CN111778839A - Composite material filled O-shaped metal plate damper and arrangement and parameter optimization method thereof - Google Patents
Composite material filled O-shaped metal plate damper and arrangement and parameter optimization method thereof Download PDFInfo
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Abstract
The invention provides a composite material filled O-shaped metal plate damper and an arrangement and parameter optimization method thereof, wherein the damper bears load by pin heads (1) with piston rods (3) at two ends of the damper; the starting end of the piston rod is fixed at the pin head, and the tail end of the piston rod is connected with a shape memory piece (5) in a damping cavity of the middle section of the damper through a fastener (4); the damping cavity and the shape memory piece are both filled with a damper (12); the invention consumes energy together by a plurality of structures, and when one element is subjected to fatigue failure, the structure can still ensure the integrity to continue working; and the damper and various supports of the cable-stayed bridge can be jointly arranged into a damping system, so that the transverse and longitudinal reasonable damping of the cable-stayed bridge can be ensured when an earthquake occurs, and the energy consumption efficiency of the damper is improved.
Description
Technical Field
The invention relates to the technical field of buildings, in particular to a composite material filled O-shaped metal plate damper and an arrangement and parameter optimization method thereof.
Background
China is wide in regions and located at junctions of Pacific plates, Asia-European plates and Indian ocean plates, earthquake activities are frequent, and structures are easy to damage under the action of earthquakes, so that a plurality of damping technologies are developed successively in the structural design process. The most common shock absorption means on a bridge is to provide a damper. Common dampers include metal dampers, viscous dampers, friction dampers, and the like, and are respectively faced with the problems of poor durability, complex structure, high price, and the like.
In the aspect of bridge damping device arrangement, more is the device shock attenuation efficiency of independent consideration, and the bridge shock attenuation is arranged to single following the bridge, perhaps uses damping device kind few, arranges simply, is difficult to form reasonable horizontal and vertical shock attenuation power consumption system, consequently construction cost and construction degree of difficulty greatly increased.
The cable-stayed bridge is widely applied due to strong spanning capability and beautiful appearance. Especially in special terrains such as great rivers, gorges and the like. The cable-stayed bridge structure is stressed and mainly transfers load to the bridge tower through the stay cable, so that the rigidity of the cable-stayed bridge tower is very high. The biggest defect of high rigidity of the cable tower is that the response is large under the action of earthquake, and the cable-stayed bridge has high requirement on anti-seismic design and high difficulty.
The optimization parameter targets of the existing damper in a parameter optimization method are uniform, and the existing damper has the defect that the existing damper is not suitable for all types of dampers. While designing the damper, a damper design engineer often does not optimize parameters according to the characteristics of the damper, and selects and uses a general optimization method, so that the parameter setting of the damper cannot be optimized.
Genetic algorithms and simulated annealing algorithms widely used in the optimization field. The genetic algorithm has the defects of poor local search capability, easy trapping in local optimal solution, premature convergence and the like. The simulated annealing algorithm has poor global search capability and is easily influenced by parameters.
Disclosure of Invention
The invention provides a composite material filled O-shaped metal plate damper and an arrangement and parameter optimization method thereof, wherein a plurality of structures consume energy together, and when one element is subjected to fatigue failure, the structure can still ensure the integrity to continue working; and the damper and various supports of the cable-stayed bridge can be jointly arranged into a damping system, so that the transverse and longitudinal reasonable damping of the cable-stayed bridge can be ensured when an earthquake occurs, and the energy consumption efficiency of the damper is improved.
The invention adopts the following technical scheme.
The damper is characterized in that the O-shaped metal plate damper is filled with composite materials, and loads are borne by pin heads (1) with piston rods (3) at two ends of the damper; the starting end of the piston rod is fixed at the pin head, and the tail end of the piston rod is connected with a shape memory piece (5) in a damping cavity of the middle section of the damper through a fastener (4); the damping cavity and the shape memory piece are both filled with a damper (12).
The shape memory member is an O-shaped metal plate molded from a shape memory alloy.
The damper is molded from a copper foam-polyurethane composite and filled with a polyurethane substance at a 50% fill fraction.
The middle section and the rear section of the piston rod are arranged in the damper sleeves at two side parts of the damper and can slide in the damper sleeves along with the movement of the pin head; the damper sleeve comprises a first piston sleeve (6) close to one side of the damping cavity and a second piston sleeve (8) close to one side of the pin head; the first piston sleeve is internally filled with a damping elastomer (7); and a water absorbing piece (9) is filled in the second piston sleeve.
The damping elastic piece is a polyurethane sheet-shaped damping elastomer formed by a mould or a casting polyurethane prepolymer; and waterproof rubber rings (2) are arranged at the outer sides of a first valve port (10) for a piston rod to penetrate through of the first piston sleeve and a second valve port (11) for a piston rod to penetrate through of the second piston sleeve.
