Dummy bionic tibia structure for multi-dimensional impact human injury test

Abstract

The invention relates to a dummy bionic tibia structure for a multi-dimensional impact human injury test. Comprising a dummy tibia main body structure, a fixing cap, a fixing bolt, an elastic element and a polyurethane structural part, the dummy tibia main body structure is composed of two cylindrical steel tubes with the same inner diameter and outer diameter, the polyurethane structural part is dumbbell-shaped, a stepped through hole is formed in the middle of the polyurethane structural part, the stepped through holes in the two ends of the polyurethane structural part are in interference fit with fixing caps, and a closed cavity is formed in the polyurethane structural part; the section of each elastic element is in a C shape matched with the shape of the polyurethane structural part, the multiple elastic elements are arranged on the periphery of the polyurethane structural part, and the two ends of the polyurethane structural part and the two ends of each elastic element are connected with the ends of the two steel pipes of the dummy tibia main body structure through fixing bolts and fixing caps respectively. According to the invention, the response of the elastic section and the flexible section of the tibia under multi-dimensional impact is simulated, and the biological fidelity and accuracy are improved.

Description

Technical Field

[0001] The present invention belongs to the fields of automotive crash dummy technology and human injury assessment, and particularly relates to a dummy bionic tibia structure for multi-dimensional impact human injury testing. Background Art

[0002] In disasters involving vehicles, such as vehicle collisions, landmine explosions or helicopter crashes, it is crucial to accurately evaluate the injuries of the human tibia under impacts in different directions. In vehicle safety tests, crash dummies are used to replace humans to test the injuries after being impacted. The lower limbs of the human body are impacted in different directions by in-vehicle environmental components such as the floor, steering wheel, and automotive interior, and there is a high risk of tibia fracture. There is an urgent need for a dummy simulation tibia structure with high biological fidelity that considers multi-dimensional impacts.

[0003] Currently, the device used to simulate human test injuries is an automotive crash dummy. The tibia of the dummy is designed as a simple rigid cylindrical structure, and there are the following problems:

[0004] (1) The existing rigid cylindrical tibia structure is very different from the human tibia structure. After being impacted, the impact force transmission path in the tibia is very different from the actual situation.

[0005] (2) The existing rigid cylindrical tibia structure has different stiffness from human bones and skin. After being impacted, the responses of the tibia are different.

[0006] (3) The existing dummy tibia was not designed considering the biological fidelity of multi-dimensional impacts and is very different from the human body.

[0007] In summary, the existing dummy tibia structure has very low biological fidelity, is difficult to simulate the tibia response under multi-dimensional impacts, resulting in inaccurate test data and inaccurate injury assessment. Summary of the Invention

[0008] The purpose of the present invention is to provide a dummy bionic tibia structure for multi-dimensional impact human injury testing. By using a proposed method for designing the size and stiffness of an elastic element and a polyurethane structural member, combined with multi-dimensional impact boundaries, the design of a rigid-flexible combined dummy bionic tibia structure is realized, improving the biological fidelity of the dummy tibia and solving the problems of low biological fidelity of the dummy tibia, inability to simulate multi-dimensional impact responses, and inaccurate test data.

[0009] The technical solution to achieve the purpose of the present invention is: a dummy bionic tibia structure for multi-dimensional impact human injury testing, including a dummy tibia main structure, a fixing cap, fixing bolts, an elastic element, and a polyurethane structural member;

[0010] The dummy tibia main structure is composed of two cylindrical steel pipes with the same inner and outer diameters. The polyurethane structural member is in the shape of a "dumbbell", with a stepped through-hole opened in the middle. The stepped through-holes at both ends of the polyurethane structural member are press-fitted with fixing caps, and a sealed cavity is formed inside the polyurethane structural member; the elastic element has a cross-section in the shape of a "C" that matches the shape of the polyurethane structural member. Multiple elastic elements are arranged on the outer periphery of the polyurethane structural member. The two ends of the polyurethane structural member and the elastic element are respectively connected to the ends of the two steel pipes of the dummy tibia main structure through fixing bolts and fixing caps, so as to realize the connection of the two sections of the dummy tibia main structure.

