Guardrail structure optimization method based on collision damage degree simulation prediction
By using a guardrail structure optimization method based on collision damage simulation prediction, the problems of long design cycle, lack of damage prediction, and delayed maintenance of highway guardrails have been solved. This method achieves high-precision damage prediction and low-cost guardrail optimization design, thereby improving maintenance efficiency.
Patent Information
- Application Number
- CN202511100920.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-07
- Publication Date
- 2025-11-21
AI Technical Summary
Existing highway guardrails suffer from long design cycles, lack of damage prediction, and delayed maintenance. Current technologies cannot effectively quantify damage evolution and are costly.
A guardrail structure optimization method based on collision damage degree simulation prediction is adopted. Through parametric geometric modeling, material constitutive model construction, multi-condition collision simulation and damage quantification assessment, combined with explicit dynamic analysis and optimization algorithm, the guardrail geometry is optimized to meet safety performance requirements.
It improves the accuracy of guardrail damage prediction, reduces design and maintenance costs, reduces the number of real vehicle tests, improves maintenance efficiency, and ensures the safety performance of guardrails under multiple working conditions.
Smart Images
Figure CN120995855A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of highway guardrail structure optimization technology, and in particular to a guardrail structure optimization method based on collision damage degree simulation prediction. Background Technology
[0002] As a core anti-collision facility on highways, the safety of guardrails directly affects the fatality rate in highway traffic accidents. Statistics show that approximately 35% of major accidents involve collisions with the median strip, with openings in the guardrails, due to structural discontinuities, becoming a focal point of risk. While existing SAm-grade guardrails have passed real-vehicle testing (JTG B05-01—2013), they still have the following shortcomings:
[0003] 1. Long design cycle: The cost of a single test exceeds 2 million yuan (such as the HBSV series test report), and it takes 3-6 months;
[0004] 2. Lack of damage prediction: The test only provides a pass / fail conclusion (such as the "Evaluation Indicators" on page 14 of the report), and cannot quantify the damage evolution;
[0005] 3. Delayed maintenance: Residual deformation of guardrails (such as in report P15: 0.14m residual deformation after a large passenger bus collision) requires manual inspection to detect, resulting in delays in repair.
[0006] To address the aforementioned shortcomings, those skilled in the art have explored the following three technical approaches:
[0007] Empirical formula method: based on collision energy E k The deformation is estimated, but material nonlinearity (such as the yield characteristics of Q235 steel under high-speed impact) is ignored, and the prediction error exceeds 30%.
[0008] Simplified simulation method: The guardrail is simplified using beam elements (ignoring the details of the connectors), which cannot reproduce the "damage at the connection" situation in the report;
[0009] Big data early warning: Deploying sensors to monitor deformation, but implementation costs are high, it is easily affected by external environmental factors, and damage cannot be predicted.
[0010] Therefore, those skilled in the art need a guardrail structure optimization method that can establish a quantitative mapping relationship between collision parameters (velocity / mass / angle) and guardrail damage. Summary of the Invention
[0011] The purpose of this invention is to solve the above problems by designing a guardrail structure optimization method based on collision damage degree simulation prediction.
[0012] The technical solution of the present invention to achieve the above objectives is a guardrail structure optimization method based on collision damage degree simulation prediction, which includes the following steps:
[0013] Step 1: Parametric geometric modeling:
[0014] Based on the design drawings of the guardrail (such as the drawings in the appendix), extract the geometric dimensions of the guardrail (such as the height, thickness, slope of the impact surface, size of the climbing ledge, and length of a single section), and use parametric modeling software (such as CATIA or SolidWorks) to build a three-dimensional geometric model. Parameterizing the geometric dimensions means that these dimensions can be used as variables, and after obtaining the simulation prediction results, the geometric dimensions can be flexibly adjusted according to the simulation prediction results.
[0015] Step 2: Construction of the material constitutive model:
[0016] A material constitutive model (i.e., the Johnson-Cook model) is constructed, and the strain rate term is calculated. The model parameters of the material constitutive model are determined based on the experimental data of the materials used in the guardrail (including but not limited to concrete and connectors). These parameters include, but are not limited to, yield strength, hardening modulus, strain rate sensitivity coefficient, etc.
[0017] Step 3: Multi-condition collision simulation:
[0018] The simulation conditions are set, including but not limited to: vehicle type (small passenger car, large passenger car, large truck), collision speed, collision angle, etc. The simulation process of different conditions is solved based on the explicit dynamic analysis method (i.e., LS-DYNA), and the transient response data (such as the deformation cloud map and dynamic response of the guardrail) are calculated during the collision process.
[0019] Step 4: Quantitative assessment of damage:
[0020] The transient response data output from step 3 is input into the damage model to quantitatively evaluate the dynamic camber value of the vehicle, thereby determining the state of the vehicle after a collision. This provides a basis for the simulation prediction of guardrail damage and also provides a basis for dynamically optimizing the geometric dimensions of the guardrail.
[0021] Step 5: Security performance optimization feedback:
[0022] The maximum lateral dynamic deformation of the guardrail (D) max ) and the vehicle's dynamic camber value as constraints (such as D) max And VI does not exceed the standard limit, i.e., D max (≤0.35m or VI≤1.45m), use optimization algorithms to find the optimal solution for the geometric dimensions of the guardrail.
[0023] Step 6: Perform performance analysis on the optimized guardrail.