The combination of the shape memory part and the damper is an energy consumption core structure of the damper; the energy consumption core structure is connected with the tail end of the piston rod, and when the damper is used for a bridge, if an earthquake occurs, the energy consumption core structure dissipates earthquake energy; when the shape memory body is broken or separated from the piston rod, the damper maintains the function of the energy consumption core structure of the damper by maintaining the strength and stability of the member of the energy consumption core structure.
When the O-shaped metal plate damper filled with the composite material is used for a cable-stayed bridge, the damper and a multidirectional friction pendulum type shock absorption and isolation spherical steel support (B), a transverse shock absorption compound pendulum type friction pendulum support (C), a multidirectional movable spherical steel support (D) and a bidirectional movable steel support (E) of the cable-stayed bridge are jointly combined into a shock absorption system of the cable-stayed bridge; the setting position A of the damper is longitudinally arranged between the bridge tower and the main beam and transversely arranged between the side pier and the main beam; the multidirectional friction pendulum vibration reduction and isolation spherical steel support (B) is arranged between the bottom of the main beam and the pier top of the auxiliary pier, and between the bottom of the main beam and the pier top of the side pier; the transverse damping compound pendulum type friction pendulum support (C) is arranged between the bridge tower and the main beam; the multidirectional movable spherical steel support (D) is arranged between the bridge tower and the main beam; the bidirectional movable steel support (E) is arranged between the side pier and the main beam.
When the O-shaped metal plate damper filled with the composite material is used for a cable-stayed bridge, the damper is formed by a foam copper-polyurethane composite material; the damping elastic piece is a polyurethane sheet-shaped damping elastomer formed by a mould or a casting polyurethane prepolymer;
the parameter optimization method comprises the following steps;
a1, determining a target function, and determining design variables and constraint conditions;
step A2, obtaining experimental data through experimental scheme design;
step A3, establishing an improved response surface model by combining experimental data;
step A4, carrying out precision test through the judgment coefficient;
step a5, optimization by a modified genetic annealing algorithm.
In the step A1, the objective function is to determine the longitudinal displacement of the girder end of the cable-stayed bridge; through DOE experiments, in the technical parameters of the O-shaped metal plate damper filled with the foam copper-polyurethane composite material, according to the influence degree, the design variables are determined to be the polyurethane filling integral, the thickness of the O-shaped metal plate, the sheet spacing of the polyurethane elastomer and the inner diameter of the first piston sleeve in the foam copper-polyurethane composite material, and the constraint conditions are that the control limit value of the longitudinal displacement of the girder end of the cable-stayed bridge girder is 1000mm, the polyurethane filling integral range in the foam copper-polyurethane composite material is [0.3, 0.9], the sheet spacing limit value of the polyurethane elastomer is 100mm, and the thickness limit value of the O-shaped metal plate is 4 mm.
In step a3, by using a multiple quadratic function (Φ (r) ═ 1+ (cr)2Taking a constant c being 1.5 and r being the Euclidean distance between a sample point and any point) as a radial basis function of the kernel function to improve the precision and order of the response surface model;
in step a5, the method specifically includes the following steps;
a501, given algorithm parameters and determining a coding scheme;
step A502, randomly generating an initial population P with the scale of M0Given an initial temperature T0Maximum generation number K;
step A503, evaluating the population P by taking the improved response surface model as a fitness function0The first N (N) with larger fitness is used<M) individuals are added to the memory matrix and adapted to the individuals in the matrixSorting degree, selecting N individuals with larger fitness again to generate a group P1；
Step A504, adopting improved genetic algorithm to pair the population P1Selecting, crossing, mutating, etc., to generate population P2；
Step A505, according to the simulated annealing algorithm pair P improved by the disturbance model and the probability acceptance formula2Computing the population to generate a population P with a size M3；
Step A506, a new population P consisting of M + N genetic individuals and M simulated annealing individuals4Performing niche elimination operation, and taking the first M individuals to form P0；
Step A507, judging whether the maximum generation number is reached, if not, reducing the temperature T and the generation number +1, and returning to the step A503; if so, outputting all non-inferior solutions;
in step a503, the memory matrix adopts a 4-row two-dimensional matrix, the capacity of the memory matrix is limited to 2N, when the recorded individuals exceed 2N, the first 2N individuals with high fitness are reserved, and the rest of individuals are eliminated;
in step A504, the modified genetic algorithm incorporates a chromosome-controlling regulator to optimize population P1A replication probability for individual selection; according to different optimization of dispersion degree in the cluster, improved self-adaptive cross probability P is adoptedcAnd the mutation probability Pm；
In the step a505, the disturbance model adopts the Cauchy distribution depending on the temperature distribution:
x'i＝xi+yi(Bi-Ai)
yi＝Tsgn(u-0.5)[(1+1/T)|2u-1|-1]
in the formula xiIs the i-th component in the current point; u is [0, 1 ]]Uniformly distributed random numbers; [ A ]i,Bi]Is xiIs in the value range of (1), and requires x 'after disturbance'i∈[Ai,Bi](ii) a sgn (x) is a sign function;
the acceptance probability is:
P＝[1-(1-h)ΔE/T]1/(1-h)
in the formula, Δ E is the objective function E (X) of the new point obtained by labor and the objective function E (X) of the current model0) The difference between the two; t is the temperature, and h is 0.8.
