CN101667221A - Method for determining dual-layer top cover of motor coach with top-positioned gas cylinder - Google Patents
Method for determining dual-layer top cover of motor coach with top-positioned gas cylinder Download PDFInfo
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Abstract
A method for determining a dual-layer top cover of a motor coach with a top-positioned gas cylinder comprises topology optimization, initial structure design, section optimization, anti-overturn stability analysis and fatigue analysis. According to the design requirement, the topology optimization design based on conditions such as bearing capability, shape, power distribution and the like is carried out, thus obtaining an initial space structure of the top cover; subsequently, the section optimization is carried out to the initial space structure and the structure improving design is carriedout so that the improved structure meets the low-order vibration performance and static performance on stiffness and strength; subsequently, the anti-overturn analysis and fatigue analysis are carriedout on the improved structure so as to ensure nonoccurrence of gas leakage problem due to damaged gas cylinder under the overturn working condition of the motor coach with top-positioned gas cylinder, ensure the fatigue durability of the structure of the whole coach, and ensure that the top cover of the motor coach with the top-positioned gas cylinder meets the low-order vibration performance, static performance on stiffness and strength and safety and durability under the overturn working condition. The method simplifies the workload, improves the success rate of product development and shortens development period.
Description
Technical field
The invention belongs to mechanical design field, relate to the motor bus method for designing, especially under the prerequisite of guaranteeing motor bus relevant art index, design the lightest cap structure.
Background technology
The method for designing of at present external motor coach with top-positioned gas cylinder is: do structure primary design → Finite Element Method according to the reference sample car and make cae analysis and make improvements design → sample car design → performance test → architecture advances, the method for designing of domestic motor coach with top-positioned gas cylinder is: do structure primary design → sample car design → performance test → architecture advances according to the reference sample car.The initial configuration method for designing of these two kinds of methods depends on the experience with reference to sample car and designer to a great extent, and profile, structural arrangement and Performance Match all are to contrast with reference to sample car, and have subjectivity and empirical.It is strong excessively that structure often appears in the top-positioned gas cylinder top cover that this method is designed, and do not meet the lightweight requirements of vehicle body, perhaps is exactly that security is not enough, invaded the leakage security problem that causes because of rollover as the top-positioned gas cylinder mounting structure.On the other hand, compare with traditional passenger vehicle, top-positioned gas cylinder class motor bus is owing to the gas cylinder overhead makes the center of gravity of himself higher, so such passenger vehicle is than the easier rollover of traditional passenger vehicle, and rollover harm is bigger.Therefore, the factor that the design of motor coach with top-positioned gas cylinder need be considered is more, make passenger vehicle and the cap structure designed satisfy numerous technical requirements, and will make the construction cycle the shortest, needs the new method for designing of research.
Summary of the invention
Safety issues such as, gas cylinder leakage more repeatedly for fear of the structural design that the motor coach with top-positioned gas cylinder method for designing that adopts is at present both at home and abroad brought the invention provides a kind of motor coach with top-positioned gas cylinder construction design method based on topological optimization, section optimal, roll stability analysis and analysis of fatigue.
Basic procedure of the present invention is: do structural Topology Optimization analysis → structure primary design → section optimal analysis and architecture advances → rollover analysis and architecture advances → analysis of fatigue → sample car design → performance test → architecture advances according to design object.
The present invention address the above problem and propose at the motor coach with top-positioned gas cylinder method for designing be: according to designing requirement, on the basis that comprises conditions such as load-bearing capacity, profile, power layout, adopt topology optimization design, obtain the preliminary space structure of top cover, then this preliminary space structure is carried out section optimal and carry out architecture advances design, make the structure after the improvement satisfy low order vibration performance and static stiffness performance; Turn on one's side and analyze and analysis of fatigue improving structure again, guarantee that motor coach with top-positioned gas cylinder can not take place under the rollover operating mode that gas cylinder destroys and the gas leakage problem that causes and the structural fatigue permanance of car load; Guarantee that designed motor coach with top-positioned gas cylinder top cover satisfies security and the permanance under low order vibration performance, static stiffness performance, the rollover operating mode.
