Rigid-body-like medical equipment earthquake vulnerability assessment method considering multi-motion-state coupling

Abstract

The invention discloses a rigid-body-like medical equipment earthquake vulnerability evaluation method considering multi-motion-state coupling, and aims to solve the problem that the earthquake vulnerability of wheeled medical equipment under the influence of factors such as strong shock, rolling, sliding-swinging coupling and non-uniform friction is difficult to accurately evaluate only depending on classic rigid body sliding or overturning criteria. Medical equipment is regarded as a rigid body, the motion state of the rigid body at each moment in the earthquake process is determined according to geometric parameters and supporting information of the rigid body, the gravitational acceleration and the earthquake oscillation time history, and the motion states comprise fixed foot support sliding, trundle rolling, swinging and sliding-swinging coupling. The maximum translation displacement and the maximum rotation angle of the rigid body are obtained based on the motion state, the damage state of the rigid body is judged according to the maximum translation displacement and the maximum rotation angle, nonlinear incremental dynamic analysis is conducted on the rigid body, an earthquake vulnerability function is obtained, the larger the median value of the earthquake vulnerability function is, the lower the earthquake vulnerability of the rigid body is, and otherwise, the higher the earthquake vulnerability of the rigid body is. The invention belongs to the field of shock resistance of medical instruments.

Description

Technical Field

[0001] This invention relates to the field of seismic resistance of medical devices, and specifically to a rapid assessment method for the seismic vulnerability of quasi-rigid body medical devices that considers the coupling of multiple motion states. Background Technology

[0002] The availability of medical equipment directly impacts the physical functioning of a hospital. After an earthquake, damage to medical equipment can easily threaten patient lives and cause severe economic losses. However, medical equipment is diverse, varying in shape, size, and usage conditions. Limited by time and cost, experiments and numerical simulations typically only cover the seismic performance of a limited number of medical equipment types, making it difficult to support hospital-wide equipment risk assessments and functional recovery decisions.

[0003] Current shaking table tests on wheeled medical equipment show that traditional rigid body motion equations and motion judgment criteria are not applicable to wheeled medical equipment. This finding reveals that relying solely on classical rigid body slip or overturning criteria to calculate the seismic vulnerability of wheeled medical equipment cannot accurately describe the true motion characteristics of the caster mechanism under strong earthquakes, especially under the influence of factors such as rolling, sliding-rocking coupling, and uneven friction. Therefore, there is an urgent need for a rapid method for calculating the seismic vulnerability of various types of medical equipment, including wheeled medical equipment, that is applicable under a wide range of parameter variations, can simultaneously consider multiple motion states, and covers all types of medical equipment. Summary of the Invention

[0004] To address the problem that relying solely on classical rigid body slip or overturning criteria makes it difficult to accurately assess the seismic vulnerability of wheeled medical devices under the influence of strong earthquakes and factors such as rolling, sliding-swaying coupling, and uneven friction, this invention proposes a method for assessing the seismic vulnerability of near-rigid-body medical devices that considers the coupling of multiple motion states.

[0005] The technical solution adopted in this invention is:

[0006] It includes the following steps:

[0007] S1. Treat the medical device as a two-dimensional homogeneous rigid body, or simply a rigid body, and collect the geometric parameters and support information of the rigid body;

[0008] S2. At the moment of an earthquake, based on the geometric parameters and support information of the rigid body, gravitational acceleration and seismic motion time history, determine the motion state of the rigid body at each moment during the earthquake. The motion states include fixed foot sliding, caster rolling, swaying and sliding-swaying coupling.

[0009] S3, according to the motion state of the rigid body at each moment in the earthquake process, the translation acceleration time history and the angular acceleration time history of the rigid body in the earthquake process are obtained, the translation acceleration time history and the angular acceleration time history are twice integrated to obtain the translation displacement time history and the rotation angle time history of the rigid body, and the maximum translation displacement and the maximum rotation angle of the rigid body are extracted according to the translation displacement time history and the rotation angle time history;

[0010] S4, judging the damage state of the rigid body based on the maximum translation displacement and the maximum rotation angle of the rigid body;

[0011] S5, based on S4, performing nonlinear incremental dynamic analysis on the rigid body to obtain a seismic vulnerability function, the greater the median value of the seismic vulnerability function, the lower the seismic vulnerability of the rigid body, and vice versa, the higher the seismic vulnerability of the rigid body.