[0024] Using simulated collisions, the blocking, buffering, and guiding functions of the optimized guardrail are quantitatively analyzed. The geometric dimensions of the guardrail are determined based on the quantitative analysis results. If all quantitative analysis results are qualified, the quantitative analysis results are output. If at least one quantitative analysis result is unqualified, the process returns to step 5 to make a second adjustment to the geometric dimensions of the optimized guardrail and ensure that the blocking, buffering, and guiding functions of the optimized guardrail all meet the qualified standards.
[0025] The expression for the material constitutive model (i.e., the Johnson-Cook model) in step 2 is as follows:
[0026]
[0027] In the formula, σ1 is the rheological stress, and ε is the equivalent plastic strain. To standardize the strain rate, T * Here, A is the normalized temperature, B is the yield strength, n is the hardening modulus, C is the strain rate sensitivity coefficient, and m is the concrete fitting parameter. The parameters A, B, n, C, and m are all derived from experimental measurements of the material.
[0028] The transient response data output by the explicit dynamic analysis method (LS-DYNA) in step 3 includes: the acceleration of the equation of motion and the maximum lateral dynamic deformation of the guardrail (calculated from the vehicle's contact force and strain rate terms).
[0029] The equation of motion is:
[0030]
[0031] In the formula, M is the mass matrix (generated from vehicle / guardrail density), C n Let F be the damping matrix (Rayleigh damping coefficient α = 150, β = 0.1), K be the nonlinear stiffness matrix (updated with material plastic deformation), and F be the damping matrix. ext This is the collision force vector;
[0032] The main function of the equations of motion is to solve for the nodal accelerations ü and to iterate the displacements using the central difference method. in,
[0033] The contact force between the guardrail and the vehicle is represented by the penalty function method, and its expression is:
[0034]
[0035] In the formula, F c Where is the contact force, k is the contact stiffness (taken as 10% of the concrete stiffness, k = 2 × 10⁴ N / mm), and δ is the penetration depth (limited to δ ≤ 0.1 mm). The penetration velocity is obtained by differentiating δ.
[0036] Maximum lateral dynamic deformation D of the guardrail max for:
[0037]
[0038] The strain rate term is obtained from the material constitutive model.
[0039] The expression for the damage model in step 4 is:
[0040] D max =α·E k +β·VI
[0041] In the formula, D max E represents the maximum lateral dynamic deformation of the guardrail (m). k E represents the collision kinetic energy (kJ). k =1 / 2mv 2 It is calculated from the equation of motion, where VI is the vehicle dynamic camber value (m), and α / β are the correlation coefficients of the material / structure (calibrated by experiments), where α is the energy absorption coefficient (calibrated value 0.0008) and β is the structural geometric influence coefficient (calibrated value 0.12).
[0042] The optimization algorithms in step 5 include, but are not limited to, response surface methodology or genetic algorithm.
[0043] The process of quantitatively analyzing and optimizing the blocking function of the guardrail in step 6 is as follows:
[0044] Simulation Analysis: Extracting the maximum lateral displacement (D) of the vehicle in the simulation. vehicle ) and the maximum dynamic deformation of the guardrail (D) max ), calculate the blocking efficiency:
[0045]
[0046] If η block ≥90% and D vehicle If the depth is ≤0.5m (standard limit), the barrier function is deemed qualified.
[0047] In the formula, D vehicle D represents the lateral displacement of the vehicle's center of gravity (m). max η is the maximum lateral dynamic deformation of the guardrail (m). block For blocking efficiency (%).
[0048] The process of quantitatively analyzing and optimizing the buffer function of the guardrail in step 6 includes:
[0049] Calculate the average deceleration based on the vehicle acceleration time history curve (a(t)). and peak acceleration (a max ):
[0050]
[0051] In the formula, T is the collision duration, which must satisfy... And a max ≤40g (g is the acceleration due to gravity), a(t): vehicle acceleration time history (m / s²) 2 ), The average deceleration (m / s²) 2 );
[0052] Calculate the energy absorption rate of the guardrail:
[0053] E absorbed =∫F c ·δdt
[0054] In the formula, F c Let E be the contact force, δ be the deformation of the guardrail, and E be the contact force. absorbed The guardrail absorbs energy (kJ), and when the energy absorption rate exceeds the total collision kinetic energy (E) k When the buffer reaches 70%, the buffer function is considered qualified.
[0055] The process of quantitatively analyzing and optimizing the guiding function of the guardrail in step 6 is as follows:
[0056] Calculate the angle (θ) between the vehicle's direction of motion after the collision and the guardrail axis:
[0057]
[0058] In the formula, v x and v y These are the longitudinal and lateral velocity components of the vehicle (m / s), respectively. If θ ≤ 15°, the guidance function is qualified. θ is the vehicle yaw angle (°).
[0059] Compared with the prior art, the present invention has the following beneficial effects:
[0060] 1. This invention effectively improves the accuracy of collision damage prediction for guardrails by establishing a correlation between dynamic deformation and energy, and can improve the prediction accuracy to 95%, providing a solid foundation for subsequent guardrail structure optimization.