Further, in the topology optimization design step, finite element model adopts plate, beam assembled unit, adopts the higher relatively plate unit based on quadrilateral of precision for the top cover that participates in topological optimization, adopt rigid element with top cover and gusset, precedingly enclose, after closed structure link to each other;
In order to make the topological analysis result can satisfy the requirement of body frame strength and stiffness under each operating mode more all sidedly, this topological analysis has carried out considering crooked operating mode, four kinds of unsettled twisting conditions, left and right turning operating mode, damped condition, and the totally 10 kinds of operating modes of rollover operating mode to the right respectively left;
Crooked operating mode, four kinds of unsettled twisting conditions, left and right turning operating mode and damped conditions, the respective nodes place that all load that bus body is born and constraint are mapped to basic structure is applied on the corresponding node in the mode of centre-point load; Vehicle body load comprises: vehicle body deadweight, passenger's quality, power assembly quality, seat quality.
In the section optimal step, consider the body lightening target, objective function is elected the body quality minimum as.
In the section optimal step, dimension synthesis is followed following principle:
(1) at first takes turns optimization result under five kinds of operating modes of unsettled strength optimization based on the optimization of bench test torsional rigidity, bending strength optimization and one;
(2) contrast initial value, by (1) calculate average-size and initial value differ 10% and revert to initial value with interior parts;
(3), will strengthen than the sectional dimension of sensitive compressible members body frame mode according to mode sensitivity analysis result;
(4) optimize and the strength optimization result according to the bench test torsional rigidity, pay close attention to the wherein more parts of size increase, reducing of the sectional dimension of these parts need be prudent;
(5) mode, rigidity, the intensity of model is checked repeatedly behind the pair cross-section modification of dimension, until satisfying every index.
In the analysis of rollover collision simulation each assembly of vehicle body is all adopted the modeling of plate unit, propons, back axle and tire also adopt the modeling of plate unit, have only the anti-space frame of invading of living space ladder-shaped frame and top cover hydrogen pipeline to adopt the beam element modeling;
Set up ladder-shaped frame with beam element and replace distortion rule, in order to simulation passenger living space; For guaranteeing that distortion rule do not have relative motion with respect to floor in the rollover process, four nodes and the body transom of ladder-shaped frame is rigidly connected;
For investigating the security in the rollover collision of top cover gas cylinder pipeline and gas cylinder, according to the geometric data of actual measurement gas cylinder intake line, set up the anti-space of invading of top cover gas cylinder pipeline, anti-high-low limit point of invading space frame is rigidly connected with corresponding roof rai;
The rollover collision is reorganized and outfit at car load and is carried out simulation analysis under the load situation.
In the analysis of fatigue step, the analysis of fatigue finite element model is selected the plate unit for use; Part quality such as quality, gas cylinder, fuel battery engines and the power system relevant device of people and seat, air-conditioning are added to relevant position on the vehicle body by the mode of mass unit; In carrying out body structure transient state dynamic response, must consider carefully by the caused dynamic effect of lumped mass; For better load condition that is virtually reality like reality, the some of them mass unit affacts on the pairing node in actual installation position by multi-point constraint unit rbe3; The position that vehicle body is connected with suspension is reduced to 6 suspension point of excitation;
Import as the external world with road excitation, to tire, suspension, the hard and soft property multi-body system that vehicle body is formed is carried out dynamic simulation, adopt the SFORCE power element among the ADAMS to set up tire model, adopt the acting force between IMPACT impulsive force functional simulation tire and the ground in the modeling; Hard and soft many phantoms of the property type that includes tire, suspension and body frame composition is carried out road traveling emulation, extract the time history of vehicle body and suspension tie point place power by simulation result; The power that during analysis suspension is affacted vehicle body is simplified, and only extracts spring and vibroshock and acts on z on the vehicle body to the time history of power, and it is added and be used as the pumping signal that acts on the body mount point;
Concerning the car load auto model, the road surface input should be considered the coherence of left and right sides vehicle and the time delay of front and back vehicle, only consider the effect of vertical load in the analysis, do not consider the influence of side direction, the road excitation of left and right wheels is thought identical, and the suffered road excitation of trailing wheel can be thought the time delay of front-wheel institute excited target.
The invention has the beneficial effects as follows: can make the cap structure of designing reach Optimum Matching, and can guarantee the security of gas cylinder under the rollover operating mode in structural arrangement, bar cross section type and size.This method has not only been simplified workload, and has improved the product development success ratio, shortens the construction cycle.
Description of drawings
Fig. 1 is the schematic flow sheet of the inventive method.
Fig. 2 is that density sill value is 0.28 o'clock top cover upper strata topological optimization figure as a result.
Fig. 3 is that density sill value is etale topology figure as a result under 0.28 o'clock the top cover.