[0012] The beneficial effects of the present application are:

[0013] The present application establishes a wheel type medical equipment seismic vulnerability evaluation method considering fixed foot support sliding, wheel rolling, rocking and sliding- rocking coupling, and containing uneven friction and collision recovery. A regular shape rigid body medical equipment is regarded as a two-dimensional homogeneous rigid body, which is simply referred to as a rigid body, and the geometric parameters and support information of the rigid body are collected. Under the input of the earthquake, the corresponding motion equation is determined according to the different motion states of the rigid body, and the displacement and overturning response of the wheel type medical equipment is obtained. On this basis, the maximum translation displacement and the maximum rotation angle of the rigid body in the earthquake process are obtained, so as to determine the damage state of the rigid body, and then the floor peak acceleration (PFA) is used for nonlinear incremental dynamic analysis on the damaged rigid body, and the displacement threshold and overturning The exceeding probability is counted, and the median value and the logarithmic standard deviation of the seismic vulnerability function are obtained by using the lognormal maximum likelihood fitting. The greater the median value, the lower the seismic vulnerability of the rigid body, and vice versa, the higher the seismic vulnerability of the rigid body. Based on the above, the evaluation accuracy of the seismic vulnerability of the wheel type medical equipment is improved.

[0014] The present application realizes the unified coverage of four types of motion of sliding, rolling, rocking and sliding- rocking coupling in the two-dimensional rigid body framework, supports state adaptive switching and collision recovery. Compared with full-scale test and high-fidelity simulation, the displacement and overturning response and vulnerability parameters can be obtained in batches. The present application compares and verifies this scheme through anesthetic machine and respirator shaking table test, accurately evaluates the large displacement and overturning risk of medical equipment, and provides a basis for hospital seismic design, equipment arrangement and function evaluation. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The flowchart of the method of the present application is shown in the figure;

[0016] Figure 2 The figure is an example of a small and medium-sized two-dimensional homogeneous rigid body medical equipment;

[0017] Figure 3 is a two-dimensional homogeneous rigid body geometry information and force diagram;

[0018] Figure 4 is a state diagram;

[0019] Figure 5 is a two-dimensional homogeneous rigid body displacement change diagram of unilateral unlocking casters;

[0020] Figure 6 is the relationship between the friction coefficient and the two-dimensional homogeneous rigid body translational displacement of the unilateral locking casters;

[0021] Figure 7 is the relationship between the friction coefficient and the two-dimensional homogeneous rigid body translational displacement of the ordinary foot support;

[0022] Figure 8 is the seismic vulnerability curve of a small independent floating medical device under ;

[0023] Figure 9 is the seismic vulnerability curve of a large independent floating medical device under ;

[0024] Figure 10 is the seismic vulnerability curve of a vertical trolley under ;

[0025] Figure 11 is the seismic vulnerability curve of a large independent floating medical device under ;

[0026] Figure 12 is the seismic vulnerability curve of a vertical trolley under ; DETAILED DESCRIPTION

[0027] Specific implementation one: combined with Figures 1-12 The present embodiment is a kind of rigid body medical equipment seismic vulnerability evaluation method considering multi-motion state coupling, it includes the following steps:

[0028] S1, the regular shape of rigid body medical equipment is regarded as two-dimensional homogeneous rigid body, simply called rigid body, the geometric parameters and support information of rigid body are collected.

[0029] The present application abstracts the regular shape of rigid body medical equipment as two-dimensional homogeneous rigid body, two-dimensional homogeneous rigid body refers to the rigid body with uniform mass distribution in two-dimensional plane. Rigid body refers to the object that shape and size do not change in motion and under the action of force, and the relative position of internal points does not change. For example Figure 2As shown, the regular-shaped rigid-body-like medical devices in the embodiment include electrocardiograph, electrocardiograph monitor, infusion pump, defibrillation monitor, hemorheology analyzer, blood gas analyzer, urine analyzer, flow cytometer, dialysis machine, respirator and anesthetic machine, etc.

[0030] As shown, in general, the support mode of the regular-shaped rigid-body-like medical devices (two-dimensional homogeneous rigid body) includes fixed foot props or casters, but in the embodiment, since the two-dimensional homogeneous rigid body belongs to two-dimensional plane, the number of fixed foot props and casters is considered as two, and the two fixed foot props or two casters are oppositely arranged on the bottom surface of the rigid body to maintain the balance of the regular-shaped rigid-body-like medical devices and facilitate use. Figure 3

[0031] When the support mode is fixed foot props, the support information includes the height of the fixed foot props , the distance between the two fixed foot props , the static friction coefficient and the dynamic friction coefficient of each fixed foot prop with the ground: the static friction coefficient of the left fixed foot prop with the ground , the dynamic friction coefficient of the left fixed foot prop with the ground , the static friction coefficient of the right fixed foot prop with the ground , and the dynamic friction coefficient of the right fixed foot prop with the ground .

[0032] When the support mode is casters, the support information includes the wheelbase of the two casters , whether the casters are in locked state or unlocked state, the equivalent rolling resistance parameter of each caster, the static friction coefficient and the dynamic friction coefficient of each caster with the ground: the static friction coefficient of the left caster with the ground in locked state , the dynamic friction coefficient of the left caster with the ground in locked state , the static friction coefficient of the right caster with the ground in unlocked state , and the dynamic friction coefficient of the right caster with the ground in unlocked state . The locked state and the unlocked state are not limited to which side, as long as one side of the caster is in locked state and the other side is in unlocked state.

