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

Abstract

The invention relates to a dummy head bionic structure for a multi-dimensional impact human body injury test. Comprising a dummy skull inner shell, a rigid bottom plate, a central vertical rubber column, a circumferential shearing rubber column, a rigid guide core, a rigid platform and a head acceleration sensor. The head acceleration sensor is mounted on the rigid platform and is aligned with the brain center in height; the central vertical rubber column is arranged at the central position between the rigid bottom plate and the rigid platform; the plurality of circumferential shearing rubber columns are uniformly arranged along the circumferential direction of the central vertical rubber column; the rigid guide core is arranged in the circumferential shearing rubber column in a penetrating manner; the lower section of the rigid guide core is in interference fit with the rigid bottom plate, and the upper section is in clearance fit with the rigid platform; the central vertical rubber column and the circumferential shearing rubber columns are connected with the rigid bottom plate and the rigid platform through structural adhesives. According to the method, equivalent simulation of main modal characteristics of a skull-brain system is realized, the biological fidelity of head acceleration measurement is improved, and the accuracy of brain injury criterion calculation is improved.

Description

Technical Field

[0001] This invention belongs to the field of automobile collision dummies and human injury assessment, specifically relating to a biomimetic structure for a dummy head used in multidimensional impact human injury testing. Background Technology

[0002] In vehicle-related disasters, such as frontal or side collisions, detonation of landmines or improvised explosive devices,

[0003] In scenarios such as helicopter or armored vehicle crashes, accurately assessing head injuries under multi-directional impacts and rotational motions is crucial. In vehicle safety testing and protection assessments, crash dummies are typically used to replace real human subjects, using the dummy's head acceleration and impact response to infer the risk of brain damage. However, in real-world conditions, the human head not only experiences multi-directional impacts from the steering wheel, headliner, seat back, and floor rebound, but also experiences significant angular acceleration and relative motion between the skull and brain tissue. Traditional dummy head structures differ significantly from real human heads, making it difficult to realistically reproduce the mechanisms of brain injury. Therefore, there is an urgent need for a simulated head structure with higher biofidelity under multi-dimensional impact conditions.

[0004] Currently, the main device used to simulate human injury testing is the car crash test dummy. The dummy's head usually uses a rigid or near-rigid hollow shell structure, with a rigid accelerometer or metal frame inside to house the accelerometer sensor. This presents the following problems:

[0005] (1) Existing dummy heads mostly adopt simplified rigid skull shell and internal rigid accelerometer structure, which are significantly different from the real human body’s multi-layered structure of “skull-brain tissue-cerebrospinal fluid”. The transmission path and energy distribution of impact load inside the head are significantly different from the actual human body.

[0006] (2) In existing dummy heads, the accelerometer is usually fixed directly to the skull shell by a rigid connection. The overall stiffness is much higher than the combined equivalent stiffness of the human scalp, skull and brain tissue. During impact, the high-frequency vibration is almost unfiltered and directly acts on the sensor, resulting in a large deviation between the measured linear acceleration and angular acceleration and the mechanical response of the real head.

[0007] (3) Existing dummy heads focus more on overall geometric shape and mass inertia matching in the initial design, without fully considering the bio-realism under multi-directional impact, especially with large angular acceleration and complex contact conditions. It is difficult to reasonably characterize the relative motion between the skull and brain tissue and the dynamic response characteristics related to injury criteria.

[0008] In summary, existing dummy head structures have low biofidelity in terms of internal mechanical structure and sensor installation methods, making it difficult to accurately simulate the dynamic response of a real human head under multidimensional impact conditions. This results in discrepancies between the head acceleration data obtained in experiments and the actual brain injury risk, leading to inaccurate injury assessment results. There is an urgent need to improve the dummy head structure and acceleration measurement unit. Summary of the Invention

[0009] The purpose of this invention is to provide a biomimetic structure for a dummy head used in multidimensional impact human injury testing.

[0010] The technical solution to achieve the purpose of this invention is: a dummy head bionic structure for multidimensional impact human injury testing, characterized in that it includes a dummy skull inner shell, a rigid base plate, a central vertical rubber column, a circumferential shear rubber column, a rigid guide core, a rigid platform, and a head acceleration sensor.

[0011] The rigid base plate is rigidly fixed to the inner wall of the dummy skull shell; the head accelerometer is mounted on the rigid platform at a height aligned with the center of the brain; a central vertical rubber column is positioned at the center between the rigid base plate and the rigid platform to provide vertical support rigidity; several circumferential shear rubber columns are evenly arranged around the central vertical rubber column to withstand shear displacements generated by horizontal impacts and rotational motions; the circumferential shear rubber columns have annular cross-sections, with a rigid guide core inserted inside each column and a radial gap between them; the lower section of the rigid guide core is interference-fitted to the rigid base plate, while the upper section is clearance-fitted to the rigid platform; the central vertical rubber column, the circumferential shear rubber column, the rigid base plate, and the rigid platform are connected by structural adhesive.

