CN117763993A - Calculation method for petal-shaped tearing hole of wall plate of liquid filling box body triggered by water hammer load - Google Patents
Calculation method for petal-shaped tearing hole of wall plate of liquid filling box body triggered by water hammer load Download PDFInfo
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Abstract
The invention belongs to a calculation method for tearing and breaking holes of a wall plate of a liquid filling tank triggered by impact, in particular to a calculation method for petal-shaped tearing and breaking holes of a wall plate of a liquid filling tank triggered by water hammer load, belonging to the technical field of oil tank damage performance test; the invention provides a method capable of calculating the size and shape of a petal-shaped broken hole of an oil tank wallboard caused by high-speed penetration by combining the fundamental principles of fluid dynamics, fluid-solid coupling and solid dynamics, and the method converts the solving problem of the size and shape of the petal-shaped broken hole into the solving problem of a differential equation, can efficiently calculate a quantitative result according to the differential equation and is used for guiding the design of the anti-destruction capability of an aircraft oil tank for resisting the impact of the high-speed penetration.
Description
Technical Field
The invention belongs to a calculation method for tearing and breaking holes of a wall plate of a liquid filling tank triggered by impact, in particular to a calculation method for petal-shaped tearing and breaking holes of a wall plate of a liquid filling tank triggered by water hammer load, and belongs to the technical field of oil tank damage performance test.
Background
The water hammer effect usually occurs when a liquid filled container is impacted by a high-speed penetration body (projectile or fragment), and in the penetration process, the kinetic energy of the penetration body is transferred to the liquid in the container, so that a strong pressure load is generated in the liquid, and meanwhile, the phenomena of cavities, high pressure and the like are accompanied, and then the pressure load acts on the container, so that the container is seriously damaged. Such pressure loads are also referred to as water hammer loads. Most of existing aircraft are used as fuel tanks for storing fuel, and when the fuel tanks of the aircraft wings are impacted by high-speed penetration bodies, the fuel tank wall plates can be damaged and deformed under the impact of water hammer impact, so that the structural strength of the wings and the aerodynamic performance of the aircraft are affected. When the penetration body speed reaches a certain threshold value, the rear wall plate of the oil tank can generate obvious petal-shaped tearing holes due to the impact of a water hammer. The shape and the size of the petal-shaped tearing hole are two important input parameters in the evaluation and the vulnerability analysis of the aircraft damage, and the two parameters can be generally obtained only through experiments or simulation, and the requirements of quick prediction of the aircraft fuel tank damage cannot be met due to the lack of a general theoretical quick calculation method.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention provides a calculation method for the petal-shaped tearing hole of the wall plate of the liquid filling box body triggered by the water hammer load, which has good prediction or calibration effects on experiments and simulation and has important significance on the damage evaluation of the aircraft oil tank.
The invention adopts the technical scheme that: a calculation method for petal-shaped tearing holes of a wall plate of a liquid filling box body triggered by water hammer load comprises the following steps:
s1, a high-speed penetration body (such as a projectile or a fragment) impacts liquid and moves in the liquid, and the pressure history of a towing impact wave generated by the high-speed penetration body is calculated;
taking the high-speed penetration body as a moving field source, calculating the pressure history P (t) of any observation point of the wall plate of the liquid filling box according to Bernoulli's law;
wherein: t is penetration time, and the initial moment is the moment when the high-speed penetration body impacts the fluid; τ is the cavity expansion time, and the initial time is the time when the high-speed penetration body reaches any field source position xi; v (V) p Real-time speed for high-speed penetration of the body; z is Z b (t) is the penetration depth of the high-speed penetration body at the time t; r is R b For the distance from the position of the high-speed penetration body at the time t to the observation point,z and w are the coordinates of any observation point in the fluid respectively; r is (r) o For the distance from the fluid point of high-speed penetration body impact to the observation point, +.>Xi is any field source on the penetration path, r is the distance from the position xi of any field source to the observation point, and +.>z ξ Is the coordinates of an arbitrary field source position xi; c is the speed of sound in the fluid; p (P) 0 Is the initial pressure of the fluid; ρ 0 Is the fluid density; />Is a potential function of the moving field source; t is t ξ The arrival time from the motion of the body to the xi is penetrated at high speed; τ is the delay time and its expression is τ=t-r/c; z is Z b (τ) is the penetration depth of the high-speed penetration body at τ; a (z) ξ ) B is an intermediate parameter, and the expression is as follows:
wherein: ΔP is the pressure difference between the inside and outside of a cavity formed by the high-speed penetration body impinging fluid, and the standard atmospheric pressure is usually 0.101MPa; a (z) ξ ) Is z ξ ＝Z b A (z) at (t) ξ ) A value; n is a constant, usually 2.3-3.4; e (E) p Is the kinetic energy of the fluid; [ dE p /dZ b (t)] ξ For the fluid kinetic energy at any field source ζ:
[dE p /dZ b (t)]| ξ ＝4πρ 0 Nζ 2 +πa 2 ΔP (7)
wherein: zeta is the intensity of the point source and,a is the cavity radius at any field source xi +.>For a first derivative of a with respect to time, i.e.>
V p The following control differential equation is satisfied:
wherein: m is the mass of high-speed penetration material, C L A coefficient of resistance to movement of the body in the fluid for high-speed penetration; consider the initial velocity V of the high-speed penetration body at time t=0 p ＝V 0 The initial condition can solve the real-time speed V of the high-speed penetration body at any moment p ；
S2, calculating the actual bearing pressure process P of the wall plate of the box body r (t), the total impulse I actually born;
the transmission phenomenon will occur when the towing shock wave and the wall plate of the box body act, so that the flow-solid coupling effect needs to be considered, and the pressure process P actually born by the wall plate of the box body is calculated r (t) and the total impulse I actually sustained.
According to Newton's second law, the motion control equation of the wall plate of the box body can be obtained:
wherein: m is the mass per unit area of the wall plate of the box body; u is the movement speed of the wall plate of the box body in unit area; the actual pressure history P of the wall plate r (t) is the superposition of reflected and transmitted waves:
P r (t)＝C R P(t)-ρ 2 Du (10)
wherein P (t) is the pressure history of the incident towing impact wave near the wall plate of the box body calculated by S1, ρ 2 For the density of the wall sheet material of the tank body, D is the shock wave velocity of the wall sheet of the tank body, d=c 0 +λu；c 0 And lambda is Hugoniot parameter, C of the wall plate material of the box body R Is the reflection coefficient; taking into account the initial condition of the tank wall plate velocity u=0 at time t=0, the actual pressure history P experienced by the tank wall plate can be solved r (t) and the actual impulse per unit area i:
i＝∫P r (t)dt＝mu 1 (11)
wherein: u (u) 1 Is the final movement speed of the wall plate of the box body in unit area.
The total impulse I born by the whole box wall plate is the area integral of the impulse of unit area actually born:
wherein: s is the area of a wall plate of the box body;
s3, calculating initial kinetic energy E obtained by the wall plate of the box body k ；
Initial kinetic energy E obtained by wall plate of box body k Is also the total energy actually taken in by the wall plate of the box body and is acted by the drag shock wave to do work W 1 Direct penetration work W of penetration body 2 Two parts are as follows:
E k ＝W 1 +W 2 (13)
drag shock wave work W 1 Can be obtained by impulse integration:
wherein: h is the thickness of the wall plate of the box body, a polar coordinate system is established by taking an exit point on the surface of the wall plate of the box body as an origin, the horizontal rightward direction is taken as a polar axis, and the anticlockwise direction is taken as a positive direction, and then r is w Is of any polar diameter, theta w L is the maximum polar diameter and is any polar angle;
direct penetration body penetration work W 1 The method can be calculated from the ballistic limit speed:
wherein: v bl Ballistic limit speed for penetration of a body panel;
s4, calculating dissipation energy E of the wall plate of the box body;
considering that the wall plate of the box body presents petal-shaped tearing holes, the total energy dissipation rate of the wall plate of the box bodyRate of energy dissipation by petal bending->And tear energy dissipation Rate->The composition is as follows:
petal bending energy dissipation ratioThe expression is:
wherein: m is M o Bending moment at the root of the petal; l (L) c Projection displacement is carried out on petals; l is the projection movement rate of petals; r is (r) ρ Is the radius of curvature of the root of the petal; θ is the included angle of the tips of each petal, and is generally 45 degrees; η is a bending moment gain factor, and the expression is as follows:
wherein: epsilon f Tensile fracture strain for the box wall material; d is the penetration body diameter;
tear energy dissipation ratioThe expression is:
wherein: delta t Opening and displacing the frontal crack tip of the wall plate material of the box body;
substituting equation (17) and equation (19) into equation (16) yields the total energy dissipation ratio E expression:
to satisfy the system energy minimization principle, r in formula (20) ρ As an independent variable, it is considered that,regarding as a dependent variable, let formula (20):
calculated from formula (21):
r ρ ＝r ρmin ＝1.3η 0.6 l c 0.6 H 0.2 δ t 0.2 (sinθ) 1.4 (22)
wherein: r is (r) ρmin In (20)R corresponding to the minimum value ρ A value;
substituting formula (22) into formula (20) and finishing to obtain:
the dissipated energy E of the tank wall panel can be obtained by time integration of equation (23):
wherein: t is t c Is the final time of penetration;
s5, calculating the size of the broken hole;
according to the law of conservation of energy, the dissipated energy E of the wall plate of the box body is equal to the initial kinetic energy E obtained by the wall plate of the box body k And (3) obtaining the composite (24):
substituting known parameters c, P 0 、ρ 0 、M、C L 、L、m、v bl 、ρ 2 、c 0 、λ、ε f 、C R 、S、d、θ、H、δ t 、M o Then, the petal displacement l can be obtained by solving the formula (25) c ：
Size of broken hole r c Can be obtained by petal displacement:
s6, calculating a petal shape curve and a damage area;
the petal shape curve equation can be deduced through the formula of total energy dissipation rate, and the coordinate x of the petal tip in the direction parallel to the wall plate of the box body and the coordinate y in the direction perpendicular to the wall plate of the box body respectively meet the following differential control equation:
wherein: s is the actual length of petals; r, q is a calculation parameter;
when x=0 and y=0 are considered, s=l c The boundary condition is solved for the interval s=0 to l c The petal curve can be solved by a numerical calculation method.
Area of injury D c Can be obtained from petal profile curves:
D c ＝d c 2 (30)
wherein: d, d c The shortest distance between two symmetrical petal curves, namely the side length of the damaged area is shown in figure 3.
The beneficial effects of the invention are as follows:
the invention combines the fundamental principles of fluid dynamics, fluid-solid coupling and solid dynamics, converts the solving problem of the petal-shaped broken hole size and shape into the solving problem of a differential equation, can efficiently calculate quantitative results according to the differential equation, and is used for guiding the design of the anti-destruction capability of an aircraft fuel tank for resisting the attack of a high-speed penetration body.
Drawings
FIG. 1 is a schematic illustration of a high-speed penetration body moving to a position within a fluid-filled tank;
the symbols in the drawings illustrate: the z axis is the penetration direction of the high-speed penetration body, the w axis is the arbitrary direction of the surface where the high-speed penetration body impacts the fluid point, the xi is the arbitrary field source, and the dz ξ To differentiate, dw in the z-direction, any field source ζ ξ For differentiating arbitrary field source xi in w direction, Z b (t) is the real-time penetration depth of a high-speed penetration body, a is the cavity radius at any field source xi, r 0 For impacting the distance from the fluid point to the observation point for the high-speed penetration body, R b The distance from the real-time position of the high-speed penetration body to the observation point is r, the distance from the random field source position xi to the observation point is r, and z and w are coordinates of the random observation point in the fluid;
FIG. 2 is a graph showing the change in wall panel opening size with total impact force applied to the wall panel after filling the tank;
FIG. 3 is a graph of petal profile obtained by a theoretical model, including a definition of the side length of the lesion area;
FIG. 4 is a graph showing the change of the damage area of the rear wall plate of the liquid filling box body under different speed working conditions.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
As shown in fig. 1, a schematic diagram of the high-speed penetration body moving to a certain position in the liquid filling box body is shown, after the high-speed penetration body penetrates through the front wall plate of the liquid filling box body, the high-speed penetration body moves in the direction of ballistic lines in the fluid, cavitation bubbles are formed behind the penetration body during the movement, and a small high-pressure area is formed in the area just in front of the head end of the penetration body, and the area is called a trailing shock wave. The damage of the back wall plate of the liquid filling box body is caused by various factors, and the strict solution is more complicated, so that in order to simplify the analysis, two parts which mainly cause damage, namely the towing shock wave and the penetration body, are used as the calculation basis of the damage of the back wall plate of the liquid filling box body.