The invention has the following beneficial effects:
1. the foam copper-polyurethane composite material is filled in the O-shaped metal plate, the mechanical property of the composite structure is far higher than the sum of the independent actions of the foam copper and the polyurethane material, and the combined action can absorb a large amount of earthquake impact. The polyurethane damping elastomer made of the mould plays a damping role in three modes of materials, structures and friction, and the damping performance of the damper is far superior to that of a traditional metal damper, a viscous damper and a friction damper.
2. The damper is mainly of a filling structure, does not have mechanical structures such as complex hydraulic elements and oil ways, and is convenient to install and maintain. Meanwhile, the polyurethane material has light weight, long service life and low price, and forms good economic benefit.
3. The damper has good internal integrity, and the filling structure enables each component and the material to be tightly combined to consume energy together. When one material or one component is in fatigue damage, the damper cannot suddenly lose efficacy as a whole, and the internal integrity can still be ensured to continue working.
4. The damper is provided with the waterproof device, so that the inside of the damper and the movable valve port are prevented from being rusted, the working efficiency of the damper is ensured, and the service life of the damper is prolonged.
5. The invention considers that the cable-stayed bridge is impacted in different degrees in the transverse and longitudinal directions under the action of an earthquake, provides a damping system which is formed by arranging the damper and various types of supports together, effectively reduces the displacement of a beam end and the relative displacement between a main beam and piers, and can reduce the pier bottom bending moment of side piers and auxiliary piers and the requirements of the transverse resistance of the supports, so that the cable-stayed bridge is reasonably damped in the transverse and longitudinal directions, and the damping efficiency of the bridge is improved.
6. The invention considers that the damping system arranged by the damper is more adaptive by optimizing the material and the process parameters of the damper, and the damping capacity of the damper can be exerted to the maximum extent.
7. The damper parameter optimization method provided by the invention combines a response surface method and a genetic annealing algorithm, and introduces methods such as a memory matrix, improved individual selection, improved crossover, mutation probability, a residual value interpolation function, a disturbance function, an acceptance probability, niche logic and the like, so that the parameter optimization method is more accurate and efficient, and the efficiency of the damper is improved.
Compared with the prior art, the method has the advantages that the damping energy consumption efficiency can be greatly improved, good economic benefits are formed, a reasonable damping system is formed by comprehensive consideration, and an efficient, accurate and applicable damper optimization method is provided.
Drawings
The invention is described in further detail below with reference to the following figures and detailed description:
FIG. 1 is a schematic structural view of a damper according to the present invention;
FIG. 2 is a schematic view of the layout of the damper of the present invention in a cable-stayed bridge;
FIG. 3 is a schematic flow diagram of a genetic annealing algorithm for optimizing the damper parameters of the present invention;
in the figure: 1-a pin head; 2-waterproof rubber ring; 3-a piston rod; 4-a fastener; 5-a shape memory member; 6-a first piston sleeve; 7-a shock absorbing elastomer; 8-a second piston sleeve; 9-a water absorbing member; 10-a first valve port; 11-a second valve port; 12-a damper;
a-setting position of the damper; b, multidirectional friction pendulum seismic reduction and isolation spherical steel support; c-a transverse damping compound pendulum type friction pendulum support; d-a multidirectional movable spherical steel support; e-bidirectional movable steel support.
Detailed Description
As shown in fig. 1-3, a composite material filled O-type sheet metal damper that carries load with pin heads (1) with piston rods (3) at its two ends; the starting end of the piston rod is fixed at the pin head, and the tail end of the piston rod is connected with a shape memory piece (5) in a damping cavity of the middle section of the damper through a fastener (4); the damping cavity and the shape memory piece are both filled with a damper (12).
The shape memory member is an O-shaped metal plate molded from a shape memory alloy.
The damper is molded from a copper foam-polyurethane composite and filled with a polyurethane substance at a 50% fill fraction.
The middle section and the rear section of the piston rod are arranged in the damper sleeves at two side parts of the damper and can slide in the damper sleeves along with the movement of the pin head; the damper sleeve comprises a first piston sleeve (6) close to one side of the damping cavity and a second piston sleeve (8) close to one side of the pin head; the first piston sleeve is internally filled with a damping elastomer (7); and a water absorbing piece (9) is filled in the second piston sleeve.
The damping elastic piece is a polyurethane sheet-shaped damping elastomer formed by a mould or a casting polyurethane prepolymer; and waterproof rubber rings (2) are arranged at the outer sides of a first valve port (10) for a piston rod to penetrate through of the first piston sleeve and a second valve port (11) for a piston rod to penetrate through of the second piston sleeve.
The combination of the shape memory part and the damper is an energy consumption core structure of the damper; the energy consumption core structure is connected with the tail end of the piston rod, and when the damper is used for a bridge, if an earthquake occurs, the energy consumption core structure dissipates earthquake energy; when the shape memory body is broken or separated from the piston rod, the damper maintains the function of the energy consumption core structure of the damper by maintaining the strength and stability of the member of the energy consumption core structure.