[0061] 2. This invention utilizes multi-condition simulation to replace real vehicle testing, effectively reproducing the full scenarios of HBSV-1901 / 1902 / 1903, avoiding repetitive real vehicle testing, and reducing the experimental cost and difficulty of guardrail structure optimization design;
[0062] 3. This invention utilizes a safety performance optimization feedback method to trigger the guardrail maintenance mechanism by predicting the degree of guardrail deformation, which greatly reduces the workload of maintenance personnel and effectively improves maintenance efficiency. Attached Figure Description
[0063] Figure 1 This is a flowchart of a guardrail structure optimization method based on collision damage degree simulation prediction as described in this invention;
[0064] Figure 2 This is a simulation diagram of the collision between the small passenger car and the guardrail described in this invention;
[0065] Figure 3 This is a simulation diagram of the collision between the large passenger bus and the guardrail described in this invention;
[0066] Figure 4 This is a simulation diagram of the collision between the large truck and the guardrail described in this invention;
[0067] Figure 5 This is the collision result analysis table of Embodiment 1 of the present invention;
[0068] Figure 6 This is the collision result analysis table of Embodiment 2 of the present invention;
[0069] Figure 7 This is a side view of the guardrail before the optimization of this invention;
[0070] Figure 8 This is the optimized side view drawing of the guardrail according to the present invention;
[0071] Figure 9 This is a comparative analysis table of the guardrail before and after optimization in Embodiment 1 of the present invention;
[0072] Figure 10 This is a comparative analysis table of the guardrail before and after optimization in Embodiment 2 of the present invention. Detailed Implementation
[0073] The present invention will now be described in detail with reference to the accompanying drawings, such as... Figure 1-4 As shown;
[0074] A method for optimizing guardrail structures based on collision damage simulation prediction, comprising the following steps:
[0075] Step 1: Parametric geometric modeling:
[0076] Step 1 mainly addresses the technical problems of traditional modeling methods being inefficient, unable to adapt to changes in the guardrail structure (such as size adjustments), and unable to meet the needs of simulation prediction.
[0077] Based on the design drawings of the guardrail (such as...) Figure 7Extract the geometric dimensions of the guardrail from the drawings, and use parametric modeling software (such as CATIA or SolidWorks) to create a three-dimensional geometric model of the guardrail. Parameterizing the geometric dimensions means that these dimensions can be used as variables, and the geometric dimensions can be flexibly adjusted based on the simulation prediction results.
[0078] Step 1 can quickly generate guardrail models of different specifications, providing a basis for analysis and calculation for subsequent simulation prediction.
[0079] Step 2: Construction of the material constitutive model:
[0080] Step 2 is mainly to address the nonlinear behavior of materials during the collision process (such as plastic deformation, strain rate effect, etc.) and effectively ensure the accuracy of the simulation process.
[0081] A material constitutive model (i.e., the Johnson-Cook model) is constructed, and the strain rate term is calculated. The model parameters of the material constitutive model are determined based on the experimental data of the materials used in the guardrail (including but not limited to: concrete, connectors, etc.). These parameters include, but are not limited to: yield strength, hardening modulus, strain rate sensitivity coefficient, etc.
[0082] Step 2 can accurately simulate the deformation and failure behavior of materials under high-speed collisions.
[0083] Step 3: Multi-condition collision simulation:
[0084] Step 3 is mainly to address the technical challenges of diverse actual collision scenarios (such as different vehicle models, speeds, and angles). The collision simulation process needs to cover a variety of collision conditions.
[0085] The simulation conditions are set, including but not limited to: vehicle type (small passenger car, large passenger car, large truck), collision speed, collision angle, etc. The simulation process of different conditions is solved based on the explicit dynamic analysis method (i.e., LS-DYNA), and the transient response data (such as the deformation cloud map and dynamic response of the guardrail) are calculated during the collision process.
[0086] Step 3 can simulate a real collision test and output transient response data such as guardrail deformation and vehicle trajectory.
[0087] Step 4: Quantitative assessment of damage:
[0088] Step 4 mainly addresses the technical challenges of extracting key indicators from simulation data and establishing a damage prediction model.
[0089] The transient response data output from step 3 is input into the damage model to quantitatively evaluate the dynamic camber value of the vehicle, thereby determining the state of the vehicle after a collision. This provides a basis for the simulation prediction of guardrail damage and also provides a basis for dynamically optimizing the geometric dimensions of the guardrail.
[0090] Step 5: Security performance optimization feedback:
[0091] Step 5 primarily addresses how to improve the guardrail design to reduce weight or cost while meeting safety standards (such as SAM level).
[0092] The maximum lateral dynamic deformation of the guardrail (D) max ) and the vehicle's dynamic camber value as constraints (such as D) max And VI does not exceed the standard limit, i.e., D max (≤0.35m or VI≤1.45m), use optimization algorithms to find the optimal solution for the geometric dimensions of the guardrail.
[0093] Step 5 can optimize the guardrail structure while ensuring safety performance, thereby achieving a lightweight effect or cost reduction effect for the guardrail.
[0094] The geometric parameters in step 1 include: the height of the guardrail (preferably 1.00m), the thickness of the guardrail, the slope of the impact surface of the guardrail, the size of the climbing barrier of the guardrail, and the length of a single section of the guardrail (1.72m).
[0095] The expression for the material constitutive model (i.e., the Johnson-Cook model) in step 2 is as follows:
[0096]
[0097] In the formula, σ1 is the rheological stress, and ε is the equivalent plastic strain. To standardize the strain rate, T * Here, A is the normalized temperature, B is the yield strength, n is the hardening modulus, C is the strain rate sensitivity coefficient, and m is the fitting parameter for concrete. Parameters A, B, n, C, and m are all derived from experimental measurements of the material.
[0098] The transient response data output by the explicit dynamic analysis method (LS-DYNA) in step 3 includes: the acceleration of the equation of motion and the maximum lateral dynamic deformation of the guardrail (calculated from the vehicle's contact force and strain rate terms).