[0012] Furthermore, the lower end of the rigid guide core is interference-fitted with the countersunk hole on the rigid base plate through the retaining section, and the upper end of the rigid guide core is guided by the guide section and the guide hole of the rigid platform through the gap.

[0013] The rigid base plate and rigid platform are provided with shallow grooves that cooperate with the central vertical rubber column and the circumferential shear rubber column. The bottom surface and side wall of the central vertical rubber column, the circumferential shear rubber column and the cooperating shallow groove are bonded together.

[0014] Furthermore, the height of the central vertical rubber column Determined by the following formula:

[0015] ,

[0016] ,

[0017] In the formula, The target height when the accelerometer is in the center of the brain. For rigid base plate thickness, For the thickness of the rigid platform;

[0018] Equivalent vertical stiffness of the central vertical rubber column Determined according to the following formula:

[0019] ,

[0020] In the formula, For the target's inherent frequency, For equivalent quality, The elastic modulus of the central vertical rubber column material. The cross-sectional area of ​​the central vertical rubber column;

[0021] Central vertical rubber column cross-sectional dimensions It can be obtained from the following formula:

[0022] ,

[0023] .

[0024] Furthermore, the circumferential shear rubber column has a radially layered composite structure, consisting of a first modulus rubber layer, a second modulus transition layer, and a third modulus rubber layer from the inside out. The shear stiffness of a single shear rubber column is determined by the following formula:

[0025]

[0026]

[0027] in, The shear stiffness of the first modulus rubber layer. The shear stiffness of the second modulus transition layer. The shear stiffness of the third modulus rubber layer. The total shear stiffness of a shear rubber column;

[0028] The dimensions of a single shear rubber column are determined by the following formula:

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] In the formula, The inner diameter of the shear rubber column is given. The diameter of the rigid guide core. This refers to the radial gap between the rigid guide core and the shear rubber column. The outer diameter of the shear rubber column. For the first The equivalent area of ​​the layer For the first The elastic modulus of the layer, The height of the shear rubber column;

[0036] The aspect ratio of a single shear rubber column and the minimum thickness of each layer are determined by the following formula:

[0037]

[0038]

[0039] In the formula, The aspect ratio is height to diameter. The experience value is 4. For the first The thickness of the layer.

[0040] Furthermore, the dimensions of the rigid guide core are determined by the following formula:

[0041]

[0042]

[0043]

[0044] In the formula, The length of the lower retaining section. The length of the working section. The length of the upper guide section. The diameter of the rigid guide core. The height of the guide core.

[0045] Furthermore, the parameters of the rigid guide core are determined by the following formula:

[0046]

[0047]

[0048]

[0049]

[0050] In the formula, The cross-sectional area of ​​the guide core. This refers to the shear displacement during operation. Shear strain during operation This represents the maximum permissible shear displacement during operation. This represents the maximum allowable shear strain during operation.

[0051] Furthermore, the dimensions of the countersunk hole on the rigid base plate that mates with the rigid guide core satisfy the following formula:

[0052]

[0053]

[0054]

[0055] In the formula, The diameter of the lower end retaining section of the guide core, Interference quantity The over-excess coefficient, The diameter of the countersunk hole;

[0056] depth of countersunk hole interference fit section Determined by the following formula:

[0057]

[0058]

[0059]

[0060] In the formula, The contact area between the lower end of the guide core retaining section and the countersunk hole. The maximum axial force that the guide core can withstand. The average shear stress on the interface of the interference fit section. This represents the allowable shear stress of the material.

[0061] Furthermore, the dimensions of the guide hole on the rigid platform are determined by the following formula:

[0062]

[0063] In the formula, For axial clearance, The depth of the guide hole;

[0064] Bending strength of the guide core under extreme conditions of acceleration exceeding 50g and instantaneous impact velocity exceeding 10m / s. Determined by the following formula:

[0065]

[0066]

[0067] In the formula, This represents the maximum shear force that the guide core can withstand under extreme working conditions. The yield strength of the material. For safety factor;

[0068] diameter of the guide hole Determined according to the following formula:

[0069]

[0070] In the formula, The radial clearance between the guide hole and the guide section of the rigid guide core.

[0071] Furthermore, the bottom surface bonding area of ​​a single circumferential shear rubber column and the shallow groove bonding surface. for:

[0072]

[0073] The depth of a single slot is Sidewall bonding area for:

[0074]

[0075] The depth of a single slot is determined by the following formula:

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] In the formula, This represents the total bonding area. This represents the maximum force transmitted to the bonding interface from a single rubber column under extreme load. Minimum bonding area, This represents the allowable shear stress of the structural adhesive. This represents the minimum depth of a single slot.