[0033] The geometric parameters include the body height , the body width , the mass , the center of mass and the polar moment of inertia . The body of the rigid body is the core part of the rigid body excluding the support (fixed foot prop or caster).

[0034] ​S2, at the moment of earthquake occurrence, the initial motion state of the rigid body in the earthquake is determined according to the geometric parameters and support information of the rigid body, the gravity acceleration and the time history of ground motion, the initial motion state is fixed foot support sliding or wheel rolling or rocking or sliding- rocking coupling.

[0035] At the initial moment of earthquake occurrence, the default rigid body displacement and velocity are zero, the rigid body is in a static state, and the two side supports are in contact and under pressure. First, it is determined whether the rigid body uses a fixed foot support or a wheel support, and then according to the static friction between the rigid body and the ground at this time, the gravity acceleration and the time history of ground motion, it is determined which of the fixed foot support sliding, wheel rolling, rocking and sliding- rocking coupling the initial motion state of the rigid body changes from static to under the action of ground motion, so as to determine the initial motion state (first motion mode) of the rigid body in the process of earthquake occurrence, as shown in Figure 4

[0036] According to the initial motion state, the motion state of the rigid body at the next moment of the initial motion state in the earthquake is determined, and so on, to obtain the motion state of the rigid body at each moment in the process of earthquake, the motion state includes fixed foot support sliding, wheel rolling, rocking and sliding- rocking coupling. This step determines the motion state of the rigid body at each moment in the process of earthquake through the dynamic equation of fixed foot support sliding, wheel rolling, rocking and sliding- rocking coupling, and the rigid body performs adaptive switching between states in the process of earthquake according to the motion state at each moment.

[0037] S21, sliding state of fixed foot support:

[0038] When the average static friction between the fixed foot support of the rigid body and the ground is not enough to maintain the static state of the rigid body, the rigid body starts to slide, and the judgment condition for the sliding of the rigid body is:

[0039] (1)

[0040] wherein, is the average static friction coefficient between the fixed foot support of the rigid body and the ground, , is the gravity acceleration, is the vertical acceleration of ground motion, unit , is the absolute value of the horizontal acceleration of ground motion, unit , the vertical acceleration of ground motion and the horizontal acceleration of ground motion are obtained from the time history of ground motion in the horizontal direction and the vertical direction.

[0041] If the rigid body is always in a sliding state, the only resistance to the horizontal inertial force of the rigid body under the action of ground motion is the friction between the rigid body and the ground, and the horizontal force balance equation of the rigid body is:

[0042] (2)​

[0043] where, is the translational acceleration of the rigid body, unit , is the maximum friction force between the rigid body and the ground when the rigid body starts to slip.

[0044] Assuming that the rigid body obeys Coulomb-type friction model, the maximum friction force between the rigid body and the ground when the rigid body starts to slip is:

[0045] (3)

[0046] where, is the translational velocity of the rigid body, unit , is the average dynamic friction coefficient between the fixed foot support of the rigid body and the ground, , is a sign function, defined as:

[0047] (4)

[0048] The translational acceleration of the rigid body slipping is obtained by combining equation (2) and equation (3):

[0049] (5)

[0050] The slip stops when the relative velocity between the ground and the rigid body reaches zero, which is the termination condition of the rigid body slipping.

[0051] S22, rolling state of the caster:

[0052] There is no research on the motion law of wheeled medical devices and the corresponding simplified motion model, so the present application proposes an equivalent rolling resistance model using a two-section Coulomb friction model to simulate the rolling state of the caster of the wheeled medical device. When the support mode of the rigid body is the caster, the rigid body is pushed by sufficient external force to occur the caster rolling behavior in the unlocked state of the caster. At this time, the caster is in contact with the ground, and the friction between the two drives the caster to rotate around the wheel shaft to make the rigid body move on the ground. During the movement, the rotation of the wheel shaft produces a certain resistance to cause energy dissipation. In the case of free movement, the caster rolling will stop in a period of time, so the present application simplifies the resistance generated by the wheel shaft to a resistance coefficient related to the vertical pressure of the wheeled medical device , the resistance coefficient is similar to the friction coefficient, and the present embodiment sets .

[0053] The invention is divided into two states: all wheels unlocked state and single wheel unlocked state. In the all wheels unlocked state, the equivalent rolling resistance model is used to simulate the rolling effect when all wheels are unlocked, and the sliding mode is switched when the switching criterion is met. The specific process is as follows:

[0054] The starting condition of the rolling state when all wheels are unlocked can be compared with the starting condition of the sliding state, that is, when the equivalent static friction between the unlocked wheels and the ground is not enough to maintain the static state of the rigid body, the rigid body starts to roll. The determination condition of the rigid body rolling is:

[0055] (6)

[0056] Wherein, , is the equivalent static friction coefficient between the unlocked wheels and the ground. Since the static friction coefficients generated by the two wheels of the rigid body in the unlocked state can be considered the same value in calculation, only the static friction coefficient of the single wheel unlocked state is calculated in the equivalent static friction coefficient. The invention selects the static friction coefficient of the right wheel unlocked state .