[0099] The equation of motion is:
[0100]
[0101] In the formula, M is the mass matrix (generated from vehicle / guardrail density), C nLet F be the damping matrix (Rayleigh damping coefficient α = 150, β = 0.1), K be the nonlinear stiffness matrix (updated with material plastic deformation), and F be the damping matrix. ext This is the collision force vector;
[0102] The main function of the equations of motion is to solve for the nodal accelerations ü and to iterate the displacements using the central difference method. in, Δt is the duration of acceleration;
[0103] The contact force between the guardrail and the vehicle is represented by the penalty function method, and its expression is:
[0104]
[0105] In the formula, F c Where is the contact force, k is the contact stiffness (taken as 10% of the concrete stiffness, k = 2 × 10⁴ N / mm), and δ is the penetration depth (limited to δ ≤ 0.1 mm). The penetration velocity is obtained by differentiating δ.
[0106] Maximum lateral dynamic deformation D of the guardrail max for:
[0107]
[0108] Among them, the strain rate term is The strain rate term is obtained from the material constitutive model. The expression for the damage rate model in step 4 is:
[0109] D max =α·E k +β·VI
[0110] In the formula, D max E represents the maximum lateral dynamic deformation of the guardrail (m). k E represents the collision kinetic energy (kJ). k =1 / 2mv 2 It is calculated from the equation of motion, where VI is the vehicle dynamic camber value (m), and α / β are the correlation coefficients of materials / structures (calibrated by experiments), where α is the energy absorption coefficient (calibrated value 0.0008) and β is the structural geometric influence coefficient (calibrated value 0.12).
[0111] The optimization algorithms in step 5 include, but are not limited to, response surface methodology or genetic algorithm.
[0112] The process of finding the optimal geometric dimensions using a genetic algorithm in step 5 is as follows:
[0113] First, let the variable x = [L, t], where L is the guardrail spacing (m) and t is the guardrail thickness (mm). The objective function f(x) = total guardrail mass (kg) needs to be minimized.
[0114] The constraints are:
[0115] g1(x)=D max (x)-0.35≤0 (maximum dynamic deformation constraint).
[0116] g2(x)=VI(x)-1.45≤0 (vehicle dynamic camber constraint);
[0117] Variable range:
[0118] Guardrail spacing L: [1.5, 2.0] mm,
[0119] Guardrail thickness t: [20, 50] cm;
[0120] Secondly, the optimization process of the genetic algorithm is as follows:
[0121] a. Establish the initial population:
[0122] Randomly generate N individuals (i.e., design variable combinations x) i =[L i ,t i To form an initial population, for example, N = 50, each individual randomly takes a value within a range;
[0123] b. Fitness assessment:
[0124] For each individual x i Call the model from steps 1-4 to calculate:
[0125] Step 1: Based on x i Construct a parametric model of the guardrail;
[0126] Step 2: The material model remains unchanged (concrete);
[0127] Step 3: Perform LS-DYNA simulation under standard operating conditions (such as a large truck collision) to obtain D. max (x i ) and VI(x i );
[0128] Step 4: Obtain D using the damage model (optional, or directly use simulation results). max And VI.
[0129] Calculate fitness (using penalty function method since it is constrained optimization):
[0130] fitness(x i )=f(xi )+penalty
[0131] Wherein, the penalty function is penalty = P1*max(0, g1(x) i ))+P2*max(0,g2(x i ))
[0132] Here, P1 and P2 are penalty factors (e.g., taking a large positive number like 10000), and violations of the constraints will result in penalties.
[0133] c. Select operation:
[0134] Using roulette wheel selection or tournament selection, individuals with lower fitness (lighter mass and meeting constraints) have a higher probability of being selected.
[0135] d. Crossover operation:
[0136] Cross over the selected individuals (e.g., simulate binary crossover SBX) to produce offspring; for example, two parent individuals x1 = [L1,t1] and x2 = [L2,t2] will produce two offspring after crossover.
[0137] e. Mutation operation:
[0138] To maintain population diversity, offspring can be mutated (e.g., by Gaussian mutation).
[0139] f. New generation population:
[0140] The parent and offspring generations are merged, and N individuals with high fitness are selected to form a new generation of population;
[0141] g. Termination condition:
[0142] Repeat the bf step until the maximum number of iterations (e.g., 100 generations) is reached or the fitness converges;
[0143] It is important to note that the key mathematical expressions in the optimization process include:
[0144] a. Objective function:
[0145] f(x) = Total mass of guardrail = Mass of concrete + Mass of connectors;
[0146] in:
[0147] Concrete mass = (Total length / L) * Mass of a single guardrail
[0148] Connector mass = (total length / L) * mass of a single connector;
[0149] b. Fitness of the penalty function method:
[0150] fitness(x) = f(x) + P1*max(0,D) max (x)-0.35)+P2*max(0,
[0151] VI(x)-1.45)
[0152] Furthermore, since evaluating each individual requires running LS-DYNA simulations (which are computationally intensive), cluster parallel computing can be used (e.g., evaluating 10 individuals simultaneously). Moreover, to accelerate optimization, a surrogate model (such as a Kriging model) can be established to replace the simulation in step 3. The surrogate model is trained using the initial samples and predicts D. max (x) and VI(x).
[0153] Finally, the optimization results are as follows:
[0154] The final output is the optimal solution x. * =[L * ,t * ], for example: L * =1.85mm,t * =36cm
[0155] At this point, the weight of the guardrail is reduced by 15% compared to the original design (L = 1.72 mm, t = 15 cm), and the following conditions are met:
[0156] D max (x * =0.33m≤0.35m
[0157] VI(x * =1.40m≤1.45m
[0158] Implementing a global search using a genetic algorithm avoids getting trapped in local optima and ensures that a lightweight solution is found in complex nonlinear problems; step 4 involves a damage model (D... max =α·E k +β·VI) is used for rapid evaluation, reducing the number of simulations; through the above process, the automatic optimization of guardrail design is achieved, significantly reducing R&D costs.