[0082] A design method for the above-mentioned biomimetic structure of a dummy head includes the following steps:

[0083] S1: Establish a single-degree-of-freedom equivalent model of the "skull-soft connection-accelerometer block" and determine the equivalent mass. Target natural frequency With damping ratio ;

[0084] S2: Determine the equivalent stiffness of the flexible connection based on the target natural frequency and damping ratio. With equivalent damping ;

[0085] S3: Determine the equivalent vertical stiffness of the central vertical rubber column based on the equivalent stiffness. and cross-sectional dimensions;

[0086] S4: Determine the total shear stiffness of the circumferential shear rubber column based on the horizontal shear requirements. And the effective area and outer diameter of a single shear rubber column;

[0087] S5: Determine the diameter, length, and radial clearance between the rigid guide core and the shear rubber post. ;

[0088] S6: Verify the shear strength and bending strength of the guide core under extreme conditions of acceleration exceeding 50g and instantaneous impact velocity exceeding 10m / s;

[0089] S7: Design the interference fit hole diameter and interference fit section depth of the countersunk hole in the rigid base plate;

[0090] S8: Determine the slot depth based on the bond bearing capacity check.

[0091] Compared with the prior art, the significant advantages of this invention are:

[0092] (1) The present invention sets up a designable biomimetic soft connection system between the inner shell of the skull and the acceleration measurement unit, so that the measurement unit and the skull form a dynamic coupling relationship that is closer to the "skull-soft tissue" of the human head, which is conducive to improving the biofidelity and effectiveness of multidimensional impact test data.

[0093] (2) The present invention adopts a combined soft connection unit of “central vertical rubber column + circumferential shear rubber column”: the central vertical rubber column mainly undertakes vertical support and buffer rebound, and the circumferential shear rubber column mainly undertakes horizontal impact and shear deformation caused by rotation, thereby realizing comprehensive bionics and energy dissipation of vertical, horizontal and rotational responses, and improving the response characterization capability under multidimensional impact and rotational coupling conditions.

[0094] (3) The circumferential shear rubber column of the present invention adopts a radial layered composite structure (first modulus layer / second transition layer / third modulus layer), so that materials of different moduli participate in the stress step by step during shear deformation, forming a progressively hardened equivalent shear mechanical response, which is closer to the nonlinear shear characteristics of real soft tissue; in the small deformation stage, it is beneficial to filter out unwanted high-frequency components, and in the large deformation stage, it is beneficial to improve the load margin and the ability to resist failure.

[0095] (4) The present invention provides a rigid guide core inside the circumferential shear rubber column and presets a radial gap between the guide core and the circumferential shear rubber column: Under small displacement conditions, the guide core and the rubber column do not contact each other, so that a rigid force transmission path is not formed, which is beneficial to reduce the direct coupling of rigid impact to the sensor; Under strong impact or abnormal conditions, when the deformation approaches the limit, the rubber column contacts the guide core, the guide core shares the load and plays a limiting role for large deformation, which can suppress the risk of excessive shearing, instability and bonding interface damage of the circumferential shear rubber column, and improve the safety, stability and reusability of the structure.

[0096] (5) The present invention adopts a clearance guide fit between the upper end of the guide core and the guide hole of the rigid platform, and sets a preset axial clearance so that the guide core does not make a dead contact during the small displacement stage, reducing unwanted rigid constraints and friction interference, which is conducive to improving the stability of the working process of the circumferential shear rubber column and the consistency of test data.

[0097] (6) The lower end of the guide core of the present invention is preferably connected to the rigid base plate by countersunk hole interference fit, which can provide a stable assembly reference and mechanical transmission reference, reduce the risk of loosening and drifting under multiple impact loads, and improve the structural connection reliability and batch consistency.

[0098] (7) The present invention preferably provides countersunk holes and annular groove structures between the rubber column and the rigid base plate / rigid platform, and can be used with structural adhesive to form a more sufficient geometric holding and bonding area, improve the interface peel resistance and connection strength, reduce the probability of rubber column debonding, loosening or interface damage under impact load, thereby improving the overall structure durability and engineering feasibility.

[0099] (8) This invention not only provides a biomimetic structure, but also a matching parametric design method: based on the “skull-soft connection-dynamic model”, the equivalent stiffness and damping of the soft connection unit can be determined with the target natural frequency and damping ratio as design constraints. Furthermore, key structural parameters such as the central vertical rubber column, circumferential shear rubber column and guide core gap, strength and interference fit can be calculated, so that the structural design is transformed from experience trial and error into a calculable and reproducible process, which is convenient for rapid adaptation and optimization under different dummy platforms and different test requirements.

[0100] (9) The overall structure of the present invention has a high degree of modularity. The rigid base plate can be fixed to the inner shell of the skull with screws. The soft connection unit and sensor installation method are clear, which makes it easy to integrate, disassemble and maintain on the existing dummy head structure. It has good engineering application value. Attached Figure Description

[0101] Figure 1 A schematic diagram of the overall structure of the dummy head of the present invention; wherein (a) is a three-dimensional view and (b) is a cross-sectional view.

[0102] Figure 2 A schematic diagram of the soft connection unit structure of the present invention; wherein (a) is the front view and (b) is the right view.

[0103] Figure 3 A schematic diagram of the circumferential shear rubber column structure of the present invention; wherein (a) is Figure 2 (b) is a BB-direction sectional view, and (b) is a sectional view of a single shear rubber column.

[0104] Figure 4 Figure 2 (a) Sectional view along the AA direction.