The invention relates to a calculation method for petal-shaped tearing holes of a wall plate of a liquid filling box body triggered by water hammer load, which comprises the following steps:
s1, calculating the pressure history of a drag shock wave generated by the high-speed penetration body in the fluid.
Taking the high-speed penetration body as a moving point source, and calculating the pressure history P (t) of any observation point of the wall plate of the liquid filling box according to Bernoulli's law;
s2, the phenomenon of emission and transmission occurs when the towing shock wave and the wall plate of the box body act, so that the fluid-solid coupling effect needs to be considered, and the actual pressure history and the actual total impulse I born by the wall plate of the box body are calculated. Actual pressure history P of wall panel r (t) is a superposition of reflected and transmitted waves, and its expression is as follows:
P r (t)＝C R P(t)-ρ 2 Du
the total impulse I born by the whole box wall plate is the area integral of the impulse of unit area actually born:
s3, calculating the initial kinetic energy obtained by the wall plate of the box body. Initial kinetic energy E obtained by wall plate of box body k Is also the total energy actually taken in by the wall plate of the box body and is acted by the drag shock wave to do work W 1 Direct penetration work W of penetration body 2 Two parts are as follows:
E k ＝W 1 +W 2
s4, calculating the dissipation energy of the wall plate of the box body. Considering that the wall plate of the box body presents petal-shaped tearing holes, the total energy dissipation rate of the wall plate of the box bodyRate of energy dissipation by petal bending->And tear energy dissipation Rate->The composition is as follows:
for total energy dissipation rateAnd (3) performing time integration to obtain the dissipation energy E of the wall plate of the box body:
s5, calculatingAnd the size of the broken hole. According to the law of conservation of energy, the dissipated energy E of the wall plate of the box body is equal to the initial kinetic energy E obtained by the wall plate of the box body k . After substituting various parameters, the petal displacement l can be obtained c ：
Size of broken hole r c Can be obtained by petal displacement:
and S6, calculating a petal shape curve and a damage area. The petal shape curve equation can be deduced through a total energy dissipation rate formula, and the coordinate x of the petal tips in the directions parallel to the wall plates of the box body and the coordinate y of the petal tips in the directions perpendicular to the wall plates of the box body respectively meet the following differential control equation:
when x=0 and y=0 are considered, s=l c The boundary condition is solved for the interval s=0 to l c The petal curve can be solved by a numerical calculation method.
Area of injury D c Can be obtained from petal profile curves:
D c ＝d c 2
wherein: d, d c The shortest distance between two symmetrical petal curves, namely the side length of the damaged area is shown in figure 3.
Example 1
According to the calculation equation of the crack length and petal shape curve and the value of the model related parameters, model theoretical data of 4 working conditions corresponding to a direct trajectory experiment are calculated.
The parameters in this example are:
substituting each parameter into a calculation equation of the damage area and the petal shape curve to solve, obtaining theoretical data of a model, and obtaining a change curve of the wall plate hole breaking size of the liquid filling box body along with the total impulse born by the wall plate, the petal shape curve and a change chart of the damage area of the wall plate of the liquid filling box body under different speed working conditions through drawing software origin post-treatment.
As shown in FIG. 2, the change curve of the size of the broken hole of the rear wall plate of the liquid filling box body along with the total impulse born by the wall plate calculated by theory can obtain that the size of the broken hole of the wall plate of the box body and the total impulse born by the wall plate show obvious positive correlation.
As shown in fig. 3, the petal shape curve calculated by theory is that the coordinate x is located in the direction of the wall plate of the box body, the coordinate y is located in the direction vertical to the wall plate of the box body, the petal shape curve under four speeds is included in the figure, and the larger the penetration body speed is, the more the corresponding petal shape curve is opened.
As shown in the change chart of the damage area of the rear wall plate of the liquid filling box body under the working conditions of different speeds shown in fig. 4, the chart contains comparison between experimental and theoretical results, and the error between the experimental and theoretical results is obviously smaller.