[0159] Step 6: Perform performance analysis on the optimized guardrail.
[0160] Using simulated collisions, the blocking, buffering, and guiding functions of the optimized guardrail are quantitatively analyzed. The geometric dimensions of the guardrail are determined based on the quantitative analysis results. If all quantitative analysis results are qualified, the quantitative analysis structure is output. If at least one quantitative analysis result is unqualified, the process returns to step 5 to make a second adjustment to the geometric dimensions of the optimized guardrail and ensure that the blocking, buffering, and guiding functions of the optimized guardrail all meet the qualified standards.
[0161] in,
[0162] The process of quantitatively analyzing and optimizing the barrier's blocking function is as follows:
[0163] Simulation Analysis: Extracting the maximum lateral displacement (D) of the vehicle in the simulation. vehicle ) and the maximum dynamic deformation of the guardrail (D) max ), calculate the blocking efficiency:
[0164]
[0165] If η block ≥90% and D vehicle If the distance is ≤0.5m (standard limit), the blocking function is deemed qualified.
[0166] Real vehicle analysis: A crash test was conducted using a standard test vehicle (such as a large bus with a mass of 14,000 kg and a speed of v = 80 km / h) to measure the relative distance between the vehicle's final stopping position and the guardrail.
[0167] In the formula, D vehicle D represents the lateral displacement of the vehicle's center of gravity (m). max η is the maximum lateral dynamic deformation of the guardrail (m). block For blocking efficiency (%);
[0168] Quantitative analysis and optimization of the guardrail's blocking function can effectively verify whether the guardrail can effectively prevent vehicles from crossing the median strip.
[0169] The process of quantitatively analyzing and optimizing the buffer function of the guardrail includes:
[0170] Calculate the average deceleration based on the vehicle acceleration time history curve (a(t)). and peak acceleration (a max ):
[0171]
[0172] In the formula, T is the collision duration, which must satisfy... And a max ≤40g (g is the acceleration due to gravity), a(t): vehicle acceleration time history (m / s²) 2 ), The average deceleration (m / s²) 2 );
[0173] Calculate the energy absorption rate of the guardrail:
[0174] E absorbed =∫F c ·δdt
[0175] In the formula, F cLet δ be the contact force, δ be the deformation of the guardrail, and the energy absorption rate need to reach the total collision kinetic energy (E). k Only when the buffering function is above 70% can it be considered qualified. absorbed It absorbs energy (kJ) for the guardrail.
[0176] The main purpose of quantitative analysis to optimize the buffering function of the guardrail is to assess the guardrail's ability to absorb collision energy and reduce vehicle acceleration to protect occupant safety.
[0177] The process of quantitatively analyzing and optimizing the guide function of the guardrail is as follows:
[0178] Calculate the angle (θ) between the vehicle's direction of motion after the collision and the guardrail axis:
[0179]
[0180] In the formula, v x and v y These are the longitudinal and lateral velocity components of the vehicle (m / s), respectively. If θ ≤ 15°, the guidance function is qualified. θ is the vehicle yaw angle (°).
[0181] The main purpose of the optimized guardrail guidance function after quantitative analysis is to ensure that vehicles slide along the guardrail after a collision, avoiding rollover or secondary collision.
[0182] Example 1;
[0183] The collision results are as follows Figure 5 As shown in the figure, the comparative analysis results of the guardrail before and after optimization are as follows: Figure 9 As shown;
[0184] The simulation results of a small passenger car collision were used, with a 1.5t small passenger car colliding with a guardrail.
[0185] During the collision, the vehicle did not cross, climb over, or straddle the guardrail. The guardrail components and their detachment parts did not intrude into the vehicle's passenger compartment, and their blocking function was in good condition.
[0186] The maximum lateral dynamic deformation (D) of the guardrail is 0.29 mm, and the maximum lateral dynamic displacement extension (W) of a single side guardrail is 353.29 mm. There is no obvious damage to the guardrail.
[0187] The collision occurred at 0.14 s. The maximum longitudinal and lateral components of the occupant's collision velocity were 3.84 m / s² and 7.28 m / s², respectively, both less than 12 m / s². The maximum longitudinal and lateral components of the occupant's post-collision acceleration were 83.4 m / s². 2 and 157.3 m / s 2 All are less than 200 m / s 2 The guardrail has a good buffer function.
[0188] It should be noted that the predicted damage to the guardrail under a collision with a small passenger vehicle (collision conditions: passenger vehicle weight 1.5t, speed 100km / h, collision angle 20°) is as follows:
[0189] Damage model output:
[0190] Maximum lateral dynamic deformation of the guardrail: D max =0.29mm
[0191] Vehicle dynamic camber value: VI = N / A (not applicable to small cars)
[0192] Damage prediction: The peak strain of the guardrail was 29.98 MPa (lower than the compressive strength of concrete). Neither the guardrail nor the connectors failed, and there was no structural damage.
[0193] Blocking function: qualified.
[0194] Buffering function: Peak longitudinal acceleration of occupants is 83.4 m / s². 2 Horizontal 157.3m / s 2 (all <200m / s) 2 ),qualified.
[0195] Guiding function: Vehicle yaw angle θ = arctan(v) y / v x )≤15°, qualified.
[0196] The simulation results of a 14t bus colliding with a guardrail were used to study the collision of a large passenger bus.
[0197] During the collision, the vehicle did not cross, climb over, or straddle the guardrail. The guardrail components and their detachment parts did not intrude into the vehicle's passenger compartment, and their blocking function was in good condition.