[0105] Explanation of reference numerals in the attached figures:

[0106] 1-Inner shell of the dummy skull, 2-Rigid base plate, 3-Central vertical rubber column, 4-Circumferential shear rubber column, 5-Rigid guide core, 6-Rigid platform, 7-Head accelerometer. Detailed Implementation

[0107] The present invention will now be described in further detail with reference to the accompanying drawings.

[0108] This invention proposes a dummy bionic head acceleration measurement structure and design method for multidimensional impact human injury testing. A designable soft connection system is introduced between the dummy skull shell and the acceleration measurement unit, allowing the main modal characteristics of the measurement unit to match the equivalent dynamic characteristics of the human head under multi-directional impact, thereby improving the effectiveness and repeatability of acceleration measurement data. The structure includes a dummy skull inner shell, a rigid base plate, a central vertical rubber column, a circumferential shear rubber column, a rigid platform, and a head acceleration sensor.

[0109] The main structure of the dummy's head consists of a rigid skull and a rigid base plate. The rigid base plate is rigidly fixed to the inner wall of the skull with screws and structural adhesive, serving as the lower base for the flexible connecting blocks. A flexible connecting unit is installed between the rigid base plate and the rigid platform. This unit consists of a central vertical rubber column and several circumferential shear rubber columns. The central vertical rubber column is located at the center of the structure, providing the main vertical support stiffness. The circumferential shear rubber columns are evenly distributed around the central vertical rubber column, with their lower ends fixed to the rigid base plate and the rigid platform, respectively, to withstand the shear displacement generated by the head during horizontal impacts and rotational movements. The circumferential shear rubber columns adopt a radially layered composite structure with an internal rigid guide core. The lower end of the rigid guide core is fixed to the rigid base plate, and the upper end is inserted into a guide hole on the rigid platform, with axial and radial gaps pre-set between the hole walls. An accelerometer is installed on the rigid platform, with its center of mass aligned with the geometric center of the skull. The rubber columns are geometrically locked to the base plate or platform through countersunk holes and annular grooves, thus achieving a biomimetic flexible connection between the accelerometer and the skull.

[0110] In the biomimetic soft connection system, the "skull-soft connection-accelerometer block" is simplified into a single-degree-of-freedom system, and its dynamic equation is:

[0111]

[0112] In the formula The equivalent mass of the accelerator block, This is the equivalent viscous damping coefficient. The equivalent stiffness of the flexible connection, For the equivalent damping of the soft connection, The input is for the local displacement of the skull, while This is the displacement output of the accelerometer block.

[0113] For the excitation base, its transfer function is:

[0114]

[0115] Furthermore, the target damping ratio and natural frequency are defined as follows:

[0116]

[0117] system stiffness and damping Determined by the following formula:

[0118]

[0119]

[0120] The static deformation of the system is determined by the following formula:

[0121]

[0122] Its acceleration transfer ratio can be determined by the following formula:

[0123]

[0124]

[0125] Furthermore, based on the system's target inherent frequency and equivalent quality The stiffness of the central vertical rubber column can be determined by the following formula:

[0126]

[0127] In the formula, The equivalent vertical stiffness of the central vertical rubber column. For cross-sectional area, The height of the central vertical rubber column, This is the elastic modulus of the rubber material.

[0128] Furthermore, the equivalent cross-sectional area of ​​the central vertical rubber column can be determined by the following formula:

[0129]

[0130] Furthermore, the height of the central vertical rubber column It can be determined by the following formula:

[0131]

[0132]

[0133] In the formula, The target height when the accelerometer is in the center of the brain. For rigid base plate thickness, The thickness is the rigid platform thickness.

[0134] Furthermore, the stiffness of the central vertical rubber column and height dimensions Once determined, the cross-sectional dimensions It can be obtained from the following formula:

[0135]

[0136]

[0137]

[0138] A central vertical rubber column is positioned in the center of the structure to provide the main vertical support stiffness, thereby achieving vertical buffering and rebound of the head under compression conditions.

[0139] Furthermore, the circumferential shear rubber columns are evenly arranged around the central vertical rubber column, and their upper and lower ends are fixedly connected to the rigid base plate and the rigid platform, respectively, to withstand the shear displacement generated by the head during horizontal impact and rotational motion.

[0140] Furthermore, the total shear stiffness of the circumferential shear rubber column can be determined by the following formula:

[0141]

[0142] in, The total shear stiffness of the multiple circumferential shear rubber columns. This represents the number of circumferential shear rubber columns. For the first Shear stiffness of a rubber column.

[0143] Furthermore, to reflect the nonlinear mechanical properties of brain tissue during shear deformation, the circumferential shear rubber column adopts a radially layered composite structure, with a first modulus rubber layer, a second modulus transition layer, and a third modulus rubber layer sequentially arranged from the inside out. Each layer participates in the stress distribution step by step during shearing, thereby constructing a progressive hardening shear response similar to that of human soft tissue.

[0144] Furthermore, the shear stiffness of a single shear rubber column can be determined by the following formula:

[0145]

[0146]

[0147] in, The shear stiffness of the first modulus rubber layer. The shear stiffness of the second modulus transition layer. The shear stiffness of the third modulus rubber layer. This represents the total shear stiffness of a shear rubber column.