Claims (6)
1. The calculation method for the petal-shaped tearing hole of the wall plate of the liquid filling box body triggered by the water hammer load is characterized by comprising the following steps of:
s1, impacting fluid by a high-speed penetration body and moving in the fluid, and calculating the pressure history of a drag shock wave generated by the high-speed penetration body;
taking the high-speed penetration body as a moving field source, calculating the pressure history P (t) of any observation point of the wall plate of the liquid filling box according to Bernoulli's law;
wherein: t is penetration time, and the initial moment is the moment when the high-speed penetration body impacts the fluid; τ is the cavity expansion time, and the initial time is the time when the high-speed penetration body reaches any field source position xi; v (V) p Real-time speed for high-speed penetration of the body; z is Z b (t) is the penetration depth of the high-speed penetration body at the time t; r is R b For the distance from the position of the high-speed penetration body at the time t to the observation point,z and w are the coordinates of any observation point in the fluid respectively; r is (r) o For the distance from the fluid point of high-speed penetration body impact to the observation point, +.>Xi is any field source on the penetration path, r is the distance from the position xi of any field source to the observation point, and +.>z ξ Is the coordinates of an arbitrary field source position xi; c is the speed of sound in the fluid; p (P) 0 Is the initial pressure of the fluid; ρ 0 Is the fluid density; />Is a potential function of the moving field source; t is t ξ The arrival time from the motion of the body to the xi is penetrated at high speed; τ is the delay time and its expression is τ=t-r/c; z is Z b (τ) is the penetration depth of the high-speed penetration body at τ; a (z) ξ ) B is an intermediate parameter, and the expression is as follows:
wherein: Δp is the pressure differential between the inside and outside of the cavity formed by the high-velocity penetration body impinging fluid; a (z) ξ ) Is z ξ ＝Z b A (z) at (t) ξ ) A value; n is a constant; e (E) p Is the kinetic energy of the fluid; [ dE p /dZ b (t)]| ξ For the fluid kinetic energy at any field source ζ:
[dE p /dZ b (t)]| ξ ＝4πρ 0 Nζ 2 +πa 2 ΔP (7)
wherein: zeta is the intensity of the point source and,a is the cavity radius at any field source xi +.>For a first derivative of a with respect to time, i.e.>
V p The following control differential equation is satisfied:
wherein: m is the mass of high-speed penetration material, C L A coefficient of resistance to movement of the body in the fluid for high-speed penetration; consider the initial velocity V of the high-speed penetration body at time t=0 p ＝V 0 The initial condition can solve the real-time speed V of the high-speed penetration body at any moment p ；
S2, calculating the actual bearing pressure process P of the wall plate of the box body r (t), the total impulse I actually born;
the transmission phenomenon will occur when the towing shock wave and the wall plate of the box body act, so that the flow-solid coupling effect needs to be considered, and the pressure process P actually born by the wall plate of the box body is calculated r (t) and the total impulse I actually sustained;
according to Newton's second law, a motion control equation of the wall plate of the box body is obtained:
wherein: m is the mass per unit area of the wall plate of the box body; u is the movement speed of the wall plate of the box body in unit area; the actual pressure history P of the wall plate r (t) is the superposition of reflected and transmitted waves:
P r (t)＝C R P(t)-ρ 2 Du (10)
wherein P (t) is the pressure history of the incident towing impact wave near the wall plate of the box body calculated by S1, ρ 2 For the density of the wall sheet material of the tank body, D is the shock wave velocity of the wall sheet of the tank body, d=c 0 +λu；c 0 And lambda is Hugoniot parameter, C of the wall plate material of the box body R Is the reflection coefficient; taking into account the initial condition of the tank wall plate velocity u=0 at time t=0, the actual pressure history P experienced by the tank wall plate can be solved r (t) and the actual impulse per unit area i:
i＝∫P r (t)dt＝mu 1 (11)
wherein: u (u) 1 The final movement speed of the wall plate of the box body in unit area is set;
the total impulse I born by the whole box wall plate is the area integral of the impulse of unit area actually born:
wherein: s is the area of a wall plate of the box body;
s3, calculating initial kinetic energy E obtained by the wall plate of the box body k ；
Initial kinetic energy E obtained by wall plate of box body k Is also the total energy actually taken in by the wall plate of the box body and is acted by the drag shock wave to do work W 1 Direct penetration work W of penetration body 2 Two parts are as follows:
E k ＝W 1 +W 2 (13)