[0057] When the horizontal inertia force of the rigid body under the action of earthquake is less than the maximum static friction between the wheels and the ground, the rigid body will roll purely. The determination condition of the pure rolling is:

[0058] (7)

[0059] In the pure rolling state, the rigid body wheels are in full contact with the ground without relative sliding, and the friction generated between them provides the power source for the wheel rotation, as shown below:

[0060] (8)

[0061] (9)

[0062] Wherein, is the sum of the equivalent dynamic friction and resistance of the unlocked wheels of the rigid body , and the equivalent dynamic friction coefficient and the equivalent static friction coefficient are selected in the same way.

[0063] The translation acceleration of the rigid body in the pure rolling state is obtained from equation (8) and equation (9):

[0064] (10)

[0065] When the horizontal inertial force of the rigid body exceeds the maximum static friction force between the caster and the ground, the caster will slide relative to the ground in the rolling state, and the friction between the caster surface and the ground reaches the maximum sliding friction force, and the rolling-sliding judgment condition is obtained as follows:

[0066] (11)

[0067] The translational acceleration of the rigid body in the rolling-sliding state is:

[0068] (12)

[0069] The caster will switch between the pure rolling state and the rolling-sliding state with the change of the horizontal acceleration of the earthquake motion during the rolling process, until the end of the earthquake motion time history loading, and the speed of the rigid body is reduced to zero, the rolling state ends, and the rigid body is static.

[0070] As Figures 5-7 shown, when the support mode of the rigid body is the caster, and one side of the caster is in the locked state and the other side of the caster is in the unlocked state (single side caster unlocked state), under the action of the earthquake motion, the friction between the unlocked caster of the rigid body and the ground provides power for the motion of the rigid body, and the friction between the caster in the locked state and the ground is resistance to prevent the relative sliding of the rigid body on the ground, so when the rigid body swings and the unlocked caster collides with the ground, the energy loss during the collision process is small, at this time the potential energy is converted into the kinetic energy of the caster rolling, and the rigid body can easily obtain greater motion speed. Based on the above, the present application proposes an equivalent assumption:

[0071] The motion behavior of the caster in the locked state of the rigid body is equivalent to the sliding behavior in the low friction state, and the friction coefficient in the low friction state is less than the average friction coefficient of all casters.

[0072] Based on the above assumption, when the horizontal inertial force of the rigid body is less than the maximum static friction force between the caster and the ground, the translational acceleration of the rigid body in the rolling-sliding behavior of the caster in the locked state is:

[0073] (13)

[0074] The size of the friction coefficient in this state is obtained by the product of the static friction coefficient in the locked state and the reduction coefficient . According to experience, .

[0075] When the horizontal inertial force of the rigid body exceeds the maximum static friction force between the caster and the ground, the translational acceleration of the rigid body in the rolling-sliding behavior under the condition of locking one side caster is formula (12). When the horizontal inertial force of the rigid body is equal to the maximum static friction force between the caster and the ground, the rigid body is in a static state or uniform linear motion.

[0076] S23, rocking state:

[0077] When the overturning moment of the fixed foot support or caster of the rigid body is greater than the resisting moment, the rigid body will rock, and the judgment condition of rocking is:

[0078] (14)

[0079] wherein, is the critical angle of overturning of the rigid body, unit rad.

[0080] The motion equation of the single degree of freedom system can be obtained by the torque balance equation or the Lagrange equation at the rotation angle, and has been applied in many documents. The motion equation of the rigid body in the rocking state is:

[0081] (15)

[0082] wherein, is the angular acceleration of the rigid body, unit , is the rotation angle of the rigid body, unit rad, is the distance between the center of gravity of the rigid body and the rotation support point, unit , the rotation support point is the fixed foot support or caster of one side, is the polar moment of inertia, unit .

[0083] Solving the angular acceleration of the rigid body in formula (15) , the angular acceleration of the rigid body in the pure rocking behavior caused by the horizontal acceleration of the ground motion is:

[0084] (16)

[0085] When the rigid body is in pure rocking motion, it rotates around one of the support points (single fixed foot support or caster) each time, and then switches the rotation support point at a certain time, at which time, the impact between the rigid body and the ground will occur, resulting in energy dissipation. Assuming that the impact is instantaneous, the energy loss due to the impact can be reflected by using the recovery coefficient, and the angular velocity of the rigid body is quantified:

[0086] (17)

[0087] wherein, is Angular velocity of the rigid body at time (after impact), unit is , is Angular velocity of the rigid body at time (before impact), unit is , is the restitution coefficient, which is calculated by the conservation of angular momentum before and after impact:

[0088] (18)

[0089] The determination of the rocking mode takes the compressed support angle as the rotation point, and the rocking response is solved according to the Lagrange equation, and the angular velocity is updated according to the restitution coefficient at the support point switching or collision, and the translational velocity is attenuated if necessary.