Fig. 4 is that the up and down two-layer beam column spare of top cover is arranged total figure.
Fig. 5 is according to the topological girder construction placement scheme figure of lower floor of top cover as a result.
Fig. 6 is according to the anterior girder construction placement scheme of topological top cover as a result figure.
Fig. 7 is according to the topological girder construction of back part of top cover as a result placement scheme figure.
Fig. 8 is the top cover upper strata girder construction placement scheme figure that obtains according to topological result.
Fig. 9 optimizes comprehensive back each member section change in size figure of body frame (member of comprehensive back cross section chap).
Figure 10 optimizes comprehensive back each member section change in size figure of body frame (member that cross section, comprehensive back attenuates).
Figure 11 is that car load finite element model figure is analyzed in the rollover of top-positioned gas cylinder bi-layer tip cap motor bus.
Figure 12 is passenger's living space illustraton of model.
Figure 13 is the anti-spatial model figure that invades of gas cylinder pipeline.
Embodiment
The present invention is further illustrated below in conjunction with the accompanying drawing illustrated embodiment.
Fig. 1 is the schematic flow sheet of the inventive method, mainly comprises: do structural Topology Optimization analysis → structure primary design → section optimal analysis and architecture advances → rollover analysis and architecture advances → analysis of fatigue → sample car design → performance test → architecture advances according to design object.
What the present invention proposed at motor coach with top-positioned gas cylinder top cover method for designing is: according to designing requirement, on the basis that comprises conditions such as load-bearing capacity, profile, power layout, adopt topology optimization design, obtain the preliminary space structure of top cover, then this preliminary space structure is carried out cross section type and optimized dimensions and carries out the structure detailed design, make the structure of designing satisfy low order vibration performance and static stiffness performance.Then structure is optimized, turns on one's side after the optimization and analyze and analysis of fatigue, guarantee that motor coach with top-positioned gas cylinder can not take place under the rollover operating mode that gas cylinder destroys and the gas leakage problem that causes and the structural fatigue permanance of car load.Like this, whole method for designing guarantees that designed motor coach with top-positioned gas cylinder top cover satisfies security and the permanance under low order vibration performance, static stiffness performance and the rollover operating mode, and it is the lightest to possess quality.Thereby when guaranteeing designing quality, shorten the construction cycle and improve competitiveness of product.
Topology optimization design
According to the topology optimization design theory, and set up the basic finite element model of topological optimization with reference to the basic model of sample car.Finite element model adopts plate, beam assembled unit, adopts the higher relatively plate unit based on quadrilateral of precision for the top cover that participates in topological optimization, adopt the buckstay unit with top cover and gusset, precedingly enclose, after closed structure link to each other.
In order to make the topological analysis result can satisfy the requirement of body frame strength and stiffness under each operating mode more all sidedly, this topological analysis has carried out considering crooked operating mode, four kinds of unsettled twisting conditions, left and right turning operating mode, damped condition, and the totally 10 kinds of operating modes of rollover operating mode to the right respectively left.
Crooked operating mode, four kinds of unsettled twisting conditions, left and right turning operating mode and damped conditions, the respective nodes place that all load that bus body is born and constraint are mapped to basic structure is applied on the corresponding node in the mode of centre-point load.Vehicle body load comprises: vehicle body deadweight, passenger's quality, power assembly quality, seat quality.
Fig. 2 and Fig. 3 are that the display density value is the top cover superstructure and the understructure figure of 0.28 o'clock topological optimization gained.With a hook at the end among the figure and need arrange the place of rod member when the part of material is architecture advances, and the part that becomes the cavity is the part of material arranged or few material arranged not after optimizing.Roof topological optimization result has several tangible crossbeams, but the crossbeam number lacks than the number of former car body top cover framework beam, and roof topological optimization result does not have tangible longeron, and former body frame top cover has several longerons.Roof topological optimization result has constituted many triangles, and all is rectangle on the former car body top cover skeleton.Can find that by analysis the result of car body top cover topological optimization and former car body top cover skeleton have bigger difference.Distribution of material has all appearred in top cover and the corresponding position of each window pillar as can be seen the figure as a result from topological optimization, instructions window column correspondence position need be provided with roof bow to form the vehicle body closed loop configuration, help the transmission of power like this, help the coordination of skeleton integral body, be not easy to occur the stress concentration phenomenon.