[0198] The maximum lateral dynamic deformation (D) of the guardrail is 27.7 mm, the maximum lateral dynamic displacement extension (W) of the guardrail is 377.7 mm, the maximum dynamic tilt (VI) of the vehicle is 868.95 mm, and the equivalent value of the maximum dynamic tilt (VI) of the vehicle is... n The value is 1216.53 mm.
[0199] The vehicle was successfully guided out of the collision, maintaining a normal driving posture without overturning, turning sideways, or making a U-turn. Furthermore, the wheel tracks left after the vehicle left the departure point met the requirements for guiding the vehicle out of the guide frame, indicating that the guiding function was in good condition.
[0200] It should be noted that the damage prediction results for the guardrail under a collision with a large passenger bus (collision conditions: bus weight 14t, speed 80km / h, collision angle 20°) are as follows:
[0201] Damage model output:
[0202] Maximum lateral dynamic deformation of the guardrail: D max =27.7mm
[0203] Vehicle dynamic camber value: VI = 868.95mm
[0204] Damage prediction: Peak concrete stress 70.74 MPa, local unit failure of the guardrail, axial force of the concrete guardrail not exceeded the limit (< yield strength 335 MPa).
[0205] Barrier function: The vehicle did not pass through / overturn, and the guardrail components did not intrude into the passenger compartment.
[0206] Guidance function: The vehicle trajectory meets the requirements for leaving the frame and there is no rollover.
[0207] The simulation results of a 25-ton truck colliding with a guardrail were used to illustrate the collision of a large truck.
[0208] During the collision, the vehicle did not cross, climb over, or straddle the guardrail. The guardrail components and their detachment parts did not intrude into the vehicle's passenger compartment, and their blocking function was in good condition.
[0209] The maximum lateral dynamic deformation (D) of the guardrail is 29.6 mm, the maximum lateral dynamic displacement extension (W) of the guardrail is 379.6 mm, the maximum dynamic tilt (VI) of the vehicle is 801.27 mm, and the equivalent value of the maximum dynamic tilt (VI) of the vehicle is... n The value is 1121.78 mm.
[0210] The vehicle was successfully guided out of the collision, maintaining a normal driving posture without overturning, turning sideways, or making a U-turn. Furthermore, the wheel tracks left after the vehicle left the departure point met the requirements for guiding the vehicle out of the guide frame, indicating that the guiding function was in good condition.
[0211] It should be noted that the damage prediction results for the guardrail under a collision with a large truck (collision conditions: bus weight 25t, speed 60km / h, collision angle 20°) are as follows:
[0212] Damage model output:
[0213] Maximum lateral dynamic deformation of the guardrail: D max =29.6mm
[0214] Vehicle dynamic camber value: VI = 801.27mm
[0215] Damage prediction: Peak concrete stress 80.79 MPa, connector stress 34.70 MPa (close to the guardrail yield limit).
[0216] Predicted risk: The stress of the connector (i.e., the connecting bolt) is critical, and there is a risk of connection failure.
[0217] Example 2;
[0218] The collision results are as follows Figure 6 As shown in the figure, the comparative analysis results of the guardrail before and after optimization are as follows: Figure 10 As shown;
[0219] The simulation results of a small passenger vehicle collision were used, with a 1.5t small passenger vehicle colliding with the guardrail.
[0220] During the collision, the vehicle did not cross, climb over, or straddle the guardrail. Guardrail components and their detachment parts did not intrude into the vehicle's passenger compartment, and their blocking function was effective. A passenger car colliding with a guardrail involves the following process: vehicle entry, frontal impact, vehicle steering, vehicle skidding, frontal landing, and departure from the guardrail.
[0221] Vehicle Entry: The passenger car approaches the guardrail at a 20° angle and a speed of 100 km / h at one-third of its length; Frontal Collision: The right front headlight and bumper of the passenger car are crushed and deformed, and the right front wheel climbs up the bottom slope of the guardrail; Vehicle Steering: Due to the angle between the vehicle's direction of travel and the guardrail, the right front of the vehicle deforms and absorbs energy, and the vehicle's direction of travel is adjusted to be along the guardrail; Vehicle Sliding: Due to the vehicle's inertia, the rear of the vehicle collides with the guardrail after steering, during which the vehicle climbs up the guardrail to its highest position; Front Landing: Because the impact surface with the guardrail is sloped, the vehicle fishtails, causing the rear of the vehicle to lift up, and the front of the vehicle contacts the road surface before the rear; Departure from Guardrail: The vehicle finally leaves the guardrail at a certain angle.
[0222] Because some units of the guardrail wall were damaged, the displacement value of the unit node in the collision area was the largest, reaching 40.08mm. In actual calculations, the maximum displacement of the guardrail is generally located at the top of the guardrail. By retrieving the displacement trajectory of the top node of the guardrail, the maximum lateral dynamic deformation value (D) of the guardrail can be extracted as 0.26mm, and the maximum lateral dynamic displacement extension value (W) of the guardrail on one side is 353.26mm. The guardrail has no obvious damage, the reinforcing steel is not exposed, and the reinforcing steel is not damaged.
[0223] The collision occurred at 0.18 s. The maximum longitudinal and lateral components of the occupant's collision velocity were 4.33 m / s² and 7.56 m / s², respectively, both less than 12 m / s². The maximum longitudinal and lateral components of the occupant's post-collision acceleration were 87.4 m / s². 2 and 131.5 m / s 2 All are less than 200 m / s 2 The guardrail has a good buffer function.