[0090] S24, sliding-rolling coupling state

[0091] The sliding-rolling behavior is characterized by the simultaneous occurrence of sliding and rolling behaviors, and the sliding-rolling behavior can start from three states of static, sliding or rolling. Assuming that the sliding-rolling coupling behavior starts, the rigid body will always maintain the sliding-rolling coupling behavior until the overturning or the end of the seismic motion, and then the rigid body tends to be static. If this assumption is true, the motion equation of the sliding-rolling coupling can be divided into two behaviors of pure sliding and pure rolling.

[0092] If the rigid body starts to slide during the rolling process (rolling-sliding), the horizontal inertia force acting on the rigid body must exceed the friction resistance at the rocking point, and then the determination condition calculation process is:

[0093] Assuming that the rigid body is in a rolling state, the accelerations in the horizontal and vertical directions are respectively:

[0094] Translational acceleration :

[0095] (19)

[0096] Vertical acceleration :

[0097] (20)

[0098] where, is the angular velocity of the rigid body ( ).

[0099] According to the static equilibrium equation, the horizontal and vertical action forces of the ground can be solved: and the vertical action force :

[0100] (21)

[0101] (22)

[0102] Substitute equation (19) into equation (21) and equation (20) into equation (22), and The final expression is:

[0103] (23)

[0104] (24)

[0105] When the horizontal reaction force exceeds the friction force at the pivot point, the rigid body will start to slide, and the start condition of sliding during rocking is:

[0106] (25)

[0107] where, is the static friction coefficient at the pivot point, and the pivot point is a unilateral fixed foot prop or caster, for example, when the pivot point is a left fixed foot prop, when the pivot point is a left caster, and so on.

[0108] Substitute equation (23) and equation (24) into equation (25), and the determination condition of rocking-sliding behavior is:

[0109] (26)

[0110] When the overturning moment generated by the horizontal acceleration of ground motion exceeds the restoring moment of the rigid body, the rigid body will start to rock in a sliding state, and the determination condition is:

[0111] (27)

[0112] The motion control equation of sliding-rocking can be derived by Lagrange equation, which characterizes the dynamic characteristics of the rigid body through its total kinetic energy and potential energy.

[0113] Finally, after satisfying equation (26) or equation (27), the translational acceleration of the rigid body in the sliding-rocking coupling behavior is:

[0114] (28)

[0115] where, is the friction force acting on the rigid body, which is expressed as:

[0116] (29)

[0117] The angular acceleration of a rigid body in sliding-rocking coupled behavior is:

[0118] (30)

[0119] In the sliding-rocking coupling behavior, after a collision, the angular velocity of the rigid body is updated (decreased) according to equation (17), and the translational velocity is updated (decreased) according to the following equation:

[0120] (31)

[0121] in, for The translational velocity of the rigid body at the moment (after the collision). for The angular velocity of the rigid body at the moment (before the collision).

[0122] S3. Based on the motion state of the rigid body at each moment during the earthquake, obtain the time history of the translational acceleration of the rigid body during the earthquake. and angular acceleration time history For translational acceleration time history and angular acceleration time history By performing a second integration, the translational displacement time history of the rigid body is obtained. and turning time history According to the translational displacement time history and turning time history Extracting the maximum translational displacement of a rigid body and maximum turning angle .

[0123] S4, Based on the maximum translational displacement of a rigid body and maximum turning angle The damage state of a rigid body is determined, and the damage state is divided into three levels, including:

[0124] (1) intact ( ):when , and At this time, the rigid body does not suffer any damage, and its state is characterized by being at rest, slightly sliding, or slightly swaying. The translational displacement threshold can be set according to the type of medical equipment and the usage scenario. For example, the translational displacement threshold for an upright trolley is 20 cm, and the translational displacement threshold for a small floating desktop device is 10 cm.

[0125] (2) Minor injury ):when , and When a rigid body suffers minor damage that can be easily repaired to restore its original function, it is characterized by large-scale sliding, accompanied by slight shaking or collision.

[0126] (3) Severe injury ( ):when When the rigid body suffers severe damage requiring replacement, the state manifests as severe shaking leading to the overturning of the rigid body.

[0127] S5. Based on S4, perform nonlinear incremental dynamic analysis (IDA) on the rigid body to obtain the seismic vulnerability function and its median value. The larger the value, the lower the seismic vulnerability of the rigid body; conversely, the smaller the value, the higher the seismic vulnerability of the rigid body. The specific process is as follows:

[0128] Select strip( Representative historical ground motion time histories were used, and each ground motion time histories was amplitude-modulated according to its peak ground acceleration (PFA). This invention sets the amplitude modulation range to 0.1g~2.5g with a step size of 0.1g, and statistically analyzes the peak ground acceleration (PFA) of each time histories. and Frequency of occurrence Calculate separately and The corresponding exceedance probability, exceedance probability = Assuming the failure probability of the rigid body at each peak ground acceleration (PFA) follows a log-normal distribution, the median value of the seismic vulnerability function is obtained by fitting the log-normal maximum likelihood. With log standard deviation Establish earthquake vulnerability function :

[0129] (32)

[0130] in, It is the standard normal distribution function. It is in a damaged state. In equation (32), For each damage state, the translational displacement threshold and overturning critical angle are given. For engineering requirements parameters, the maximum translational displacement corresponding to each damage state is given. and maximum turning angle In the calculation of equation (32), the translational displacement threshold corresponds to the maximum translational displacement, and the overturning critical angle corresponds to the maximum rotation angle.