[0011] Further, the cross-sectional shape of the polyurethane structural member is in the shape of a "dumbbell", that is, it is composed of a cylindrical section and an arc section connecting the two cylindrical sections. The stepped through-hole opened in the middle is composed of a circular hole with an inner diameter of r5 in the two cylindrical sections and a circular hole with an inner diameter of r6 in the arc section. The outer diameter of the cylindrical section is r4, and multiple through-holes with a diameter of d4 for fixing bolts to pass through are provided on the side wall of the cylindrical section. The outer peripheral groove of the arc section is a 1 / 2 circumferential "dumbbell" groove with a diameter of d5, and the length of the polyurethane structural member is r3.

[0012] Further, the dimensions of the polyurethane structural member satisfy the following relationships:

[0013] r3 = D + 4d4

[0014] r5 = 1 / 2r4

[0015] r6 = 1 / 2r5

[0016] The dimensions of the polyurethane structural member are calculated and determined according to the following formula:

[0017]

[0018] In the formula, D is the distance between the two cylindrical steel pipes of the dummy tibia main structure, G is the shear modulus of the polyurethane, J is the moment of inertia, K JT is the axial stiffness, K JS is the radial stiffness, and K JM is the torsional stiffness, E is the elastic modulus of the polyurethane, A is the designed cross-sectional area, and L is the designed total length.

[0019] Further, the distance D between the two cylindrical steel pipes of the dummy tibia main structure is determined by the following formula:

[0020]

[0021] θ y is the radian when the elastic element enters the plastic stage. The outer diameter of the cylindrical steel pipe is d1, and the inner diameter is d2, and they satisfy the following formula:

[0022] d2 = r4 + 2T

[0023] Where T is the thickness of the elastic element.

[0024] Furthermore, the elastic element has an up-and-down and left-and-right symmetric structure. There are through holes at the connections between both ends of the elastic element and the polyurethane structural member. The Young's modulus of the material used for the elastic element is E, and the yield limit is σ y , with a thickness of T. The elastic element is pre-bent. The radius of curvature at the bending vertex a2 is ρ0, and the bending radian is θ0, satisfying the following formula:

[0025]

[0026] Where H is the height of the C-shaped opening of the elastic element;

[0027] The radian θ of the elastic element entering the plastic stage y is calculated according to the following formula:

[0028]

[0029] The elastic element is divided into two side straight segments and a middle bending segment. The vertical stiffness of the straight segment is the elastic modulus E of the material itself. The length of one side straight segment is l1, and the bending stiffness K ZX is:

[0030]

[0031] The radius of curvature of the bending segment is ρ0, and the bending radian is θ0. The effective length l2 = ρ0θ0. Then the stiffness K of the bending segment ZW is:

[0032]

[0033] The overall stiffness K of the elastic element is:

[0034]

[0035] The width of the elastic element is set to a gradient width to achieve a third-order stiffness change. The first-order width b1 at both outermost sides, the third-order width b3 at the center, and the second-order width b2 between the first-order width b1 and the third-order width ensure that the center position of the elastic element is the bending deformation point after impact. The width meets the following requirements:

[0036] b1 > b2 > b3.

[0037] Furthermore, the bending radian θ0 of the elastic element is π / 2, and the thickness T of the elastic element is 1 - 1.5 mm.

[0038] Furthermore, the number of elastic elements is 4, which are evenly distributed around the radial circumference of the polyurethane structural member. And during installation, the through holes of the elastic elements correspond to the through holes of the polyurethane structural member.

[0039] Further, the fixing cap has a "T"-shaped cross-sectional shape, with a small-end diameter of r1 and a large-end diameter of r2. A round hole with a diameter of d3 is provided at the small-end diameter. The dimensions of the fixing cap satisfy:

[0040] r1 = r5

[0041] r2 = d2.

