variable form with exponential variation in time. This factor can therefore be removed from the governing equations and the finite element method is used to obtain a time-independent set of homogeneous equations in which the exponential growth rate appears as a linear parameter. We therefore obtain a linear eigenvalue problem and stability of the system requires that all the resulting eigenvalues should have negative real part. The method is discussed in application to the simple one-dimensional system of two contacting rods. The results show good agreement with previous analytical investigations and give additional information about the migration of eigenvalues in the complex plane as the steady-state heat flux is varied.

Channeling Flow and Solute Transport in a Single Fracture

2013 ◽  
Vol 316-317 ◽  
pp. 632-635
Author(s):  
Ye Fei Tan ◽  
Zhi Fang Zhou ◽  
Shi Qiang Wu ◽  
Xing Hua Xie ◽  
Bo Ning
Keyword(s):  
Finite Element Method ◽  
Drinking Water ◽  
Breakthrough Curve ◽  
Laboratory Experiments ◽  
Fractured Media ◽  
Single Fracture ◽  
The Finite Element Method ◽  
Dispersive Equation ◽  
One Dimensional ◽  
Channeling Flow

Groundwater in fractured media plays an important role in drinking water supply, and the understanding of its principle mechanisms is essential for securing the groundwater exploring and utilization. In this paper, a novel conceptual fracture model was presented on the basis of the reality of channeling flow in natural fractures and laboratory experiments were conducted for the purpose of getting a better understanding of the step-like breakthrough curve (BTC). Experimental results were fitted with convective dispersive equation (CDE) and compared with those of the finite element method (FEM) models. Results showed that the traditional one-dimensional CDE was invalid in the fitting of a step-like BTC and needed to be improved.

BATCH DOUGH VISCOSITY INFLUENCE ON FLOW-PRESSURE CHARACTERISTICS OF THE KNEADING MACHINE

2019 ◽  
Author(s):  
В.С. РУБАН ◽  
В.И. АЛЕШИН ◽  
Д.С. БЕЗУГЛЫЙ
Keyword(s):  
Batch Process ◽  
System Of Equations ◽  
Systems Of Equations ◽  
The Finite Element Method ◽  
Dimensional Model ◽  
Symmetric Form ◽  
Pressure Function ◽  
One Dimensional ◽  
Flow Pressure ◽  
Transport Problems

Рассмотрены уравнения баланса и концентрационных потоков, базирующихся на моделях, позволяющих анализировать одноименные модели реологии течения в канале шнека блока замеса тестомесильной машины. Анализ процесса транспортировки и замеса на основе одномерной модели выявил необходимость использования сигмоидальной функции коэффициента напоропроводности от давления. Переход от одномерных задач к многомерным задачам переноса связан с преобразованием систем уравнений к симметричному виду. Полученные системы уравнений после использования теоремы Грина могут быть решены методом конечных элементов. The balance equation and concentration flows based on the models which make it possible to analyze the eponymous models of flow rheology in the block screw channel in a dough mixing machine has been considered. The analysis of the transportation and batch process based on one-dimensional model proved the necessity to apply sigmoidal coefficient of pressure function. The transition from one-dimensional problems to multidimensional transport problems is associated with the transformation of systems of equations to a symmetric form. The resulting system of equations after using Green’s theorem can be solved by the finite element method.

Computer Simulation of Pulsed Laser Ablation for YBaCuO Superconducting Films

1990 ◽  
Vol 191 ◽  
Author(s):  
Toshiyuki Nakamiya ◽  
Kenji Ebihara ◽  
P. K. John ◽  
B. Y. Tong
Keyword(s):  
Thin Films ◽  
Excimer Laser ◽  
Laser Energy ◽  
Pulsed Laser ◽  
The Finite Element Method ◽  
High Tc ◽  
One Dimensional ◽  
Incident Laser Energy ◽  
Krf Excimer Laser ◽  
Pulsed Laser Irradiation

ABSTRACTThe dynamics of melting and ablation of high Tc YBa2Cu3O7-x superconducting thin films flashed by a pulsed KrF excimer laser(λ=248nm) or a pulsed Nd-YAG laser (λ =1.06μ m) were studied numerically. The fundamental model during a pulsed laser irradiation was a one-dimensional heat conduction equation. The finite element method was applied to solve the equation including the temperature dependence of the thermal conductivity of YBaCuO thin films. In addition, the microstructure of YBa2Cu3O7-x bulk(l.5mm thick) flashed by a pulsed XeCl excimer laser (λ =308nm) was investigated by scanning electron microscopy (SEM) in order to estimate the threshold incident laser energy density for surface melting and ablation. The good agreements between the numerical calculations and the experimental results were obtained.

Time Dependent Mathematical Model of Thermoregulation in Human Dermal Parts During Sarcopenia

2021 ◽  
Vol 4 (1) ◽  
pp. 41-53
Author(s):  
Dev Chandra Shrestha ◽  
Saraswati Acharya
Keyword(s):  
Body Weight ◽  
Muscle Mass ◽  
Vital Role ◽  
Time Dependent ◽  
The Finite Element Method ◽  
Bioheat Equation ◽  
One Dimensional ◽  
Metabolic Heat ◽  
Human Body Temperature ◽  
Weight Impact

Sarcopenia is an illness characterized by the loss of skeletal muscle mass, and its strength occurs in aging after 50 years. Muscle mass plays a vital role in body weight and metabolism. The loses in body weight impact reducing the basal metabolic rate (BMR). The BMR affects the human body temperature due to lower metabolic heat production during sarcopenia. The present study deals with time dependent temperature variation in human dermal parts during sarcopenia. The finite element method is used to solve a one-dimensional bioheat equation. In this model, the thickness of the epidermis, dermis layers, and the BMR of different aging, are estimated. The results show the nodal temperature of the epidermis and dermis layers increases due to reducing the thickness. Further, the subcutaneous nodal temperature slightly decreases due to the cause of BMR.

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