Prediction of hydrodynamic loads during water impact is of great significance in the structural design of flying vehicles. Also the importance of the slam FORCE of waves on the members of offshore structures cannot be overemphasized. No theoretical tool is available to handle this complicated phenomenon exactly and the experimental procedures in the laboratory are both time-consuming and expensive.In this paper, a computer program based on the VOF method is applied to evaluate the water impact outcome in a real situation. To asses the capabilities of the CFD code, two classical problems including water impact of a wedge and a circular cylinder traveling at constant speeds are studied. In a real situation the descend velocity is decreased by the impact loads known as "deceleration effect". This change in speed is taken into account in an iterative procedure and the flow field around the base of a WIG craft is computed. All flow field computations in this study include the effects of viscosity, turbulence, gravity and surface tension. The comparison of results with experimental data shows the efficiency and correctness of this straightforward iterative method.

The suitable design of the keel and skis is of great significance in reduction of impact load on the bottom surface of the flying boats and in hydrodynamic stability during take-off and landing. No theoretical tools are available to handle the effects of viscosity, gravity, and surface tension. Also, the experimental procedures in the laboratory are both time-consuming and expensive. In this paper, numerical simulation of two-phase flow in the water impact problem of a WIG with VOF method and finite volume methods are taken into account and the effect of changing the dead-rise angle on the SLAMMING FORCE is investigated. An algebraic relation based on the dimensionless parameters for the maximum slam FORCE is developed. This is a new step towards choosing the optimum dead-rise angle of the keel and skis of flying boats, faster and easier and decreases the cost of numerical calculations.

In this research, a numerical simulation of a symmetric impact of a 2-D wedge, considering rigid body dynamic equations of motion in two-phase flow is presented. The two-phase flow around the wedge is solved based on finite volume method and Volume Of Fluid (VOF) scheme. The dynamic mesh model is used to simulate dynamic motion of the wedge, thereby; the effects of different dynamic meshes in both structured and unstructured meshes in simulating symmetric water impact phenomenon are investigated. Moreover, the effects of flow turbulence and fluid compressibility at the moment of water impact are studied. Also, the effects of different deadrise angles and body mass on the SLAMMING FORCE are investigated. At last, the impact problem of a wedge with constant velocity is solved and the results are compared with those calculated by considering dynamic equations of the motion.

In this article, rigid wedge water entry problem under different conditions is evaluated using numerical scheme Rigid wedge water entry continues to be one of the fundamental issues raised in the hydrodynamics studies and is known as a reference for the study of SLAMMING phenomena. The exact calculation of the pressure caused by the SLAMMING phenomenon can be used to analyze the appropriate structural analysis of the ships. In the current study, important variables such as speed and fluid pressure are investigated using computational fluid dynamics method based on the open source Open FOAM code by numerical solution of the governing equations of tow phase fluid. In order to verify the simulation results obtained from this research, Tthe values of the maximum pressure and the location and exact time of its occurrence and also pressure coefficient distribution at the impact region have been compared by experimental results of other studies. These investigations have been utilized at different impact velocities and angles. By comparing the numerical results and experimental values, an error was found in the range of 2% to 9%. In addition, variables affecting the pressure applied to the wedge such as water entry velocity and different deadrise angles have been studied.

Background and Aim: Superelasticity refers to the same amount of FORCE exerted by an ideal archwire independent of the degree of activation. Clinical findings show that in most of situations these materials do not fulfill the expected properties. The aim of this study was to evaluate the bending properties of some of these archwires.Materials and Methods: In this experimental research eight specimens of each of the round wires with 0.14, 0.16 and 0.018 inch sizes of FORCE I, rematitan lite and superelastic G & H types were tested. These wires were subjected to a three point bending test by DARTEC machine. Data were tested by ANOVA and Duncan tests at 0.05 level of significance. Results: All of these materials showed superelastic properties or at least superelastic tendencies. More pronounced superelastic properties were observed in thicker wires. However, their FORCE level of plateau for 0.014 inch rematitan lite wires the end of the plateau was observed when the wire was displaced at least 0.6 mm.Conclusion: In all of these wires, the FORCE level of plateau was higher than the optimal FORCE required for tipping movements.

Optimisation of stacking sequence for composite plates under SLAMMING impact loads using genetic algorithm method is studied in this paper. For this purpose, SLAMMING load is assumed to have a uniform distribution with a triangular-pulse type of intensity function. In order to perform optimisation based on the genetic algorithm method, a special code is written in MATLAB software environment. The prepared code is so coupled with the commercial software ANSYS that in each step of optimisation, it could analyse the composite plate under study and calculate the central deflection. After validation, different cases of stacking sequence optimisation are investigated for a variety of composite plates. The investigations include symmetric as well as anti-symmetric conditions of stacking sequence. Results obtained from these analyses reveal the fact that the adopted approach based on genetic algorithm is highly capable for performing such optimisations.

SLAMMING is usually a combination of different loads on the vessel hull and is one of the main causes of failure and failure in the structure of vessels. The influence of SLAMMING compared to other loads from the sea waves is so significant that in some cases the vessels are severely damaged locally by structural damages. Failure to accurately estimate the influence of SLAMMING will result in improper design of the ship's structure, thereby weakening the ship's safety. In trimaran vessels, the fluid FORCE applied to the side hulls is transmitted to the main hull by a transverse deck. As a result, one of the most important parts of the structure of this vessel is the transverse deck structure, the design of which requires the calculation of the incoming wave FORCEs. In this paper, the phenomenon of SLAMMING on the side hull and the transverse deck of the trimaran has been examined experimentally by measuring the pressure created by the collision of the model of trimaran vessel with the water surface. The results showed that in bottom regions of trimaran vessels, the pressure on bottom is increased going from stem towards stern. Also, the pressure on the transverse deck increases from the main hull to the side hulls. In the position of the shaft axis and the shaft post at the main hull, owing to the earlier impact of the stern of the main hull with the water surface compared to the side hulls, the pressure is higher than the other positions.

SLAMMING loads are important in the structural design of high speed vessels. SLAMMING can cause global and local effects on the ship structure. Here global effect of SLAMMING (bow flare water impact) means whipping considering hydroelasticity investigated. Considering ideal, non-viscous and non-compressible fluid, bow flare impact loads is developed after determination Bow flare impact FORCEs, with considering of proper beam model and exerting condition due to hydroelasticity, new form of beam deflection model is derived. In deriving of the beam deflection equation, hydroelasticity is considered, thus solving beam equation leads to hydroelastic analysis of bow flare SLAMMING. Finite difference method is used for solving this equation. In order to validate the computation of results, the third party software ANSYS is used. The ship hull girder is represented by a uniform onedimensional beam that is supported by a uniform elastic foundation. Time depending load is applied as a pressure on end beam and deflection is calculated.