According to above-mentioned topological result, with reference to former state covering for roofs structure and consider the technology realizability, design bi-layer tip cap skeleton structure as shown in Figure 4, Fig. 5～8 are top cover partial structurtes design proposals.The feasibility of scheme also will be checked through further finite element analysis.
Section optimal
Consider the body lightening target, objective function is elected the body quality minimum as.
This bus body skeleton is totally 338 beam element groups, 40 plate unit groups.Consider that part beam element group is that left-right symmetric distributes, and merges into same unit group as design variable with symmetrical part in the optimization.Also having some is support class formation spare, and as battery bracket, fuel battery engines support etc., these part dimensions are less, easily cause irrational sectional dimension to reduce in optimization, so the sectional dimension of these structural members is not as design variable.Also have some structural members, as underframe longeron, roof rai, these structural member sizes are bigger, as make amendment and can bring technology to realize and the cost problem, so these structural members are not also as design variable.Consider above factor, the cross section of having got 210 beams during this optimization is analyzed altogether is a design variable.
The combination tension of restained beam structure is no more than 210MPa in the strength optimization, and the combination compressive stress is no more than-210MPa.Displacement constraint is: a top cover left side/right vertical beam front end amount of deflection is less than 7mm, and a top cover left side/right vertical beam rear end amount of deflection is less than 20mm, before the top cover air-conditioning/the middle cross beam midway deflection is less than 8mm, and top cover air-conditioning rear cross beam midway deflection is less than 10mm; The preceding rigidity loading beam two ends of displacement constraint nodal displacement is less than 4.2mm in the twisting conditions.
According to optimizing the result under four kinds of operating modes of the unsettled bending combination of bench test torsional rigidity, bending, wheelie bending combination and the trailing wheel of the analysis of skeleton global optimization, and by the mode sensitivity analysis, to the sectional dimension of these each parts of body frame comprehensively shown in subordinate list.Dimension synthesis is mainly followed following principle:
(1) at first takes turns optimization result under five kinds of operating modes of unsettled strength optimization based on the optimization of bench test torsional rigidity, bending strength optimization and one.
(2) contrast initial value, by (1) calculate average-size and initial value differ 10% and revert to initial value with interior parts.
(3), will strengthen than the sectional dimension of sensitive compressible members body frame mode according to mode sensitivity analysis result.
(4) optimize and the strength optimization result according to the bench test torsional rigidity, pay close attention to the wherein more parts of size increase, reducing of the sectional dimension of these parts need be prudent.
(5) mode, rigidity, the intensity of model is checked repeatedly behind the pair cross-section modification of dimension, until satisfying every index.
Fig. 9-the 10th, the member of optimizing comprehensive back sectional dimension overstriking and reducing.As seen, parts overstrikings such as four shanks in floor, preceding floor crossmember, floor crossmember, window pillar are more, and preceding door pillar and middle door pillar have also obtained reinforcement.The parts that sectional dimension reduces mainly contain the underframe longeron, and top cover side bar equivalent-load parts illustrate that the intensity and toughness design load of these parts is rich, thereby can make more reasonable structure to its modification.
Table 3.2-1 is the key property contrast of motor bus body frame before and after optimizing.By table as seen, optimize back body frame quality by the 3.367t that optimizes after preceding 3.612t drops to optimization, equivalent loss of weight 0.245t, actual loss of weight 0.131t falls the anharmonic ratio example up to 6.78%.And the intensity after the optimization all meets the demands, and the stress under each operating mode is all less than the limit of elasticity 210MPa of ordinary low-carbon steel; Torsional rigidity is by the 78369Nm/deg that optimizes after preceding 60486Nm/deg brings up to optimization, (62400～76300Nm/deg) is bigger for the relative torsional rigidity scope of passenger vehicle between centers of this value ratio half bearing-type skeleton structure, but consider that finite element analysis employing non-individual body is dispersed increases for the method for limited unit itself will make the rigidity of analytic target, so this calculating gained rigidity is bigger, but still in the reasonable scope.Optimizing the corresponding lower mode characteristic in back also is improved.
Table 3.2-2 is a fundamental performance parameter of optimizing back header.As seen, the quality of optimizing the back header frame assembly is significantly reduced, and intensity, rigidity and lower mode performance all be improved, and satisfies the performance requirement of half bearing-type motor bus.