When the O-shaped metal plate damper filled with the composite material is used for a cable-stayed bridge, the damper and a multidirectional friction pendulum type shock absorption and isolation spherical steel support (B), a transverse shock absorption compound pendulum type friction pendulum support (C), a multidirectional movable spherical steel support (D) and a bidirectional movable steel support (E) of the cable-stayed bridge are jointly combined into a shock absorption system of the cable-stayed bridge; the setting position A of the damper is longitudinally arranged between the bridge tower and the main beam and transversely arranged between the side pier and the main beam; the multidirectional friction pendulum vibration reduction and isolation spherical steel support (B) is arranged between the bottom of the main beam and the pier top of the auxiliary pier, and between the bottom of the main beam and the pier top of the side pier; the transverse damping compound pendulum type friction pendulum support (C) is arranged between the bridge tower and the main beam; the multidirectional movable spherical steel support (D) is arranged between the bridge tower and the main beam; the bidirectional movable steel support (E) is arranged between the side pier and the main beam.
When the O-shaped metal plate damper filled with the composite material is used for a cable-stayed bridge, the damper is formed by a foam copper-polyurethane composite material; the damping elastic piece is a polyurethane sheet-shaped damping elastomer formed by a mould or a casting polyurethane prepolymer;
the parameter optimization method comprises the following steps;
a1, determining a target function, and determining design variables and constraint conditions;
step A2, obtaining experimental data through experimental scheme design;
step A3, establishing an improved response surface model by combining experimental data;
step A4, carrying out precision test through the judgment coefficient;
step a5, optimization by a modified genetic annealing algorithm.
In the step A1, the objective function is to determine the longitudinal displacement of the girder end of the cable-stayed bridge; through DOE experiments, in the technical parameters of the O-shaped metal plate damper filled with the foam copper-polyurethane composite material, according to the influence degree, the design variables are determined to be the polyurethane filling integral, the thickness of the O-shaped metal plate, the sheet spacing of the polyurethane elastomer and the inner diameter of the first piston sleeve in the foam copper-polyurethane composite material, and the constraint conditions are that the control limit value of the longitudinal displacement of the girder end of the cable-stayed bridge girder is 1000mm, the polyurethane filling integral range in the foam copper-polyurethane composite material is [0.3, 0.9], the sheet spacing limit value of the polyurethane elastomer is 100mm, and the thickness limit value of the O-shaped metal plate is 4 mm.
In step a3, by using a multiple quadratic function (Φ (r) ═ 1+ (cr)2Taking a constant c being 1.5 and r being the Euclidean distance between a sample point and any point) as a radial basis function of the kernel function to improve the precision and order of the response surface model;
in step a5, the method specifically includes the following steps;
a501, given algorithm parameters and determining a coding scheme;
step A502, randomly generating initial seeds with the scale of MGroup P0Given an initial temperature T0Maximum generation number K;
step A503, evaluating the population P by taking the improved response surface model as a fitness function0The first N (N) with larger fitness is used<M) adding the individuals into a memory matrix, sorting the fitness of the individuals in the matrix, and selecting N individuals with higher fitness again to generate a group P1；
Step A504, adopting improved genetic algorithm to pair the population P1Selecting, crossing, mutating, etc., to generate population P2；
Step A505, according to the simulated annealing algorithm pair P improved by the disturbance model and the probability acceptance formula2Computing the population to generate a population P with a size M3；
Step A506, a new population P consisting of M + N genetic individuals and M simulated annealing individuals4Performing niche elimination operation, and taking the first M individuals to form P0；
Step A507, judging whether the maximum generation number is reached, if not, reducing the temperature T and the generation number +1, and returning to the step A503; if so, outputting all non-inferior solutions;
in step a503, the memory matrix adopts a 4-row two-dimensional matrix, the capacity of the memory matrix is limited to 2N, when the recorded individuals exceed 2N, the first 2N individuals with high fitness are reserved, and the rest of individuals are eliminated;
in step A504, the modified genetic algorithm incorporates a chromosome-controlling regulator to optimize population P1A replication probability for individual selection; according to different optimization of dispersion degree in the cluster, improved self-adaptive cross probability P is adoptedcAnd the mutation probability Pm；
In the step a505, the disturbance model adopts the Cauchy distribution depending on the temperature distribution:
x'i＝xi+yi(Bi-Ai)
yi＝Tsgn(u-0.5)[(1+1/T)|2u-1|-1]
in the formula xiIs the first in the current pointAn i component; u is [0, 1 ]]Uniformly distributed random numbers; [ A ]i,Bi]Is xiIs in the value range of (1), and requires x 'after disturbance'i∈[Ai,Bi](ii) a sgn (x) is a sign function;
the acceptance probability is:
P＝[1-(1-h)ΔE/T]1/(1-h)
in the formula, Δ E is the objective function E (X) of the new point obtained by labor and the objective function E (X) of the current model0) The difference between the two; t is the temperature, and h is 0.8.