[0131] This invention achieves unified coverage of four types of motion—sliding, rolling, rocking, and sliding-rocking coupled motion—within a two-dimensional homogeneous rigid frame, supporting adaptive switching and collision recovery across multiple motion states. Compared to full-scale testing and high-fidelity simulation, this invention can obtain displacement, overturning response, and vulnerability parameters in batches.

[0132] Embodiment

[0133] The rigid-like medical devices are classified into three categories according to the use state and support mode, i.e. small independent floating medical device, large independent floating medical device and vertical trolley. The floating refers to the non-anchored connection with the main building structure, which can be freely moved or carried. The small independent floating medical device has a length, width and height less than 50 cm, such as electrocardiograph, electrocardio monitor, etc., excluding medical devices with casters. The large independent floating medical device has a length, width and height greater than 50 cm, such as blood gas analyzer, blood rheology analyzer, etc., excluding medical devices with casters. The vertical trolley is a medical device placed on the ground with casters. The rigid-like medical devices include electrocardiograph, electrocardio monitor, infusion pump, defibrillation monitor, blood rheology analyzer, urine analyzer, flow cytometer, dialysis machine, respirator, anesthetic machine, etc.

[0134] Step one, collecting detailed information of each rigid-like medical device, including device name, purpose, brand, model, size, mass, placement mode, support mode (fixed foot support or caster) and support information (see S1). According to the size and mass of each medical device, the average size and mass of the medical device are obtained, which represents the size and mass of the medical device to ensure the authority and effectiveness of the data. For example, by checking the size information of 20 brands and models of anesthetic machines, the average value is taken as the size and mass of the anesthetic machine (this type of device) for seismic vulnerability assessment.

[0135] Step two, since the environment in which the rigid-like medical device is placed determines the different friction it receives, the specific friction coefficient value cannot be given in the public information that can be consulted. Here, the present application combines existing literature and various test results, and assumes that the static friction coefficient between small independent floating medical devices and large independent floating medical devices and the ground is 0.45, and the static friction coefficient between vertical trolleys and the ground is 0.40.

[0136] According to the above information, and the S2 in the first specific embodiment, the motion state of each rigid-like medical device at each time during the earthquake is calculated, and the determination condition of the motion state at each time, the translation acceleration and the angular acceleration of the rigid body are obtained.

[0137] Step three, according to the translation acceleration and the angular acceleration of each rigid-like medical device at each time during the earthquake, the translation acceleration time history and the angular acceleration time history of the rigid-like medical device during the earthquake are obtained. The translation displacement time history and the rotation angle time history of the rigid-like medical device are obtained by twice integrating the translation acceleration time history and the angular acceleration time history .According to the translational displacement time history and turning time history Extracting the maximum translational displacement of rigid body-like medical devices and maximum turning angle .

[0138] Step 4: Maximum translational displacement based on rigid body-like medical device and maximum turning angle The damage state of the rigid-body-like medical device is determined (see S4). Then, nonlinear incremental dynamic analysis is performed on the damaged rigid-body-like medical device (see S5). In this implementation, 20 representative ground motion time history records from the ATC63 dataset are selected as inputs for the seismic vulnerability analysis of the rigid-body-like medical device. All ground motion time history records are amplitude-modulated from 0.1g to 2.5g according to the peak ground acceleration (PFA), with intervals of 0.1g, to complete the amplitude modulation. Finally, the seismic vulnerability function of each rigid-body-like medical device is obtained, along with the median value of the seismic vulnerability function. The larger the value, the lower the seismic vulnerability of the rigid body; conversely, the smaller the value, the higher the seismic vulnerability of the rigid body.

[0139] Step 5: Based on the category of each rigid-body medical device and its seismic vulnerability function, obtain the vulnerability curves and parameter tables for each category of rigid-body medical device. The parameter table is shown in Table 1, which can be directly used for hospital functional assessment and design. The vulnerability curves are shown in... Figures 8-12 The parameter tables for each type of rigid body medical device are compiled to form a vulnerability parameter library for each category of medical device under DS1 and DS2.

[0140] Table 1

[0141]

[0142] To ensure mobility and portability, wheeled equipment often has a small aspect ratio, and locked wheeled equipment is prone to significant sliding displacement under earthquake conditions. When conducting a physical function evaluation of a hospital building, the corresponding vulnerability parameter can be selected based on the equipment name in the vulnerability parameter library. If the required medical equipment type is not found in the vulnerability parameter library, a similar vulnerability parameter can be selected based on the equipment type and aspect ratio.