[0148] Furthermore, the dimensions of a single shear rubber column can be determined by the following formula:

[0149]

[0150]

[0151]

[0152]

[0153]

[0154]

[0155] In the formula, The inner diameter of the shear rubber column is given. The diameter of the rigid guide core. This refers to the radial gap between the rigid guide core and the shear rubber column. The outer diameter of the shear rubber column. For the first The equivalent area of ​​the layer For the first The elastic modulus of the layer, For height.

[0156] Furthermore, to ensure the stability of the shear rubber column, its height-to-diameter ratio and the minimum thickness of each layer are determined by the following formula:

[0157]

[0158]

[0159] In the formula, The aspect ratio is height to diameter. The experience value is 4.

[0160] Furthermore, the dimensions of the rigid guide core can be determined by the following formula:

[0161]

[0162]

[0163]

[0164] In the formula, The length of the lower retaining section. The length of the working section. The length of the upper guide end. The diameter of the rigid guide core.

[0165] Furthermore, the lower tenon structure of the rigid guide core is fixedly connected axially through the corresponding tenon hole structure on the rigid base plate, so that the lower end of the guide core is constrained relative to the rigid base plate in axial displacement and rotation direction, forming a stable mechanical reference.

[0166] Furthermore, there is a radial gap between the middle section of the guide core and the rubber post. Under small displacement impact conditions, there is no contact between the rubber column and the guide core; when the strong impact load or abnormal conditions cause the column deformation to approach the limit, the inner wall of the rubber column comes into contact with the rigid guide core. At this time, the guide core bears part of the load and the equivalent stiffness increases rapidly, thereby limiting the large deformation of the column and avoiding excessive shearing, buckling or bond interface failure of the rubber column, thus ensuring the safety and reusability of the structure.

[0167] Furthermore, the guide hole on the upper section of the guide core and the guide hole corresponding to the rigid platform form a clearance guide fit, so that the upper end of the guide core maintains a preset axial clearance relative to the rigid platform in the axial direction, and does not contact the hole wall during the small displacement stage, thereby not forming a rigid force transmission path, so as to suppress the large deformation instability of the circumferential shear rubber column and improve the overall stability and repeatability of the structure.

[0168] Furthermore, the parameters of the rigid guide core are determined by the following formula:

[0169]

[0170]

[0171]

[0172]

[0173] In the formula, The height of the guide core, The cross-sectional area of ​​the guide core. This represents the shear displacement during normal operation. This represents the shear strain during normal operation. This represents the maximum permissible shear displacement during normal operation. This represents the maximum allowable shear strain during normal operation.

[0174] Furthermore, radial clearance The value is between 0.3mm and 0.5mm.

[0175] Furthermore, a countersunk hole is made in the center of the rigid base plate to provide a rigid connection for the rigid guide core.

[0176] Furthermore, the diameter of the lower countersunk hole can be determined by the following formula:

[0177]

[0178]

[0179]

[0180] In the formula, The diameter of the lower end retaining section of the guide core, Interference quantity The over-excess coefficient, The diameter of the countersunk hole.

[0181] Furthermore, the depth of the countersunk hole interference fit section It can be determined by the following formula:

[0182]

[0183]

[0184]

[0185] In the formula, The contact area between the lower end of the guide core retaining section and the countersunk hole. This is the maximum axial force that the guide core may withstand under abnormal conditions. The average shear stress on the interface of the interference fit section. This represents the allowable shear stress of the material.

[0186] Furthermore, a tenon section for guiding assembly is provided at the upper end of the guide core, and a corresponding guide hole is provided in the rigid platform. The axial depth of the guide hole is greater than the axial length of the upper tenon, thereby forming a preset axial gap between the upper end of the guide core and the rigid platform, so that the upper end of the guide core does not make a dead contact with the rigid platform in the axial direction.

[0187] Furthermore, the dimensions of the guide hole on the rigid platform are determined by the following formula:

[0188]

[0189] In the formula, For axial clearance, This refers to the depth of the guide hole.

[0190] Furthermore, the bending strength of the guide core under extreme conditions of acceleration exceeding 50g and instantaneous impact velocity exceeding 10m / s. It can be determined by the following formula:

[0191]

[0192]

[0193] In the formula, This represents the maximum shear force that the guide core may withstand under extreme working conditions. The yield strength of the material. This is for the safety factor.

[0194] Furthermore, a certain radial clearance needs to be allowed in the diameter of the upper guide hole. This allows the guide core body to pass smoothly, and its dimensions can be determined by the following formula:

[0195]

[0196] Furthermore, circumferential shear rubber columns are installed by bonding shallow grooves to a rigid base plate with structural adhesive. The load-bearing capacity of a single bonded surface is provided by the combined bond area of ​​the bottom surface and the bond area of ​​the sidewalls.