[0224] The vehicle successfully exited the collision area, maintaining a normal driving posture without rollover, lateral turn, or U-turn. Furthermore, the wheel tracks after leaving the departure point met the requirements for the guide exit frame, indicating good guiding function. A significant area of damage was observed on the front right side of the vehicle, with noticeable deformation of the right front headlight, right front wheel, and bumper.
[0225] It should be noted that the predicted damage to the guardrail under a collision with a small passenger vehicle (collision conditions: passenger vehicle weight 1.5t, speed 100km / h, collision angle 20°) is as follows:
[0226] D max =0.26mm (decrease of 10.3%), VI = N / A;
[0227] The maximum tensile force of the guardrail is 27.6 kN (far below the yield limit), and the peak stress drops to 16.64 MPa.
[0228] Advantages: Improved cushioning (occupant lateral acceleration 131.5 m / s²) 2 → A decrease of 16.4% compared to before optimization).
[0229] The simulation results of a 14-ton bus colliding with a guardrail were used to study the collision of a large passenger bus.
[0230] During the collision, the vehicle did not cross, climb over, or straddle the guardrail. The guardrail components and their detachment parts did not intrude into the vehicle's passenger compartment, and their blocking function was in good condition.
[0231] The collision of a large passenger bus with a guardrail involves the following process: vehicle entry, frontal impact, frontal lift, vehicle steering, frontal drift, vehicle landing, and departure from the guardrail. Vehicle entry: The large passenger bus impacts the guardrail at a speed of 80 km / h and an angle of 20°; Frontal impact: The left front headlight area of the vehicle collides with the guardrail's frontal impact surface first, resulting in significant deformation of the steel in the left front headlight area; Frontal lift: Due to the vehicle's inertia and the sloping nature of the concrete guardrail's frontal impact surface, the vehicle's front end lifts; Vehicle steering: As the concrete guardrail is rigid while the vehicle is a semi-rigid structure, the vehicle steering occurs through deformation of the front end area; Vehicle drift: Due to inertia, the left rear wheel of the vehicle drifts; Vehicle landing: After steering, the front end of the vehicle lands on the ground and departs from the guardrail at a certain angle.
[0232] The vehicle successfully exited the collision area, maintaining a normal driving posture without overturning, swerving, or turning around. Furthermore, the wheel tracks after leaving the departure point met the requirements for the guide exit frame, indicating good guiding function. A comparison of the large passenger bus before and after the collision shows that the damage was concentrated on the left side of the vehicle, primarily affecting the bumper, headlights, glass, rear tires, and rear door.
[0233] It should be noted that the damage prediction results for the guardrail under a collision with a large passenger bus (collision conditions: bus weight 14t, speed 80km / h, collision angle 20°) are as follows:
[0234] D max =28.3mm (an increase of 2.2%), VI =861.19mm (a decrease of 0.9%);
[0235] The peak stress of the guardrail decreased to 35.21 MPa (a reduction of 50.2%), and the axial force of the guardrail was 52.06 kN (the safety margin was improved).
[0236] Advantages:
[0237] Structural damage was significantly reduced, with no unit detachment;
[0238] Stable guidance function (vehicle yaw angle θ≤15°).
[0239] The simulation results of a 25-ton truck colliding with a guardrail were used to illustrate the collision of a large truck.
[0240] During the collision, the vehicle did not cross, climb over, or straddle the guardrail. The guardrail components and their detachment parts did not intrude into the vehicle's passenger compartment, and their blocking function was in good condition.
[0241] A large truck colliding with a guardrail involves the following process: vehicle entry, frontal impact, vehicle steering, frontal drift, and departure from the guardrail. Vehicle entry: The large truck collides with the guardrail at a speed of 60 km / h and an angle of 20°; Frontal impact: The right front headlight area of the vehicle collides with the guardrail's frontal impact surface first, resulting in significant deformation of the steel in this area; Vehicle steering: As the concrete guardrail is rigid while the vehicle is a semi-rigid guardrail, the vehicle steers due to deformation in the frontal area; Vehicle drift: Due to inertia, the right rear wheel of the vehicle drifts; Departure from the guardrail: The vehicle departs from the guardrail at a certain angle.
[0242] The maximum lateral dynamic deformation (D) of the guardrail is 31.8 mm, the maximum lateral dynamic displacement extension (W) of the guardrail is 381.8 mm, the maximum dynamic tilt (VI) of the vehicle is 790.13 mm, and the equivalent value of the maximum dynamic tilt (VI) of the vehicle is... n The diameter is 1107.18 mm.
[0243] The vehicle was successfully guided out of the collision, maintaining a normal driving posture without overturning, turning sideways, or making a U-turn. Furthermore, the wheel tracks left after the vehicle left the departure point met the requirements for guiding the vehicle out of the guide frame, indicating that the guiding function was in good condition.
[0244] It should be noted that the damage prediction results for the guardrail under a collision with a large truck (collision conditions: bus weight 25t, speed 60km / h, collision angle 20°) are as follows:
[0245] D max =31.8mm (an increase of 7.4%), VI =790.13mm (a decrease of 1.4%);
[0246] The peak stress of the guardrail was 34.67 MPa (57.1% lower than the previous 80.79 MPa), completely eliminating the risk of connection failure.
[0247] Advantages: After the addition of the bolster beam, the stress of the support block is made more uniform, and the energy absorption rate is increased to over 70%.
[0248] The above technical solutions only embody the preferred technical solutions of the present invention. Any modifications that may be made by those skilled in the art to certain parts thereof embody the principles of the present invention and fall within the protection scope of the present invention.