[0042] Further, the fixing bolt is a fully threaded screw rod with a length of L b , with a thread diameter of R; the diameter of the fixing bolt is not less than 6 mm, and the length L b satisfies the following dimensions:

[0043] L b ≤ 1 / 2 * d1

[0044] d3 = R.

[0045] Further, the fixing cap is made of 6061 aluminum, the polyurethane structural member is made of PU-80A polyurethane, the fixing bolt is made of 40C, and the main structural material of the dummy tibia is 45# steel.

[0046] Compared with the prior art, the present invention has the following remarkable advantages:

[0047] The dummy bionic tibia structure for multi-dimensional impact human injury testing provided by the present invention can simulate the response of the human tibia under impacts in the X and Y directions, provide a small deformation space and deformation control, and improve the biological fidelity;

[0048] The dummy bionic tibia structure for multi-dimensional impact human injury testing provided by the present invention can simulate the response of the human tibia under impact in the Z direction, provide a third-order non-linear simulation of the elastic section and the flexible section, and improve the biological fidelity;

[0049] The dummy bionic tibia structure for multi-dimensional impact human injury testing provided by the present invention, as a component, can be conveniently replaced, has a low cost, and is easy to maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Overall schematic diagram of the dummy bionic tibia structure of the present invention; (a) is a three-dimensional view, and (b) is a cross-sectional view.

[0051] Figure 2 Schematic diagram of the C-shaped elastic element of the present invention; (a) is a right side view, (b) is an enlarged view of the inflection point in (a), (c) is a front view, and (d) is a left side view.

[0052] Figure 3 Schematic diagram of the fixing cap structure of the present invention; (a) is a three-dimensional view, and (b) is a front view.

[0053] Figure 4 Schematic diagram of the polyurethane buffer structure of the present invention; where (a) is a three-dimensional view and (b) is a cross-sectional view.

[0054] Description of the reference numerals:

[0055] 1 - dummy tibia main body structure, 2 - fixing cap, 3 - fixing bolt, 4 - elastic element, 5 - polyurethane structure member. Detailed implementation manners

[0056] The present invention will be further described in detail below with reference to the accompanying drawings.

[0057] As Figures 1-4 shown, the purpose of the present invention is to invent a dummy bionic tibia structure, which can improve the bio - fidelity of the tibia structure under multi - dimensional impacts, simulate the response state of a real human body, and obtain real, accurate and effective data. Thus, a dummy bionic tibia structure for multi - dimensional impact human injury testing is provided. It is a flexible structure. By setting the size and material characteristics of the structure, it has different stiffnesses in different directions, simulating the response of the tibia under impacts in different directions, and greatly improving the accuracy of tibia injury test data.

[0058] The dummy bionic tibia structure includes a dummy tibia main body structure 1, an elastic element 4, a polyurethane structure member 5, a fixing cap 2 and a fixing bolt 3;

[0059] The dummy tibia main body structure 1 is a structure already existing in the existing dummy. As Figure 1 shown, the outer diameter d1 and the inner diameter d2 are consistent with the existing structure; the distance between the upper and lower ends of the dummy tibia structure is D, and the distance D satisfies:

[0060]

[0061] θ y is the radian when the elastic element enters the plastic stage, and L is the designed total length

[0062] The bionic structure of the elastic element 4 is as Figure 3 shown. The cross - sectional shape is "C" - shaped. The Young's modulus of the material used is E, the yield limit is σ y , and the thickness is T, realizing the simulation of the elastic - segment impact response in the axial direction and providing the stiffness in the cross - section direction;

[0063] The elastic element 4 is pre - bent. The radius of curvature at the bending point a2 is ρ0, and the bending radian is θ0. To achieve the cooperation with the polyurethane bionic structure and facilitate the bending control, θ0 is set to π / 2, and the thickness T = 1 - 1.5 mm. Then:

[0064] ρ0 = H / 2

[0065] The radian when the elastic element enters the plastic stage is θy , can be calculated and obtained:

[0066]

[0067] The width of the elastic element 4 is set to a gradient width to achieve a third-order stiffness change. The first-order width is b1, the second-order width is b2, and the third-order width is b3, ensuring that the center position of the elastic element after impact is the bending deformation point. The width meets the following requirements:

[0068] b1 = b2 + 2mm = b3 + 4mm

[0069] The stiffness of the elastic element 4 can be designed. The elastic element 4 is divided into a straight section and a bent section. The vertical stiffness of the straight section is related to the elastic modulus E of the material itself, and the length of the straight section is l1 and the bending stiffness is K ZX is:

[0070]

[0071] The stiffness of the bent section needs to consider the bending and torsion coupling effects. The radius of curvature of the bent section is ρ0, the bending radian is θ0, and the effective length l2 = ρ0θ0, then the stiffness K ZW is:

[0072]

[0073] The overall stiffness K of the elastic element is:

[0074]

[0075] The polyurethane structural member 5 is as Figure 4 shown, with a "dumbbell" shape, a length of r3, and a diameter of r4; through holes with a diameter of d4 are provided at both ends, a "dumbbell" groove with a diameter of d5 is provided in the middle, round holes with a diameter of r5 are provided at the cylindrical parts at both ends of the end face, and round holes with a diameter of r6 are provided at the position of the middle "dumbbell" groove to achieve the simulation of the impact response of the flexible section in the axial and cross-sectional directions;

[0076] The dimensions of the polyurethane structural member 5 meet:

[0077] r3 = D + 4d4

[0078] d4 = d3 = R

[0079] r4 = d2 - 2T

[0080] d5 = ρ0

[0081] r5 = 1 / 2r4

[0082] r6 = 1 / 2r5

[0083] The stiffness of the polyurethane structural member 5 is divided into axial stiffness K JT , radial stiffness K JS and torsional stiffness K JM , and the calculation formulas are as follows:

[0084]

[0085] In the formula, E is the elastic modulus of polyurethane, A is the cross-sectional area, and L is the total designed length, that is

[0086]

[0087] In the formula, G is the shear modulus of polyurethane and J is the moment of inertia.

[0088] The number of bionic structures of the elastic element 4 is set to 4, which are evenly distributed around the circumference of the polyurethane structural member 5 in the radial direction to ensure that the through holes of the elastic element 4 correspond to the through holes of the polyurethane structural member 5.

[0089] The fixing cap 2 is as Figure 2 shown, and its cross-sectional shape is "T"-shaped. The diameter of the small end is r1, and the diameter of the large end is r2. A round hole with a diameter of d3 is provided at the diameter of the small end. The dimensions of the fixing cap satisfy:

[0090] r1 = r5

[0091] r2 = d2

[0092] d3 = R

[0093] The fixing bolt 3 is a full-threaded screw with a length of L b , and the thread diameter is R; the diameter of the fixing bolt is not less than 6 mm, and the length L b dimensions satisfy:

[0094] L b ≤ 1 / 2 * d1

[0095] Under the impact loads in the X and Y radial directions of the bionic structure of the dummy, the four groups of bionic structures of the elastic elements provide a small deformation space, and the mechanical properties of the human bones are simulated in the elastic section. The polyurethane bionic structure realizes the deformation control function of the bionic structure of the elastic element.

[0096] Under the impact load in the Z radial direction of the bionic structure of the dummy, the four groups of bionic structures of the elastic elements show elastic bending at the central position. The three-gradient widths of the bionic structures of the elastic elements are set to realize the simulation of the non-linear stiffness in the elastic section; there is a sealed cavity inside the polyurethane bionic structure set, and air oscillation occurs during the deformation process, forming a "damping" effect to realize the simulation of the non-linear stiffness in the flexible section.

[0097] The bionic structure of the dummy realizes the bionic simulation of the human tibia under multi-dimensional impacts through the mutual cooperation between its components, improves the biological fidelity, and ensures the effectiveness and accuracy of the human injury test data.