In the embodiment, the purpose of full-bridge transverse and longitudinal reasonable shock absorption is achieved by arranging the dampers and the shock absorption supports with two specifications, and the shock absorption system has the advantages of strong energy consumption, uniform stress, multidirectional shock absorption and convenience in installation.
Example 1:
in this example, the material of the O-shaped metal plate is a memory alloy that satisfies the conditions according to the design requirements; the thickness and the strength of the damping device are required to meet the requirement that when the damping device is impacted by earthquake, the piston rod moves stably in the damper, and the O-shaped metal plate keeps the deformation elasticity; the radius of the first piston steel sleeve is slightly smaller than the inner wall of the first piston steel sleeve.
The contact surface of the piston rod and the O-shaped metal plate is transversely fixed by 3-6 bolts, the total cross-sectional area of the bolts is about 1/6 of the contact area, the internal integrity of the damper is ensured, and meanwhile, the strength of the metal plate cannot be damaged.
The foam copper-polyurethane composite material is filled inside and outside the O-shaped metal plate, so that the working stability of the metal plate is improved, the internal integrity of the damper is ensured when the metal plate is in fatigue fracture or is separated from the piston rod, and the damper is ensured to continue to work.
The foam copper-polyurethane composite material adopted in the invention has strong energy consumption capability and low resilience, and the mechanical property of the formed composite structure is greatly enhanced after the O-shaped metal plate is filled.
The polyurethane shock-absorbing elastomer is made into an elastomer with a concentric semicircle section by a mould, and the elastomer is assembled into a complete polyurethane shock-absorbing elastomer after being arranged in a damper.
When an earthquake occurs, the polyurethane damping elastomer absorbs the longitudinal impact of the earthquake through the polyurethane material and the sheet structure, and meanwhile, the friction force between the polyurethane damping elastomer and the piston rod also participates in energy consumption.
In the embodiment, the second piston steel sleeve and the waterproof rubber ring are arranged, so that the piston rod is kept dry in the displacement process of the first valve port, and the mechanical property of a polyurethane material in the damper is ensured. The water absorbing material adopts a drying agent.
In the embodiment, the shock absorption system of the cable-stayed bridge consists of a foam copper-polyurethane composite material filled O-shaped metal plate damper, a multidirectional friction pendulum shock absorption and isolation spherical steel support, a transverse shock absorption compound pendulum type friction pendulum support, a multidirectional movable spherical steel support and a bidirectional movable steel support.
The shock attenuation system passes through the attenuator and the support setting, at the shock attenuation in-process, reduces the displacement of beam-ends and the relative displacement between girder and the mound, also can reduce the side mound simultaneously and assist mound pier bottom bending moment and the horizontal resistance demand of support.
In the embodiment, the O-shaped metal plate damper filled with the foam copper-polyurethane composite material is longitudinally arranged between the bridge tower and the main beam and transversely arranged between the side pier and the main beam; the multidirectional friction pendulum vibration reduction and isolation spherical steel support is arranged between the bottom of the main beam and the pier top of the auxiliary pier, and between the bottom of the main beam and the pier top of the side pier; the transverse damping compound pendulum type friction pendulum support is arranged between the bridge tower and the main beam; the multidirectional movable spherical steel support is arranged between the bridge tower and the main beam; the bidirectional movable steel support is arranged between the side pier and the main beam.
When an earthquake occurs, the multidirectional friction pendulum vibration reduction and isolation spherical steel support reduces the impact of the earthquake in all directions and reduces the pier bottom bending moment borne by the auxiliary pier through friction force and swing under the action of the earthquake; the transverse damping compound pendulum type friction pendulum support is easy to install, high in height and large in swing period under the action of an earthquake, and can meet large displacement; the shock absorption system is characterized in that a foam copper-polyurethane composite material is filled in an O-shaped metal plate damper to absorb shock together with various types of supports, and a limiting device is not arranged.
The damping system is not provided with a limiting device, the bending moment of the pier bottom of the cable-stayed bridge is relatively small, the displacement of the girder end of the girder is relatively large, and the objective function is determined as the minimum longitudinal displacement of the girder end of the girder.
Example 2:
in parameter optimization, in this example, after the objective function is determined, experimental Design (DOE) is performed by using a method of optimizing a plurality of experimental factors by using an orthogonal matrix, and the influence of the experimental factors on the objective function is determined, so as to determine design variables and constraint conditions. The DOE can determine the optimum level combination under all the factors and corresponding levels through a small number of experiments.
When an objective function is determined, the DOE takes the longitudinal displacement of the girder end as the objective function, and selects the foam copper-polyurethane composite material to fill the technological parameters of the O-shaped metal plate damper, such as the porosity of the foam copper-polyurethane composite material, the filling integral of polyurethane in the foam copper-polyurethane composite material, the thickness of the O-shaped metal plate, the thickness of a polyurethane elastomer sheet, the distance between the polyurethane elastomer sheets and the like, as many as possible, so as to obtain four parameters with the highest influence degree as design variables.