Claims
1. A method for optimizing guardrail structures based on collision damage simulation prediction, characterized in that, The method includes the following steps: Step 1, Parametric geometric modeling: Based on the design drawings of the guardrail, the geometric dimension parameters of the guardrail are extracted, and a three-dimensional geometric model of the guardrail is built using parametric modeling software. Step 2, Material constitutive model construction: Construct a constitutive model of the material and calculate the strain rate term; Step 3, Multi-condition collision simulation: The simulation conditions are set up, and the simulation process of different conditions is solved based on the explicit dynamic analysis method to calculate the transient response data during the collision process. Step 4, Quantitative assessment of damage: Input the transient response data output from step 3 into the damage model to quantitatively evaluate the vehicle's dynamic camber value and thus determine the vehicle's state after a collision. Step 5, Security Performance Optimization Feedback: Using the maximum lateral dynamic deformation of the guardrail and the dynamic tilt value of the vehicle as constraints, an optimization algorithm is used to find the optimal solution for the geometric dimensions of the guardrail. Step 6: Perform performance analysis on the optimized guardrail. By using simulated collisions, the blocking, buffering, and guiding functions of the optimized guardrail are quantitatively analyzed, and the geometric dimensions of the guardrail are determined based on the quantitative analysis results.
2. The guardrail structure optimization method based on collision damage degree simulation prediction according to claim 1, characterized in that, The geometric parameters in step 1 include: the height of the guardrail, the thickness of the guardrail, the slope of the impact surface of the guardrail, the size of the climbing barrier of the guardrail, and the length of a single section of the guardrail.
3. The guardrail structure optimization method based on collision damage degree simulation prediction according to claim 1, characterized in that, The expression for the material constitutive model in step 2 is as follows: In the formula, σ1 is the rheological stress, and ε is the equivalent plastic strain. To standardize the strain rate, T * Here, A is the normalized temperature, B is the yield strength, n is the hardening modulus, C is the strain rate sensitivity coefficient, and m is the concrete fitting parameter. The parameters A, B, n, C, and m are all derived from experimental measurements of the material.
4. The guardrail structure optimization method based on collision damage degree simulation prediction according to claim 1, characterized in that, The transient response data output by the explicit dynamic analysis method in step 3 includes: the acceleration of the motion equation and the maximum lateral dynamic deformation of the guardrail.
5. The guardrail structure optimization method based on collision damage degree simulation prediction according to claim 4, characterized in that, The equation of motion is: In the formula, M is the mass matrix, and C n Let F be the damping matrix, K be the nonlinear stiffness matrix, and F be the damping matrix. ext This is the collision force vector; The main purpose of the equations of motion is to solve for nodal accelerations. Iterative displacement using the central difference method in, Δt is the duration of acceleration; The contact force between the guardrail and the vehicle is represented by the penalty function method, and its expression is: In the formula, F c Let be the contact force, k be the contact stiffness, and δ be the penetration depth (limited to δ≤0.1mm). The penetration velocity is obtained by differentiating δ. Maximum lateral dynamic deformation D of the guardrail max for: The strain rate term is obtained from the material constitutive model.
6. The guardrail structure optimization method based on collision damage degree simulation prediction according to claim 1, characterized in that, The expression for the damage model in step 4 is: D max =α·E k +β·VI In the formula, D max E represents the maximum lateral dynamic deformation of the guardrail. k VI represents the collision kinetic energy, α represents the vehicle's dynamic camber value, and α / β represent the correlation coefficients of the material / structure, where α is the energy absorption coefficient and β is the structural geometric influence coefficient.
7. The guardrail structure optimization method based on collision damage degree simulation prediction according to claim 1, characterized in that, The optimization algorithms in step 5 include, but are not limited to, response surface methodology or genetic algorithm.
8. The guardrail structure optimization method based on collision damage degree simulation prediction according to claim 1, characterized in that, The process of quantitatively analyzing and optimizing the blocking function of the guardrail in step 6 is as follows: Simulation analysis: Extract the maximum lateral displacement of the vehicle and the maximum dynamic deformation of the guardrail in the simulation, and calculate the blocking efficiency. If η block ≥90% and D vehicle If the distance is ≤0.5m, the blocking function is deemed qualified; In the formula, D vehicle D represents the lateral displacement of the vehicle's center of gravity (m). max η is the maximum lateral dynamic deformation of the guardrail (m). block For blocking efficiency (%).
9. The guardrail structure optimization method based on collision damage degree simulation prediction according to claim 1, characterized in that, The process of quantitatively analyzing and optimizing the buffer function of the guardrail in step 6 includes: Calculate the average deceleration and peak acceleration based on the vehicle acceleration time history curve: In the formula, T is the collision duration, which must satisfy... And a max ≤40g (g is the acceleration due to gravity), a(t) is the time history of vehicle acceleration. This is the average deceleration; Calculate the energy absorption rate of the guardrail: AND absored =∫F c ·δdt In the formula, F c Let E be the contact force, δ be the penetration depth, and E be the contact force. absorbed For the guardrail to absorb energy, the energy absorption rate must reach the total collision kinetic energy (E). k When the buffer reaches 70%, the buffer function is considered qualified.
10. The guardrail structure optimization method based on collision damage degree simulation prediction according to claim 1, characterized in that, The process of quantitatively analyzing and optimizing the guiding function of the guardrail in step 6 is as follows: Calculate the angle (θ) between the vehicle's direction of motion after the collision and the guardrail axis: In the formula, v x and v y These are the longitudinal and lateral velocity components of the vehicle, respectively, and θ is the vehicle yaw angle. If θ ≤ 15°, the guidance function is qualified.