drag shock wave work W 1 Can be obtained by impulse integration:
wherein: h is the thickness of the wall plate of the box body, a polar coordinate system is established by taking an exit point on the surface of the wall plate of the box body as an origin, the horizontal rightward direction is taken as a polar axis, and the anticlockwise direction is taken as a positive direction, and then r is w Is of any polar diameter, theta w L is the maximum polar diameter and is any polar angle;
direct penetration body penetration work W 1 The method can be calculated from the ballistic limit speed:
wherein: v bl Ballistic limit speed for penetration of a body panel;
s4, calculating dissipation energy E of the wall plate of the box body;
considering that the wall plate of the box body presents petal-shaped tearing holes, the total energy dissipation rate of the wall plate of the box bodyRate of energy dissipation by petal bending->And tear energy dissipation Rate->The composition is as follows:
petal bending energy dissipation ratioThe expression is:
wherein: m is M o Bending moment at the root of the petal; l (L) c Projection displacement is carried out on petals;projecting a movement rate for petals; r is (r) ρ Is the radius of curvature of the root of the petal; θ is the tip angle of each petal; η is a bending moment gain factor, and the expression is as follows:
wherein: epsilon f Tensile fracture strain for the box wall material; d is the penetration body diameter;
tear energy dissipation ratioThe expression is:
wherein: delta t Opening and displacing the frontal crack tip of the wall plate material of the box body;
substituting the formula (17) and the formula (19) into the formula (16) can obtain the total energy dissipation rateThe expression:
to satisfy the system energy minimization principle, r in formula (20) ρ As an independent variable, it is considered that,regarding as a dependent variable, let formula (20):
calculated from formula (21):
r ρ ＝r ρmin ＝1.3η 0.6 l c 0.6 H 0.2 δ t 0.2 (sinθ) 1.4 (22)
wherein: r is (r) ρmin In (20)R corresponding to the minimum value ρ A value;
substituting formula (22) into formula (20) and finishing to obtain:
the dissipated energy E of the tank wall panel can be obtained by time integration of equation (23):
wherein: t is t c Is the final time of penetration;
s5, calculating the size of the broken hole;
according to the law of conservation of energy, the dissipated energy E of the wall plate of the box body is equal to the initial kinetic energy E obtained by the wall plate of the box body k And (3) obtaining the composite (24):
substituting known parameters c, P 0 、ρ 0 、M、C L 、L、m、v bl 、ρ 2 、c 0 、λ、ε f 、C R 、S、d、θ、H、δ t 、M o Then, the petal displacement l can be obtained by solving the formula (25) c ：
Size of broken hole r c Can be obtained by petal displacement:
s6, calculating a petal shape curve and a damage area;
the petal shape curve equation can be deduced through the formula of total energy dissipation rate, and the coordinate x of the petal tip in the direction parallel to the wall plate of the box body and the coordinate y in the direction perpendicular to the wall plate of the box body respectively meet the following differential control equation:
wherein: s is the actual length of petals; r, q is a calculation parameter;
when x=0 and y=0 are considered, s=l c The boundary condition is solved for the interval s=0 to l c The petal curve can be solved by a numerical calculation method;
area of injury D c Can be obtained from petal profile curves:
D c ＝d c 2 (30)
wherein: d, d c The shortest distance of two symmetrical petal curves is the side length of the damaged area.
2. A method for calculating a petal-shaped tearing hole of a wall plate of a liquid filling box body initiated by a water hammer load according to claim 1, which is characterized in that: the pressure difference delta P between the inside and the outside of a cavity formed by the high-speed penetration body impinging fluid is 0.101MPa of standard atmospheric pressure.
3. A method for calculating a petal-shaped tearing hole of a wall plate of a liquid filling box body initiated by a water hammer load according to claim 1, which is characterized in that: the constant N is 2.3-3.4.
4. A method for calculating a petal-shaped tearing hole of a wall plate of a liquid filling box body initiated by a water hammer load according to claim 3, which is characterized in that: the constant N is taken to be 2.7.
5. A method for calculating a petal-shaped tearing hole of a wall plate of a liquid filling box body initiated by a water hammer load according to claim 1, which is characterized in that: the included angle theta between the tips of each petal is 45 degrees.
6. A method for calculating a petal-shaped tearing hole of a wall plate of a liquid filling box body initiated by a water hammer load according to claim 1, which is characterized in that: the calculation parameters r=0.95, q=0.4.
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