[0098] Embodiment

[0099] A bionic tibia structure of a dummy for multi-dimensional impact human injury test, the tibia structure includes:

[0100] The bionic structure of the elastic element is as Figure 3 shown, with a cross-sectional shape of "C", made of stainless steel 304L, and the manufacturing process includes pressing, cutting, trimming and bending; the thickness of the elastic element is t = 1.5 mm, and the width is set to a gradient width to achieve a third-order stiffness change, b1 is 10 mm, b2 is 8 mm, and b1 is 6 mm; at the same time, ensure that the center position of the elastic element is the bending deformation point after impact.

[0101] The bionic structure of polyurethane is as Figure 4 shown, with a shape of "dumbbell", made of PU-80A polyurethane, with a diameter of 40 mm and a length of 50 mm; a circular groove with a radius of 8 mm is provided in the middle of the bionic structure of polyurethane to realize the cooperation with the bionic structure of the elastic element; a gradient diameter round hole is provided at the axis of the bionic structure of polyurethane, the diameter of the round holes at both ends is 20 mm, the length is 17 mm, and the center diameter is 10 mm; 6 mm through holes are provided at both ends.

[0102] The number of bionic structures of the elastic element is set to 4, which are evenly distributed around the radial direction of the bionic structure of polyurethane, ensuring that the through holes of the bionic structure of the elastic element correspond to the through holes of the bionic structure of polyurethane.

[0103] The fixing cap is as Figure 2 shown, made of 6061 aluminum, with a cross-sectional shape of "T", the large end diameter is 40 mm, the length is 10 mm, the small end diameter is 20 + 0.1 mm, and the length is 12 mm; four 6 mm threaded holes are provided at the small end.

[0104] The number of fixing caps is set to 2, which are distributed at both ends of the bionic structure of polyurethane. The fixing caps are in interference fit with the bionic structure of polyurethane to ensure that the provided through holes correspond.

[0105] The bionic structure of the elastic element is placed between the dummy tibia structure and the bionic structure of polyurethane. Use an M6×27 mm half-thread bolt to sequentially pass through the dummy tibia structure, the bionic structure of the elastic element and the bionic structure of polyurethane, and cooperate with the threaded holes of the fixing cap to realize the assembly of the bionic structure of the dummy.

Claims

1. A bionic tibial structure for multi-dimensional impact human injury testing, characterized in that: It comprises a dummy tibia main structure (1), a fixing cap (2), a fixing bolt (3), an elastic element (4) and a polyurethane structural part (5); The dummy tibia main structure (1) is composed of two sections of cylindrical steel pipes with the same inner and outer diameters. The polyurethane structural member (5) is in the shape of a "dumbbell" with a stepped through hole in the middle. The stepped through holes at both ends of the polyurethane structural member (5) are interference-fitted with the fixing caps (2) to form a closed cavity inside the polyurethane structural member (5). The cross section of the elastic element (4) is in the shape of a "C" that matches the shape of the polyurethane structural member (5). A plurality of elastic elements (4) are arranged on the periphery of the polyurethane structural member (5). The ends of the polyurethane structural member (5) and the elastic element (4) are connected to the ends of the two sections of the steel pipes of the dummy tibia main structure (1) through fixing bolts (3) and fixing caps (2) respectively, thereby realizing the connection of the two sections of the dummy tibia main structure (1).

2. The bionic tibial structure of a dummy according to claim 1, characterized in that: The cross-sectional shape of the polyurethane structural member (5) is a "dumbbell" type, that is, it is composed of a cylindrical section and an arc section connecting the two cylindrical sections. The stepped through hole opened in the middle is composed of circular holes with an internal diameter of r5 in the two cylindrical sections and a circular hole with an internal diameter of r6 in the arc section. The outer diameter of the cylindrical section is r4. The side wall of the cylindrical section is provided with a plurality of through holes with a diameter of d4 for the fixing bolts to pass through. The outer peripheral groove of the arc section is a 1 / 2 circumference "dumbbell" groove with a diameter of d5. The length of the polyurethane structural member (5) is r3.

