The method of determining the dynamic characteristics of traffic

 

The invention relates to shipbuilding and relates to a technology for dynamic characteristics of ship traffic at the design stage. The method of determining the dynamic characteristics of ship motion in waves in a towing tank basin consists in using geometrically similar, but not dynamically similar models ship with known mass-inertia characteristics. Characteristics of the model and its kinematic responses during tests determine the impulse force Smmodel of the ship and the impulse of the moment of force Mm. The received pulses are translated using the geometrical similarity of the impulse force Scfor the vessel and the impulse of the moment of force Mwithfor the vessel, respectively, by the formulas Sc=m3,5Smand Mwith=m4,5Mmwhere m is the scale of the full-scale vessel in relation to its model. Then to determine the dynamic responses of the vessel consider oscillatory system of masses, stiffness and damper vessel, relevant fluctuations, and by calculating this system the pulses of force and moment forces determine all necessary reaction vessel when going on a rampage. The technical result of the invention lies in the first of which was determined only static characteristics and to simplify the determination of the dynamic characteristics of the motion of the vessel by creating special exceptions dynamically similar (but simplified) models and their testing. 3 Il.

The invention relates to shipbuilding and applies the dynamic characteristics of traffic at the design stage. Methods of determining the characteristics of resistance and seaworthiness of ships, which are also linear acceleration (overload) and pitching angles described in the literature, for example in open strings, K. F., fundamentals of hydro. - M, WiMo, 1961, S. 438-454, 546-552; Zaitsev, N. A., Moskalik A. I. Domestic hydrofoils. - Leningrad: Sudostroenie, 1967, S. 92-99; fundamentals of theory of the hovercraft. - Leningrad : Sudostroenie, 1970, S. 446-448, and are used in the design. These methods consist in the manufacture of dynamically similar models of a vessel in a certain scale, the supply of this model measuring system for recording resistance, vertical displacement and pitch angle, and test these models in the model tank. Methods of attaching the model to the trucks towing tank leads to complexity of software similarity model for the masses and moments of inertia due to the inclusion of a dynamic system is a high-speed vessels with automatic motion control and accelerating or decreasing resistance. In these cases, to obtain dynamic similarity is not possible, and the model with unloading by weight is used only to determine the static characteristics of the movement: the movement resistance force, lifting force, landing (precipitation) and trim angle. Therefore, to determine the dynamic characteristics of motion - acceleration and pitching angles - made another model with the highest possible similarity of mass and moments of inertia (but without the various devices), which are being tested by towing behind the nose in the water tank pool or open water behind a boat. This model enables us to determine the dynamic characteristics with accuracy that depends on the fidelity of the masses and moments of inertia and inaccuracies introduced by the tow behind the nose (instead of application of the forces, simulating rod and attached to the propellers). Thus, one model determine the static characteristics of motion, and other dynamic characteristics. Towed model to ensure similar mass and moments of inertia have to perform a simplified without simulated devices villages dynamic characteristics of the motion. Dynamic characteristics of motion necessary to assess the capability of the designed vessel for passengers, being (health) crew, cargo, using weapons, and for determining external loads for strength calculations. Therefore, inadequate definition of dynamic characteristics leads to an incorrect assessment of the design of the ship and negative consequences of use. Current improvements relating to the testing of ship models in a towing tank basin, mainly aimed at the compensation of the excess mass model and device attachment.

For example, A. C. 1541109 - provides for compensation excess weight by creating electromagnetic forces, A. S. 1740240 - provides for the creation of damping forces in the vertical oscillations of the model, A. S. 140787 - provides for compensation of the weight of the pylon (suspension), A. S. 1579841 to determine the impact force model is used in two parts connected by an elastic element, which allows to estimate the dynamic impact force in the fore part.

All of the above methods do not help to solve the main task is to determine the dynamic characteristics of motion models is gaining development opportunities of the dynamic characteristics of the motion of the vessel, on the same models that are used to determine the static characteristics.

The technical result from use of the present invention will be to: 1. Precise determination of the dynamic characteristics of the motion.

2. Dynamic characteristics will be determined on models that are defined only static features.

3. There is no need to create a special dynamically similar (but simplified) models and their testing.

4. The obtained results can be used to determine the external loads for strength calculations and exclude the creation and testing of ProgOptions model.