[0143] This embodiment uses vibration table tests of anesthesia machines and ventilators to compare and verify the displacement response of the invention, in order to check the reduction factor. coefficient of recovery drag coefficient The rationality of the parameter selection is determined, and the vulnerability parameters of the corresponding category equipment in the vulnerability parameter library are corrected according to the rationality.

[0144] The above calculation examples of the present application are only used to illustrate the calculation model and the calculation process of the present application, and are not limited to the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art, and it is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application still fall within the protection scope of the present application.

Claims

1. A method for assessing the seismic vulnerability of quasi-rigid-body medical devices considering multi-motion state coupling, characterized in that: It includes the following steps: S1. Treat the medical device as a two-dimensional homogeneous rigid body, or simply a rigid body, and collect the geometric parameters and support information of the rigid body; S2. At the moment of an earthquake, based on the geometric parameters and support information of the rigid body, gravitational acceleration and seismic motion time history, determine the motion state of the rigid body at each moment during the earthquake. The motion states include fixed foot sliding, caster rolling, swaying and sliding-swaying coupling. S3. Based on the motion state of the rigid body at each moment during the earthquake, obtain the translational acceleration time history and angular acceleration time history of the rigid body during the earthquake. Perform a second integration on the translational acceleration time history and angular acceleration time history to obtain the translational displacement time history and rotational time history of the rigid body. Extract the maximum translational displacement and maximum rotational angle of the rigid body based on the translational displacement time history and rotational time history. S4. Determine the damage state of a rigid body based on its maximum translational displacement and maximum rotation angle. S5. Based on S4, perform nonlinear incremental dynamic analysis on the rigid body to obtain the seismic vulnerability function. The larger the median value of the seismic vulnerability function, the lower the seismic vulnerability of the rigid body, and vice versa.

2. The seismic vulnerability assessment method for quasi-rigid-body medical devices considering multi-motion state coupling as described in claim 1, characterized in that: The medical equipment in S1 includes an electrocardiograph, a cardiac monitor, an infusion pump, a defibrillator monitor, a hemorheology analyzer, a blood gas analyzer, a urine analyzer, a flow cytometer, a dialysis machine, a ventilator, and an anesthesia machine.

3. The seismic vulnerability assessment method for quasi-rigid-body medical devices considering multi-motion state coupling as described in claim 1, characterized in that: The geometric parameters of the rigid body in S1 include the height of the rigid body. Main body width ,quality Center of mass and polar moment of inertia .

4. The seismic vulnerability assessment method for quasi-rigid-body medical devices considering multi-motion state coupling as described in claim 1, characterized in that: The rigid body in S1 is supported by fixed legs or casters, with two fixed legs and two casters. The two fixed legs or two casters are arranged opposite to each other on the bottom surface of the rigid body. When the support method is fixed foot support, the support information includes the height of the fixed foot support. Spacing between the fixed feet on both sides And the static and dynamic friction coefficients between each fixed foot support and the ground; When the support method is casters, the support information includes the wheelbase of both casters. The parameters include whether the casters are locked or unlocked, the equivalent rolling resistance parameters of each caster, and the static and dynamic friction coefficients between each caster and the ground.

5. The seismic vulnerability assessment method for quasi-rigid-body medical devices considering multi-motion state coupling according to claim 4, characterized in that: When the motion state in S2 is fixed foot support sliding, the condition for determining that the rigid body slides is: （1） in, The average static friction coefficient between the rigid fixed foot support and the ground. , The static friction coefficient between the left fixed foot support and the ground is given. The static friction coefficient between the right fixed foot support and the ground is given. It is the acceleration due to gravity. This refers to the vertical acceleration due to seismic motion. This refers to the horizontal acceleration due to earthquakes. This represents the absolute value of the horizontal acceleration of the ground motion. The vertical and horizontal accelerations of the ground motion are obtained from the ground motion time history. When equation (1) is satisfied, the translational acceleration of the rigid body sliding is: （2） in, Let x be the translational acceleration of the rigid body. Let be the average coefficient of dynamic friction between the rigid fixed foot support and the ground. , The coefficient of dynamic friction between the left fixed foot support and the ground is given. The coefficient of dynamic friction between the right fixed foot support and the ground. Let be the translational velocity of the rigid body. .