In the specific operation, Design-Expert software is used for BBD (Box-BehnkenDesign) experimental scheme Design, a Box-Behnken matrix sampling method is used for determining 30 groups of experimental schemes, SAP2000 finite element calculation is carried out on each group of experimental schemes, and beam end displacement corresponding to 30 groups of experimental sample points is obtained.
And selecting the front 25 groups of experimental sample points obtained through finite element calculation, and performing regression fitting on a second-order polynomial by combining experimental results to further obtain a second-order response surface model of longitudinal displacement of the girder end, polyurethane filling integral in the foam copper-polyurethane composite material, thickness of an O-shaped metal plate, inner diameter of a first piston steel sleeve and sheet-shaped spacing of a polyurethane elastomer.
The response surface function model is:
in the formula
β upper and lower limits of the design space, respectively0、βn、βnm、βnnAll can be obtained by the least square method.
Further, by using a multiple quadratic function phi (r) ═ 1+ (cr)2The constant c is 1.5, and r is the euclidean distance between a sample point and any point) is taken as a radial basis function of the kernel function to improve the accuracy and the order of the response surface model. And 5 groups of unused experimental sample points are utilized to respectively carry out second-order response surface model and finite element calculation, a residual value interpolation function of the target function is constructed by utilizing the residual error between the two experimental sample points and the multiple quadratic function, and the residual value interpolation function is added with the second-order response surface model to obtain the improved second-order response surface model with higher accuracy.
Further, using multiple fitting coefficients R2For the improved response surface model precision monitoring, when the multiple fitting coefficient is larger than 0.95, the improved precision requirement is met.
In this example, Genetic Algorithm (GA) was originally proposed by john holland in the united states in the 70's 20 th century, and the algorithm was designed based on the rules of evolution of organisms in nature. The method is a calculation model of the biological evolution process for simulating natural selection and genetic mechanism of Darwinian biological evolution theory, and is a method for searching an optimal solution by simulating the natural evolution process.
In this example, the idea of simulated annealing algorithm (SA) was first proposed by n.metropolis et al in 1953, but it was not until 1983 that skerkpatrick et al applied the simulated annealing algorithm to combinatorial optimization as a new optimization method. The simulated annealing algorithm is analogous to the process of annealing a physical solid from a high temperature to a low temperature to reach a minimum free energy state. The biggest difference with other optimization methods is that the simulated annealing algorithm can accept infeasible solutions with certain probability, so that the simulated annealing algorithm has the searching capability of continuously searching for the optimal point from the local optimal point to the global optimal point.
In this example, niche elimination logic was introduced into the genetic annealing algorithm (NGSA). In biology, a particular environment and the tissues it lives in are called niches (niches), while some tissues with common characteristics are called species. The basic genetic algorithm adopts a random mode when individuals mate, which enhances the searching capability of a problem solution space, but also brings the problems of effectiveness of mating, low optimization efficiency and the like. To solve these problems, niche technology is introduced in basic genetic algorithms. The method not only can effectively ensure the diversity of solutions in the group, but also has obvious effects in the aspects of convergence speed, calculation precision, global search capability and the like of problem solving, and is an effective method.
In this example, a modified genetic annealing algorithm (NGSA) was used, and the implementation consisted of three parts: the selection of excellent individuals is realized through a concentration control mechanism of the niche, then a better group is generated through the evolution operation (emphasizing on global search) of the adaptive genetic algorithm, the optimization and adjustment of gene individuals are carried out through the improved simulated annealing operation (emphasizing on local search), and the operation process is iterated repeatedly until the termination condition is met. The algorithm idea aims at improving the performance of the algorithm from the search angle of the global optimal solution and the evolution speed of the algorithm.
Specifically to this example, the initial step of the improved genetic annealing algorithm involves (1) randomly generating an initial population P of size M0Given an initial temperature T0Maximum generation number K; (2) evaluating group P by taking improved response surface model as fitness function0The first N (N) with larger fitness is used<M) adding the individuals into a memory matrix, sorting the fitness of the individuals in the matrix, and selecting N individuals with higher fitness again to generate a group P1(ii) a (3) Selecting, crossing, mutating, etc. by genetic algorithm to generate population P2(ii) a (4) Simulated annealing algorithm pair P improved by disturbance model and probability acceptance formula2Computing the population to generate a population P with a size M3(ii) a (5) For new population P consisting of M + N genetic individuals and M simulated annealing individuals4Performing niche elimination operation, and taking the first M individuals to form P0(ii) a (6) Judging whether the maximum generation number is reached, if not, reducing the temperature T, and returning to the step (2) after the generation number is plus 1; if so, outputtingAll non-inferior solutions.
Wherein, the initial temperature adopts a formula:
in the formula, | Δ fmaxI is the maximum target function difference between two bodies, PrFor the structure probability, generally [0.7, 0.9] is selected]。
In this example, the memory Matrix is a 4-row two-dimensional Matrix, denoted as Matrix1, and stores four design variables, respectively, and the Matrix row numbers represent the numbers. The memory matrix capacity is limited to 2N. And (4) reordering every time when a new individual is recorded, and keeping the first 2N individuals with higher fitness and eliminating the rest individuals when the recorded individuals exceed 2N. And selecting N individuals with higher fitness again from the 2N individuals and outputting the individuals to the next step.