3. The bionic tibial structure of a dummy according to claim 2, characterized in that: The dimensions of polyurethane structural parts satisfy the following relationship: r3=D+4d4 r5＝1 / 2r4 r6＝1 / 2r5 The size of the polyurethane structural parts is determined by the following calculation formula: Where D is the distance between the two cylindrical steel tubes of the main structure of the dummy tibia, G is the shear modulus of polyurethane, J is the moment of inertia, and K is JT is the axial stiffness, K JS is the radial stiffness and K JM is the torsional stiffness, E is the elastic modulus of polyurethane, A is the designed cross-sectional area, and L is the designed total length.

4. The bionic tibial structure of a dummy according to claim 3, characterized in that: The distance D between the two cylindrical steel tubes of the dummy tibia main structure is determined by the following formula: θ y is the arc of the elastic element entering the plastic stage. The outer diameter of the cylindrical steel tube is d1, the inner diameter is d2, and the following formula is satisfied: d2=r4+2T Where T is the thickness of the elastic element.

5. The bionic tibial structure of a dummy according to claim 4, characterized in that: The elastic element (4) is a vertically and horizontally symmetrical structure. Through holes are provided at the connection points between the two ends of the elastic element (4) and the polyurethane structural member (5). The Young's modulus of the material used in the elastic element (4) is E, and the yield limit is σ y , thickness is T, the elastic element is pre-bent, the curvature radius at the bending vertex a2 is ρ0, the bending arc is θ0, and the following formula is satisfied: Wherein, H is the height of the C-shaped opening of the elastic element; The arc angle θ of the elastic element entering the plastic stage y Calculated according to the following formula: The elastic element is divided into two straight sections on both sides and a bent section in the middle. The vertical stiffness of the straight section is the elastic modulus E of the material itself. The length of the straight section on one side is l1, and the bending stiffness is K. ZX for: The curvature radius of the bending section is ρ0, the bending arc is θ0, and the effective length l2 = ρ0θ0, then the stiffness K of the bending section is ZW for: The overall stiffness K of the elastic element is: The width of the elastic element is set to a gradient width to achieve a third-order stiffness change, with the first-order width b1 on the two sides, the third-order width b3 in the center, and the second-order width b2 between the first-order width b1 and the third-order width, ensuring that the center position of the elastic element is the bending deformation point after impact, and the width meets the following requirements: b1>b2>b3.

6. The bionic tibial structure of a dummy according to claim 5, characterized in that: The bending arc θ0 of the elastic element is π / 2, and the thickness T of the elastic element is 1-1.5 mm.

7. The bionic tibial structure of a dummy according to claim 6, characterized in that: The number of elastic elements is 4, which are evenly distributed around the polyurethane structural component (5) in radial direction, and during installation, the through holes of the elastic elements correspond to the through holes of the polyurethane structural component (5).

8. The bionic tibial structure of a dummy according to claim 7, characterized in that: The cross-sectional shape of the fixing cap (2) is "T" shaped, the diameter of the small end is r1, the diameter of the large end is r2, and a circular hole with a diameter of d3 is provided in the diameter of the small end. The dimensions of the fixing cap (2) satisfy: r1＝r5 r2＝d2。 9. The bionic tibial structure of a dummy according to claim 8, characterized in that: The fixing bolt (3) is a full-thread screw with a length of L. b The thread diameter is R; the fixing bolt (3) has a diameter of not less than 6 mm and a length of L b Size meets: THE b ≤1 / 2*d1 d3=R.

10. The bionic tibial structure of a dummy according to claim 9, characterized in that: The fixing cap (2) is made of 6061 aluminum, the polyurethane structural member (5) is made of PU-80A polyurethane, the fixing bolt (3) is made of 40C, and the dummy tibia main structure (1) is made of 45# steel.

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