6. The seismic vulnerability assessment method for quasi-rigid-body medical devices considering multi-motion state coupling according to claim 5, characterized in that: In S2, when the motion state is when the casters are rolling, it is divided into two states: both casters are fully unlocked and one caster is unlocked. 1) When both casters are fully unlocked, the condition for determining whether a rigid body rolls is as follows: （3） in, Let be the equivalent static friction coefficient between the caster and the ground in the rigid body unlocked state. , The static friction coefficient between the right caster and the ground when the caster is unlocked. The drag coefficient, ; When equation (3) is satisfied, the rolling of the caster includes pure rolling and rolling-sliding, then: The condition for determining whether a rigid body is rolling purely is: （4） in, The static friction coefficient between the left caster and the ground when locked. When equation (4) is satisfied, the translational acceleration of the rigid body during pure rolling is: （5） in, The coefficient of kinetic friction between the right caster and the ground when the caster is unlocked; The condition for determining whether a rigid body is rolling-sliding is: （6） When equation (6) is satisfied, the translational acceleration of the rigid body during rolling-sliding is: （7） in, The coefficient of dynamic friction between the left caster and the ground when locked. 2) The single-sided caster unlock state is when one side of the caster is locked and the other side of the caster is unlocked; With one caster unlocked, the rigid body undergoes rolling-sliding. Assuming the rigid body's motion is equivalent to sliding under low-friction conditions, and the coefficient of friction under low-friction conditions is less than the average coefficient of friction of all casters, then: When the horizontal inertial force of the rigid body is less than the maximum static friction between the caster and the ground, the translational acceleration of the rigid body during rolling and sliding is: （8） in, This is the reduction factor. ; When the horizontal inertial force of the rigid body exceeds the maximum static friction between the caster and the ground, the translational acceleration of the rigid body during rolling and sliding is given by equation (7). When the horizontal inertial force of a rigid body is equal to the maximum static friction between the caster and the ground, the rigid body is either at rest or in uniform linear motion.

7. The seismic vulnerability assessment method for quasi-rigid-body medical devices considering multi-motion state coupling according to claim 6, characterized in that: When the motion state in S2 is swaying, the condition for determining whether the rigid body is swaying is: （9） in, The overturning critical angle of a rigid body; When equation (9) is satisfied, the equation of motion of the rigid body in the swaying state is: （10） in, Let be the angular acceleration of the rigid body. Let be the rotation angle of the rigid body. This is the distance between the center of gravity of the rigid body and the rotational support point, which is a fixed foot support or caster on one side. Solve for the angular acceleration of the rigid body in equation (10). The angular acceleration of the rigid body's pure swaying behavior caused by the horizontal acceleration of the seismic motion is obtained: （11） However, when the rigid body changes its rotational support point, a collision occurs between the rigid body and the ground. Assuming the collision is instantaneous, the angular velocity of the rigid body after the collision is: （12） in, for The angular velocity of the rigid body at any given moment, for The angular velocity of the rigid body at any given moment, The coefficient of restitution is calculated using the conservation of angular momentum before and after the collision: （13）。 8. The seismic vulnerability assessment method for quasi-rigid-body medical devices considering multi-motion state coupling according to claim 7, characterized in that: When the motion state in S2 is a sliding-swing coupling, the condition for determining whether the rigid body undergoes sliding-swing is: （14） The condition for determining whether a rigid body is swaying or sliding is: （15） When equation (14) or equation (15) is satisfied, the translational acceleration of the rigid body undergoing sliding-rocking coupling is: （16） in, Friction acting on a rigid body is expressed as: （17） The angular acceleration of a rigid body undergoing sliding-rocking coupling is: （18） In the sliding-rocking coupling behavior, after a collision of rigid bodies, the angular velocity is updated according to equation (12), and the translational velocity is updated according to the following equation: （19） in, for The translational velocity of the rigid body at any given moment. for The angular velocity of the rigid body at any given moment.

9. The seismic vulnerability assessment method for quasi-rigid-body medical devices considering multi-motion state coupling according to claim 8, characterized in that: In step S3, based on the motion state of the rigid body at each moment during the earthquake, the translational acceleration time history and angular acceleration time history of the rigid body during the earthquake are obtained. A second integration is performed on the translational acceleration time history and angular acceleration time history to obtain the translational displacement time history and rotational time history of the rigid body. The maximum translational displacement and maximum rotational angle of the rigid body are extracted based on the translational displacement time history and rotational time history. The specific process is as follows: Based on the translational acceleration of the rigid body's motion at each moment during the earthquake. and angular acceleration The translational acceleration time history of the rigid body during the earthquake was obtained. and angular acceleration time history The translational acceleration time history was analyzed separately. and angular acceleration time history By performing a second integration, the translational displacement time history of the rigid body is obtained. and turning time history According to the translational displacement time history and turning time history Extracting the maximum translational displacement of a rigid body and maximum turning angle .

10. The seismic vulnerability assessment method for quasi-rigid-body medical devices considering multi-motion state coupling according to claim 9, characterized in that: The damage state of the rigid body in S4 is determined based on its maximum translational displacement and maximum rotation angle. The specific process is as follows: Damage status includes intact status Minor injury and severe injury ; (1) When , and At that time, the rigid body is in a perfect state. , The translational displacement threshold; (2) When , and At that time, the rigid body suffered minor damage. ; (3) When At that time, the rigid body was severely damaged. .

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