[0197] Furthermore, the bottom bonding area of ​​the bonding surface. for:

[0198]

[0199] Furthermore, the depth of a single slot is Sidewall bonding area for:

[0200]

[0201] Furthermore, the depth of a single slot can be determined by the following formula:

[0202]

[0203]

[0204]

[0205]

[0206]

[0207] In the formula, This represents the total bonding area. This represents the maximum force transmitted to the bonding interface from a single rubber column under extreme load. Minimum bonding area, This represents the allowable shear stress of the structural adhesive. This represents the minimum depth of the slot in a single shear rubber column.

[0208] Furthermore, a central vertical rubber column is installed by bonding a shallow groove to a structural adhesive on a rigid base plate. The load-bearing capacity of the bonding surface is provided by the bonding area of ​​the bottom surface and the bonding area of ​​the side wall.

[0209] Furthermore, the bottom bonding area of ​​the bonding surface. for:

[0210]

[0211] Furthermore, the depth of a single slot is Sidewall bonding area for:

[0212]

[0213] Furthermore, the depth of a single slot can be determined by the following formula:

[0214]

[0215]

[0216]

[0217]

[0218]

[0219] In the formula, The total bonding area between the central vertical rubber column and the rigid base plate. This represents the maximum force transmitted to the bonding interface from a single rubber column under extreme load. Minimum bonding area, This represents the allowable shear stress of the structural adhesive. The minimum depth of the slot in the central vertical rubber column.

[0220] Furthermore, the groove depth on the rigid platform is the same as the groove depth on the rigid base plate.

[0221] The dummy bionic structure achieves bionic simulation of the human head under multidimensional impact through the cooperation between its components, improving the bio-realism and ensuring the validity and accuracy of human injury test data.

[0222] Example

[0223] This embodiment provides a three-dimensional soft-connection structure for measuring the head acceleration of a hybrid third-generation dummy, such as... Figures 1 to 4 As shown, the structure includes a rigid base plate installed inside the dummy's head shell, a rigid platform above the base plate, a central vertical rubber column arranged between the base plate and the platform, four circumferential shear rubber columns, and rigid guide cores corresponding to the circumferential shear rubber columns. An accelerometer is fixedly installed on the rigid platform. The central vertical rubber column and the four circumferential shear rubber columns are symmetrically arranged around the center of gravity of the mass block, so that the central vertical rubber column mainly bears the vertical support and rebound, while the circumferential shear rubber columns mainly bear the shear displacement generated by horizontal impact and rotational motion, thereby achieving a three-dimensional flexible connection and energy dissipation between the head mass block and the skull.

[0224] The equivalent mass of the rigid platform and sensors is set to 0.1 kg. To ensure that the vertical natural frequency of the head-mounted flexible connection system is close to 25 Hz, this embodiment selects an overall vertical equivalent stiffness of approximately 2.0–3.0 × 10³ N / m based on a single-degree-of-freedom approximation. Considering the central vertical rubber column as the main vertical support component, this embodiment assigns 70%–90% of the overall vertical equivalent stiffness to the central vertical rubber column, with the remainder provided by the vertical compressive stiffness of the circumferential shear rubber column. This ensures compliance and stability in both horizontal and rotational directions while maintaining the target vertical frequency.

[0225] In terms of geometric dimensions, the rigid base plate in this embodiment is a cuboid structure with a length of 46mm, a width of 42mm, and a height of 10mm; the dimensions of the rigid platform are the same as those of the rigid base plate. The central vertical rubber column is a pure rubber column with a height of 15mm and a diameter of 11mm. Four circumferential shear rubber columns are evenly arranged around the central vertical rubber column, with a height of 15mm; each circumferential shear rubber column has a "one column, one core" structure, that is, a through inner hole is set at the axial center of the circumferential shear rubber column, and a rigid guide core is placed in the inner hole to maintain radial clearance. The outer diameter of the circumferential shear rubber column is... The inner diameter is 12mm. The structure has a diameter of 6.8 mm and is divided into three segments—first modulus, second modulus, and third modulus—from the inside out in the radial direction. The diameters of the radial segment boundaries are respectively... =8.8mm =10mm =12mm, that is, the thickness of the first layer is 1mm, the thickness of the second layer is 0.6mm, and the thickness of the outer layer is 1mm, so as to form a shear bearing capacity and limiting margin that are gradually enhanced from the inside to the outside.

[0226] Regarding material formulation, the central vertical rubber column uses room temperature vulcanizing silicone rubber, with a vertical equivalent elastic modulus of approximately 0.4 MPa, to provide vertical cushioning and rebound. The three radially layered circumferential shear rubber columns all use a silicone rubber system, with different shear moduli obtained by adjusting the filler and crosslinking agent ratios: the first shear modulus... Approximately 0.1 MPa, second shear modulus Approximately 0.2 MPa, third shear modulus The shear modulus is approximately 0.35 MPa, ensuring a monotonically increasing relationship from the inside out. ,in Approximately 2 times, Approximately 1.75 times that of the standard. The circumferential shear rubber column is integrally formed by layered casting: in the small shear deformation stage, the first modulus material deforms preferentially to reduce high-frequency impact, and in the stage of increased shear deformation, the second and third modulus materials gradually participate in the stress, so that the equivalent shear stiffness increases step by step, thereby obtaining a progressively hardened shear response and improving the stability in the large deformation stage.