When the genetic algorithm selects individuals, in order to perform a dynamic selective replication operation, a replication probability needs to be set for each individual in a population, and the probability formula is as follows:
in the formula PiIs the probability that the ith chromosome is replicated; psizeSetting the total number for the population as N; fi' is the dynamic scaled fitness of chromosome i; fj' is the dynamic scaled fitness of chromosome j.
Further, the relation between the introduced regulating factors for controlling chromosome diversity and the dynamic scaling fitness is as follows:
wherein GEN is a genetic algebra of a genetic algorithm and is set as 100; r is inherited to the r generation; to control the regulatory factor for chromosomal diversity, 10 was set.
In this example, an improved adaptive crossover probability P is used based on different optimizations based on the degree of dispersion in the clusterscAnd the mutation probability PmThe more concentrated the population fitness value distribution is, the lower the population diversity is, the less the cross probability self-adaptation is, the faster the algorithm speed is, and meanwhile, the more the variation probability self-adaptation is increased, so that the algorithm better gets rid of local extreme values, and the global optimal solution is obtained. The formula is as follows:
in the formula fmaxIs the maximum fitness value of the population, favgIs a population average fitness value; k is a radical of1、k2To adaptively control the parameters.
In this example, a Cauchy distribution dependent on the temperature distribution is used:
x'i＝xi+yi(Bi-Ai)
yi＝Tsgn(u-0.5)[(1+1/T)|2u-1|-1]
in the formula xiIs the i-th component in the current point; u is [0, 1 ]]Uniformly distributed random numbers; [ A ]i,Bi]Is xiIs in the value range of (1), and requires x 'after disturbance'i∈[Ai,Bi](ii) a sgn (X) is a sign function. The model can be searched in a large range under the condition of high temperature, and the search range is greatly reduced under the condition of low temperature, so that the convergence speed is obviously accelerated.
In this example, the acceptance probability is adopted as:
P＝[1-(1-h)ΔE/T]1/(1-h)
in the formula, Δ E is the objective function E (X) of the new point obtained by labor and the objective function E (X) of the current model0) The difference between the two; t is the temperature, and h is 0.8.
In performing the calculation, the moduleThe quasi-annealing algorithm adopts a proportional attenuation annealing cooling formula as follows: t isn＝aTn-1. In the formula, the annealing rate a was 0.85, and the number of internal cycles was 10.
And when the iteration times of the algorithm reach the set maximum generation number, returning the best individual optimal solution to output, and ending the algorithm.
Claims (10)
1. O type metal sheet attenuator is filled to combined material, its characterized in that: the damper bears the load with pin heads (1) with piston rods (3) at its two ends; the starting end of the piston rod is fixed at the pin head, and the tail end of the piston rod is connected with a shape memory piece (5) in a damping cavity of the middle section of the damper through a fastener (4); the damping cavity and the shape memory piece are both filled with a damper (12).
2. A composite filled O-ring metal plate damper as claimed in claim 1 wherein: the shape memory member is an O-shaped metal plate molded from a shape memory alloy.
3. A composite filled O-ring metal plate damper as claimed in claim 2 wherein: the damper is molded from a copper foam-polyurethane composite and filled with a polyurethane substance at a 50% fill fraction.
4. A composite filled O-ring metal plate damper as claimed in claim 2 wherein: the middle section and the rear section of the piston rod are arranged in the damper sleeves at two side parts of the damper and can slide in the damper sleeves along with the movement of the pin head; the damper sleeve comprises a first piston sleeve (6) close to one side of the damping cavity and a second piston sleeve (8) close to one side of the pin head; the first piston sleeve is internally filled with a damping elastomer (7); and a water absorbing piece (9) is filled in the second piston sleeve.
5. The composite filled O-ring metal plate damper of claim 4 wherein: the damping elastic piece is a polyurethane sheet-shaped damping elastomer formed by a mould or a casting polyurethane prepolymer; and waterproof rubber rings (2) are arranged at the outer sides of a first valve port (10) for a piston rod to penetrate through of the first piston sleeve and a second valve port (11) for a piston rod to penetrate through of the second piston sleeve.
6. The composite filled O-ring metal plate damper of claim 4 wherein: the combination of the shape memory part and the damper is an energy consumption core structure of the damper; the energy consumption core structure is connected with the tail end of the piston rod, and when the damper is used for a bridge, if an earthquake occurs, the energy consumption core structure dissipates earthquake energy; when the shape memory body is broken or separated from the piston rod, the damper maintains the function of the energy consumption core structure of the damper by maintaining the strength and stability of the member of the energy consumption core structure.
