Method for predicting dummy head injury during automobile collision
A method for predicting dummy head injury during an automobile collision includes: enabling a dummy head to collide with a rigid flat plate; obtaining a first data set in a collision process; calculating the maximum contact force of the dummy head and the rigid flat plate in the collision process according to the first data set; dividing a duration of the collision process into a plurality of time intervals; and calculating an injury value of the dummy head in each time interval according to the maximum contact force, and selecting the maximum injury value as a target injury value. The method provided by the present application may realize prediction for the head injury under different scene working conditions, and has the advantages of being simple in test flow, and high in prediction precision.
1. A method for predicting dummy head injury during an automobile collision, comprising following steps:
enabling a dummy head to collide with a rigid flat plate, wherein the dummy head is a hollow spherical shell body;
obtaining a first data set in a collision process, wherein the first data set at least comprises: a mass, radius, a shell body thickness and a pre-collision speed of the dummy head, as well as a mass and a pre-collision speed of the rigid flat plate; and the pre-collision speeds are speeds when the dummy head just makes contact with the rigid flat plate;
calculating a maximum contact force of the dummy head and the rigid flat plate in the collision process according to the first data set;
dividing a duration of the collision process into a plurality of time intervals; and
calculating an injury value of the dummy head in each time interval according to the maximum contact force, and selecting the maximum injury value as a target injury value, wherein the target injury value is used for representing an injury degree of the dummy head in the collision process;
wherein the calculating the maximum contact force of the dummy head and the rigid flat plate in the collision process according to the first data set comprises the following steps:
calculating a post-collision speed of the dummy head and a post-collision speed of the rigid flat plate according to the kinetic energy theorem and the first data set; the post-collision speeds are speeds at the end moment of the collision between the dummy head and the rigid flat plate; and
calculating the maximum contact force F max of the dummy head and the rigid flat plate in the collision process in combination with the law of energy conservation and according to the first data set, the post-collision speed of the dummy head and the post-collision speed of the rigid flat plate;
wherein the post-collision speed of the dummy head is calculated according to following formula:
v
1
′
=
v
1
+
∫
F
(
t
)
d
t
m
1
formula
(
2
)
wherein v 1 represents the pre-collision speed of the dummy head, v′ 1 represents the post-collision speed of the dummy head, m 1 represents the mass of the dummy head, F(t) represents an impact force related to the time, and the change of the impact force meets a change trend of increasing first and then decreasing in the sine curve; and
the pre-collision speed and the post-collision speed of the rigid flat plate are both 0.
2. The method for predicting the dummy head injury during the automobile collision according to claim 1 , further comprising the following steps after calculating an injury value of the dummy head in each time interval according to the maximum contact force, and selecting the maximum injury value as a target injury value:
calling an injury level database, and judging an injury level to the dummy head according to the target injury value; the injury level database comprises a plurality of injury level ranges, and the injury level corresponding to each of the injury level ranges.
3. The method for predicting the dummy head injury during the automobile collision according to claim 2 , wherein total energy of the dummy head and the rigid flat plate before the start of the collision process and after the end of the collision process meets that: total kinetic energy before the start of the collision is equal to the sum of total kinetic energy after the end of the collision, energy lost due to Hertz contact, energy lost due to a shell body deformation, and energy lost due to the collision speeds.
4. The method for predicting the dummy head injury during the automobile collision according to claim 3 , wherein while calculating the maximum contact force F max of the dummy head and the rigid flat plate in the collision process in combination with the law of energy conservation and according to the first data set, the post-collision speed of the dummy head and the post-collision speed of the rigid flat plate, the maximum force borne in the Hertz contact and the maximum force borne in the shell body deformation are both equivalent to the maximum contact force F max borne in the collision process.
5. The method for predicting the dummy head injury during the automobile collision according to claim 4 , wherein the target injury value is represented by the following formula:
HIC
=
max
(
t
1
,
t
2
)
〈
1
(
t
2
-
t
1
)
3
/
2
[
∫
1
t
2
F
max
m
1
sin
(
π
t
T
p
)
dt
]
5
/
2
〉
formula
(
23
)
wherein HIC represents the target injury value, (t 1 , t 2 ) represents the time interval, t 1 and t 2 represent two endpoint moments of the time interval respectively, max(t 1 , t 2 ) represents that the time interval from t 1 to t 2 is selected to maximize the expression in the parentheses, m 1 represents the mass of the dummy head, and represents the duration of the collision process.
6. The method for predicting the dummy head injury during the automobile collision according to claim 3 , wherein the energy lost due to the Hertz contact is calculated according to the following formula:
E
H
=
2
5
k
H
·
Δ
x
H
5
2
formula
(
10
)
wherein E H represents the energy lost due to the Hertz contact, H represents the sum of deformation quantities of the dummy head and the rigid flat plate in Hertz contact in the collision process, and k H represents Hertz contact stiffness.
7. The method for predicting the dummy head injury during the automobile collision according to claim 3 , wherein the energy lost due to the shell body deformation is calculated according to the following formula:
E
sh
=
1
2
k
sh
·
Δ
x
sh
2
formula
(
13
)
wherein E sh represents the energy lost due to the shell body deformation, Δx sh represents a deformation quantity of a bending deformation of the dummy head, and k sh represents contact stiffness of the shell body deformation of the dummy head.
8. The method for predicting the dummy head injury during the automobile collision according to claim 3 , wherein the energy lost due to the collision speeds is calculated according to the following formula:
E
e
=
1
-
e
2
2
·
m
1
m
2
m
1
+
m
2
(
v
1
-
v
2
)
2
formula
(
15
)
wherein E e represents the energy lost due to the collision speeds, e represents a recovery coefficient, and m 2 represents the mass of the rigid flat plate.