[0227] The rigid guide core is configured as a single core per column: each circumferential shear rubber column is equipped with one rigid guide core. The guide core is integrally machined from 40Cr tempered steel, with a main body diameter of 6mm, corresponding to an inner diameter of 6.8mm for the circumferential shear rubber column, thus creating a radial gap between the guide core and the inner hole. The radial clearance is 0.4 mm. With this radial clearance, within the normal operating displacement range, the inner wall of the rubber column does not contact the guide core, thus avoiding the formation of a rigid force transmission path. When a strong impact or abnormal working conditions cause the shear displacement to increase to near the limit, the inner wall of the rubber column contacts the guide core, and the guide core bears part of the load and rapidly increases the equivalent stiffness, thereby limiting the large deformation of the rubber column, avoiding excessive shearing, instability, or interface damage, and improving structural safety and reusability.

[0228] Regarding the connection between the guide core and the base plate, the lower section mating hole and the lower end retaining section of the guide core are connected by an interference fit, with an interference coefficient of [value missing]. =0.001, then the diameter of the lower section fitting hole is determined by the formula. =5.994 mm; the mating section depth is 6 mm. The upper guide hole and the guide core body adopt a clearance guide fit. The diameter of the upper guide hole is 6.1 mm to form a guide clearance, and the depth of the upper guide hole is 1.5 mm to accommodate the rounded corner of the guide core shoulder and provide assembly guide space. At the same time, a corresponding guide hole is set in the rigid platform, and its axial depth is greater than the axial length of the upper guide section of the guide core, thereby forming a preset axial clearance between the upper end of the guide core and the rigid platform. =1mm, to avoid dead contact during small displacement stages.

[0229] Regarding the connection between the rubber columns and the base plate and platform, the central vertical rubber column and the circumferential shear rubber column achieve geometric locking with the rigid base plate and rigid platform through annular grooves, and are bonded together using structural adhesive. The bottom diameter of the groove is slightly larger than the outer diameter of the rubber column to allow for the thickness of the structural adhesive layer, and the groove depth... The groove depth is determined based on the shear strength requirements of the adhesive layer; considering the verification results of the maximum force transmission of a single column and the allowable shear stress of the adhesive layer, this embodiment adopts the groove depth. =3 mm, with symmetrically arranged groove structures at both ends to improve the bearing area and peel resistance of the bonding interface.

[0230] By selecting the aforementioned geometric dimensions and material parameters, this embodiment provides the main buffering and rebound in the vertical direction through a central vertical pure rubber column, and provides flexible connection in the horizontal and rotational directions through four circumferential shear rubber columns, forming a progressively hardened shear response through radial layered composite. At the same time, the one-column-one-core structure of the circumferential shear rubber columns, under the mechanism of "non-contact filtering under normal working conditions and contact limiting under abnormal large deformation," achieves the working mode of "flexible filtering under normal working conditions and stiffness surge limiting during large deformation stages," thereby improving the effectiveness and repeatability of head acceleration measurement under multi-dimensional impact conditions.

Claims

1. A dummy head bionic structure for multi-dimensional impact human body damage test, characterized in that, The headform inner shell (1), the rigid base plate (2), the central vertical rubber column (3), the circumferential shear rubber column (4), the rigid guide core (5), the rigid platform (6) and the head acceleration sensor (7) are included. The rigid base plate (2) is rigidly fixed with the inner wall of the headform inner shell (1); the head acceleration sensor (7) is installed on the rigid platform (6) with the height aligned with the center of the skull and brain; the central vertical rubber column (3) is arranged at the center between the rigid base plate (2) and the rigid platform (6) to provide vertical support stiffness; a plurality of circumferential shear rubber columns (4) are evenly arranged along the circumferential direction of the central vertical rubber column (3) to bear the shear displacement generated by horizontal impact and rotational motion; the cross section of the circumferential shear rubber column (4) is annular, the rigid guide core (5) is arranged in the circumferential shear rubber column (4) and a radial gap is provided between the circumferential shear rubber column (4) and the rigid guide core (5); the lower segment of the rigid guide core (5) is installed in interference fit with the rigid base plate (2) and the upper segment is installed in clearance fit with the rigid platform (6); the central vertical rubber column (3) and the circumferential shear rubber column (4) are connected with the rigid base plate (2) and the rigid platform (6) by structural adhesive.

2. The mannequin head bionical structure according to claim 1, characterized in that The lower end of the rigid guide core (5) is interference fitted with the counterbore on the rigid base plate (2) through a retaining segment, and the upper end of the rigid guide core (5) is clearance fitted with the guide hole of the rigid platform (6) through a guide segment; The rigid base plate (2) and the rigid platform (6) are provided with shallow grooves matched with the central vertical rubber column (3) and the circumferential shear rubber column (4), and the central vertical rubber column (3), the circumferential shear rubber column (4) and the matched shallow groove bottom and side wall are bonded.