This result is achieved in that a geometrically similar model, not like the mass and moments of inertia is tested in the model tank, with varying degrees of excitement. Before testing for the model is determined experimentally weight with all devices suspension models participating in vertical movement together with the model, and the mass moment of inertia of the model relative to the hinge mounting of the model to the suspension (mm, Im). When installing model (suspension) on the cart model is discharged to the calculated mass of any used the e and hull Pbeats= f(Vc,,,hin,...) and does not depend on the initial moment from masculinizing characteristics.

The reaction of the same model on the kick, and acceleration,the trim angle, etc. depends on the impact force and mass. For high-speed vessels [for vessels with a large displacement in the small excitement] the time to collision is less than the half period of the first tone vertical bending vibrations and in this case, the impact force can be replaced by the momentum of the blowand in relation to the angular movements of the pulse timeThese pulses are associated with the experimental values of the response of the model formula Sm= mmoZ
here mm- mass model;
o- circular frequency of oscillations of the model under the action of the pulse strength;
Z - maximum vertical displacement of the model.

A similar formula is obtained for the impulse of the moment

here Im- model inertia mass model;
- maximum trim angle;
- the a and then the value of the pulse power and torque for the vessel will be:
Sc=m3,5Sm
Mwith=m4,5Mm
where m is the scale field of the vessel in relation to the model.

To determine the dynamic responses of full-scale ship is considered oscillatory system consisting of mass, stiffness and dampers vertical oscillations and brought to him the corner and, if necessary, and bending oscillations of the first tone.

By calculating this system on impulse action force (or impulse force is equivalent to the impulse of the moment) are all necessary reaction vessel when going on a rampage.

The proposed method is illustrated by drawings, where Fig.1 shows the typical suspension model truck towing tank of Fig.2 - record type when testing the model on a rampage in Fig.3 - schematic diagram of the dynamic model of the ship.

Model 1 is equipped with all kinds of devices, such as SAUD, a system for reducing the resistance of the discharge system and by means of the hinge 2 is attached to the pylon 3, which can perform only vertical movement due to the movement in the guide 4, to the top of the pylon is attached to the device for static compensation excess weight models and pylon 5 (which may be of a different design).

In Fig.3 shows the dynamic system of the ship:
where 10 is the mass of the ship;
11 - the equivalent stiffness of the vessel at a vertical oscillations;
12 - the damping of the vessel at a vertical oscillations;
13, 14, 15 - the same vessel characteristics, given to the cross-section, which has a shock;
16, 17, 18 - the same characteristics, but when the vibrations of the ship I tone Flexural vibrations;
19 - momentum forces acting on the vessel.

Thus, when using the proposed method it is possible to obtain the dynamic characteristics of ship motion in waves when tested geometrically similar, but not similar in mass-inertial characteristics of the model in the model tank and use the results to assess seaworthiness of the vessel and its strength.


Claims

The method of determining the dynamic characteristics of ship motion in waves in a towing tank basin using geometrically similar, but dynamically dissimilar model of a vessel with known mass-inertial characteristics, characterized in that paragraph and the ship and the impulse of the moment of force Mmreceived pulses are translated using the geometrical similarity of the impulse force Scfor the vessel and the impulse of the moment of force Mwithfor the vessel respectively by formulas

Sc=m3,5Sm

and Mwith=m4,5Mm,

where m is the scale field of the vessel in relation to its model,

and then to determine the dynamic responses of the vessel consider oscillatory system of masses, stiffness and damper vessel, relevant fluctuations, and by calculating this system the pulses of force and moment forces determine all necessary reaction vessel when going on a rampage.

 

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SUBSTANCE: proposed device includes towing trolley with frame rigidly secured on it; this frame is provided with bar which is connected with model through dynamometers and bearing plate. Dynamometers form three-support force-measuring system; they are provided in each support in form of two interconnected elastic members; one elastic member is made in form of five-rod member provided with longitudinal and lateral force sensors; it is located between two flanges. Second elastic member of dynamometer is made in form of membrane-type elastic member whose membrane is located between rigid rim and rigid central part of this member provided with threaded rod with elastic hinge mounted over vertical axis perpendicularly relative to membrane. Membrane, rim and rigid central part with threaded rod and elastic hinge are made integral. Rim of membrane elastic members is rigidly connected with one of flanges of five-rod elastic member in such way that threaded rod is located along vertical axis of support and is rigidly connected via elastic hinge with bearing plate secured on model. Membrane is provided with resistance strain gages forming vertical force measuring bridge. Second flange of each five-rod member is connected with additional bearing plate secured on bar.

EFFECT: enhanced accuracy of measuring forces and moments.

3 dwg

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