7. The arrangement method of the composite material filled O-shaped metal plate damper is characterized in that: when the composite material filled O-shaped metal plate damper is used for a cable-stayed bridge, the damper is combined with a multidirectional friction pendulum shock absorption and isolation spherical steel support (B), a transverse shock absorption compound pendulum type friction pendulum support (C), a multidirectional movable spherical steel support (D) and a bidirectional movable steel support (E) of the cable-stayed bridge to form a shock absorption system of the cable-stayed bridge;
the setting position A of the damper is longitudinally arranged between the bridge tower and the main beam and transversely arranged between the side pier and the main beam; the multidirectional friction pendulum vibration reduction and isolation spherical steel support (B) is arranged between the bottom of the main beam and the pier top of the auxiliary pier, and between the bottom of the main beam and the pier top of the side pier; the transverse damping compound pendulum type friction pendulum support (C) is arranged between the bridge tower and the main beam; the multidirectional movable spherical steel support (D) is arranged between the bridge tower and the main beam; the bidirectional movable steel support (E) is arranged between the side pier and the main beam.
8. A parameter optimization method for the composite material filled O-shaped metal plate damper; the method is characterized in that: when the composite material filled O-shaped metal plate damper as claimed in claim 5 is used for a cable-stayed bridge, the damper is formed by a foam copper-polyurethane composite material; the damping elastic piece is a polyurethane sheet-shaped damping elastomer formed by a mould or a casting polyurethane prepolymer;
the parameter optimization method comprises the following steps;
a1, determining a target function, and determining design variables and constraint conditions;
step A2, obtaining experimental data through experimental scheme design;
step A3, establishing an improved response surface model by combining experimental data;
step A4, carrying out precision test through the judgment coefficient;
step a5, optimization by a modified genetic annealing algorithm.
9. The parameter optimization method of the composite material filled O-shaped metal plate damper according to claim 8; the method is characterized in that: in the step A1, the objective function is to determine the longitudinal displacement of the girder end of the cable-stayed bridge; through DOE experiments, in the technical parameters of the O-shaped metal plate damper filled with the foam copper-polyurethane composite material, according to the influence degree, the design variables are determined to be the polyurethane filling integral, the thickness of the O-shaped metal plate, the sheet spacing of the polyurethane elastomer and the inner diameter of the first piston sleeve in the foam copper-polyurethane composite material, and the constraint conditions are that the control limit value of the longitudinal displacement of the girder end of the cable-stayed bridge girder is 1000mm, the polyurethane filling integral range in the foam copper-polyurethane composite material is [0.3, 0.9], the sheet spacing limit value of the polyurethane elastomer is 100mm, and the thickness limit value of the O-shaped metal plate is 4 mm.
10. The parameter optimization method of the composite material filled O-shaped metal plate damper according to claim 8; the method is characterized in that: in step a3, by using a multiple quadratic function (Φ (r) ═ 1+ (cr)2Taking a constant c being 1.5 and r being the Euclidean distance between a sample point and any point) as a radial basis function of the kernel function to improve the precision and order of the response surface model;
in step a5, the method specifically includes the following steps;
a501, given algorithm parameters and determining a coding scheme;
step A502, randomly generating an initial population P with the scale of M0Given an initial temperature T0Maximum generation number K;
step A503, evaluating the population P by taking the improved response surface model as a fitness function0The first N (N) with larger fitness is used<M) adding the individuals into a memory matrix, sorting the fitness of the individuals in the matrix, and selecting N individuals with higher fitness again to generate a group P1；
Step A504, adopting improved genetic algorithm to pair the population P1Selecting, crossing, mutating, etc., to generate population P2；
Step A505, according to the simulated annealing algorithm pair P improved by the disturbance model and the probability acceptance formula2Computing the population to generate a population P with a size M3；
Step A506, a new population P consisting of M + N genetic individuals and M simulated annealing individuals4Performing niche elimination operation, and taking the first M individuals to form P0；
Step A507, judging whether the maximum generation number is reached, if not, reducing the temperature T and the generation number +1, and returning to the step A503; if so, outputting all non-inferior solutions;
in step a503, the memory matrix adopts a 4-row two-dimensional matrix, the capacity of the memory matrix is limited to 2N, when the recorded individuals exceed 2N, the first 2N individuals with high fitness are reserved, and the rest of individuals are eliminated;
in step A504, the modified genetic algorithm incorporates a chromosome-controlling regulator to optimize population P1A replication probability for individual selection; according to different optimization of dispersion degree in the cluster, improved self-adaptive cross probability P is adoptedcAnd the mutation probability Pm；
In the step a505, the disturbance model adopts the Cauchy distribution depending on the temperature distribution:
x'i＝xi+yi(Bi-Ai)
yi＝Tsgn(u-0.5)[(1+1/T)|2u-1|-1]
in the formula xiIs the i-th component in the current point; u is [0, 1 ]]Uniformly distributed random numbers; [ A ]i,Bi]Is xiIs in the value range of (1), and requires x 'after disturbance'i∈[Ai,Bi](ii) a sgn (x) is a sign function;
the acceptance probability is:
P＝[1-(1-h)ΔE/T]1/(1-h)
in the formula, Δ E is the objective function E (X) of the new point obtained by labor and the objective function E (X) of the current model0) The difference between the two; t is the temperature, and h is 0.8.
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