3. The mannequin head bionical structure according to claim 2, characterized in that Column height of central vertical rubber column Is determined by the following equation: ， ， In the formula, Htargetis the target height of the acceleration block when it is in the center of the brain, Hrigidis the thickness of the rigid base plate, Hplatformis the thickness of the rigid platform; Equivalent vertical stiffness of central vertical rubber column Determined according to the following formula: ， wherein is the target natural frequency, is the equivalent mass, is the modulus of elasticity of the central vertical rubber column material, is the cross-sectional area of the central vertical rubber column; Central vertical rubber column cross-sectional dimension is obtained from the equation: ， 。 4. The mannequin head bionical structure according to claim 3, characterized in that The circumferential shear rubber column (4) has a radial layered composite structure, including a first modulus rubber layer, a second modulus transition layer and a third modulus rubber layer from inside to outside, and the shear stiffness of a single shear rubber column is determined by the following formula: ， ， wherein, G1 is the shear stiffness of the first modulus rubber layer, G2 is the shear stiffness of the second modulus transition layer, G3 is the shear stiffness of the third modulus rubber layer, G is the total shear stiffness of the one shear rubber column; The size of a single shear rubber column is determined by the following formula: ， ， ， ， ， ， wherein D is the inner diameter of the shear rubber column, D is the diameter of the rigid guide core, D is the radial gap between the rigid guide core and the shear rubber column, D is the outer diameter of the shear rubber column, Ae is the equivalent area of the first layer, Ee is the elastic modulus of the first layer, H is the height of the shear rubber column; The height-diameter ratio of a single shear rubber column and the minimum thickness size of each layer are determined by the following formula: ， ， In the formula, is the height-to-diameter ratio, is empirically valued at 4, is the first layer thickness.

5. The mannequin head bionical structure according to claim 4, characterized in that The size of the rigid guide core is determined by the following formula: ， ， ， wherein L is the length of the lower holding section, L is the length of the working section, L is the length of the upper guiding section, D is the diameter of the rigid guiding core, H is the height of the guiding core.

6. The mannequin head bionical structure of claim 5, wherein, The parameters of the rigid guide core are determined by the following formula: ， ， ， ， wherein is the cross-sectional area of the guide core, is the shear displacement at work, is the shear strain at work, is the maximum allowable shear displacement at work, is the maximum allowable shear strain at work.

7. The mannequin head bionical structure according to claim 6, characterized in that The size of the counterbore on the rigid base plate (2) matched with the rigid guide core (5) satisfies the following formula: ， ， ， wherein D is the diameter of the lower end holding section of the guide core, is the interference amount, is the interference coefficient, is the hole diameter of the counterbore; Depth of counterbore interference fit section Is determined by the equation: ， ， ， wherein is the contact area between the lower end holding section of the guide core and the counterbore, is the maximum axial force that the guide core can withstand, is the average shear stress on the interface of the interference fit section, is the material allowable shear stress.

8. The mannequin head bionical structure according to claim 7, characterized in that The size of the guide hole on the rigid platform is determined by the following formula: ， wherein is the axial gap, is the guide hole depth; Bending strength of the guide core under extreme working conditions with acceleration exceeding 50 g and instantaneous impact speed exceeding 10 m / s Is determined by the following equation: ， ， wherein is the maximum shear force that the guide core can withstand under extreme working conditions, is the yield strength of the material, is the safety factor; Diameter of guide hole Determined according to the following formula: ， In the formula, is the radial clearance of the guide hole and the rigid guide core guide section.

9. The mannequin head bionical structure according to claim 8, characterized in that Single circumferential shear rubber column (4) and shallow groove adhesive surface bottom adhesive area Is: ， The single slot hole depth is The side wall bonding area of is: ， The single slot hole depth is determined by the following formula: ， ， ， ， ， wherein A is the total bonding area, F is the maximum force transmitted to the bonding interface by a single rubber column under extreme load, Amin is the minimum bonding area, T is the allowable shear stress of the structural adhesive, Dmin is the minimum depth of a single slot.

10. A method of designing a mannequin head bionic structure according to any one of claims 1-9, characterized in that, The method comprises the following steps: S1: Establish a single degree of freedom equivalent model of "skull-soft connection-acceleration block", and determine the equivalent mass , target natural frequency and damping ratio ; S2: determining the equivalent stiffness of the soft connection from the target natural frequency and damping ratio and equivalent damping ; S3: determining the equivalent vertical stiffness of the central vertical rubber column according to the equivalent stiffness and cross-sectional dimensions; S4: Determine the total shear stiffness of the circumferential shear rubber column according to the horizontal shear demand and the effective area of each layer of the single shear rubber column and the outer diameter S5: Determine the diameter, length of the rigid guide core and the radial clearance to the shear rubber column ; S6: checking the shear strength and bending strength of the guide core under extreme conditions of more than 50g acceleration and instantaneous impact speed of more than 10m / s; S7: designing the interference fit hole diameter and interference fit segment depth of the rigid base plate counterbore; S8: determining the slot hole depth according to the bonding load check.

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