More than these have illustrated that the top cover method for designing of the motor coach with top-positioned gas cylinder that is proposed in the present patent application has very excellent effect, when guaranteeing performances such as essential rigidity, intensity, mode, can also make the body frame quality minimum of designing, and method therefor is convenient, practical, efficient.The popularization of this method in Automobile Design will greatly improve the Automobile Design quality and shorten the automobile R﹠D cycle.
Body frame performance comparison before and after table 3.2-1 optimizes
Roof frame assembly performance contrast before and after table 3.2-2 optimizes
Consider the rollover analysis that gas cylinder leaks
In the analysis of rollover collision simulation each assembly of vehicle body is all adopted the modeling of plate unit, propons, back axle and tire also adopt the modeling of plate unit, have only the anti-space frame of invading of living space ladder-shaped frame and top cover hydrogen pipeline to adopt the beam element modeling.
Set up ladder-shaped frame with beam element and replace distortion rule, in order to simulation passenger living space.For guaranteeing that distortion rule do not have relative motion with respect to floor in the rollover process, four nodes and the body transom of ladder-shaped frame is rigidly connected, shown in Fig. 3 .3-2.
For investigating the security in the rollover collision of top cover gas cylinder pipeline and gas cylinder, geometric data according to actual measurement gas cylinder intake line, set up the anti-space of invading of top cover gas cylinder pipeline, anti-high-low limit point of invading space frame is rigidly connected with corresponding roof rai, shown in Fig. 3 .3-3.
The rollover collision is reorganized and outfit at car load and is carried out simulation analysis under the load situation.During analyzing, the rollover collision simulation except that considering the vehicle body sole mass, also to consider quality load such as vehicle body power system, air-conditioning, heating radiator simultaneously.To vehicle body quality load such as hydrogen bottle, hydrogen bottle rack, air-conditioning, heating radiator, fuel battery engines, lithium battery group, accumulator, electric machine controller and motor, speed reduction unit, DC/DC transducers, simulate with mass unit; According to the requirement of ECE R66, to consider the quality load of driver and pilot set simultaneously, this quality load also is to simulate with mass unit.
For the quantitative test body distortion, make things convenient for simultaneously passenger's living space to invade the calculating of coefficient again, get the left side that has a par height with living space framework limes superiors point and enclose point on the column as measuring point, from rollover collision simulation analysis result, obtain these measuring points to the variable in distance-time diagram of corresponding living space limes superiors point (because the not distortion in whole rollover crash analysis of living space framework, the variable in distance that measuring point arrives corresponding living space limes superiors point is the deflection of measuring point just).Each measuring point deflection sees Table 3.3-1.
Column measuring point deflection is enclosed in the left side in the table 3.3-1 rollover collision process
| The measurement point position | Maximum deformation quantity (mm) | Collision finishes deflection (mm) |
| The measurement point position | Maximum deformation quantity (mm) | Collision finishes deflection (mm) |
| The 2nd column is enclosed in the left side | ??214 | ??200 |
| The 3rd column is enclosed in the left side | ??209 | ??207 |
| The 4th column is enclosed in the left side | ??198 | ??197 |
| The 5th column is enclosed in the left side | ??182 | ??180 |
| The 6th column is enclosed in the left side | ??192 | ??192 |
Concern sequential chart according to body distortion and living space position, can visually see in whole rollover process, the ladder-shaped frame of definition living space remains intact, both not had foreign object invades, also do not protrude into beyond the vehicle body, as seen this car satisfies the regulation requirement of GB/T17578-1998 passenger vehicle superstructure intensity.
Enclose each column distortion situation in order further quantitatively to understand the left side, introduce column and invade coefficient as measurement index.Enclose the rate of change of spacing by measuring living space high-low limit point respectively with the left side, be out of shape potential threat to determine column, and then can estimate the crashproof ability of each column living space.Definition U is that column is invaded coefficient
In the formula: d
OriThe primary leading that enclose in living space limit point and left side before the distortion, d
DefThe spacing that enclose in distortion back living space limit point and left side.
When analyzing whole distortion by this car rollover collision simulation program process as can be seen, the gas cylinder cover is not invaded in the anti-intrusion space in the rollover process.Now according to Calculation results, respectively with the security of hydrogen pipeline in the gap quantitative description rollover process of high-low limit point and gas cylinder cover.
Compare with traditional motor bus, top-positioned gas cylinder bi-layer tip cap motor bus weight increases, and height of C.G. increases, thereby such motor bus is easier turns on one's side, and rollover danger is bigger.Be necessary the top-positioned gas cylinder bi-layer tip cap motor bus simulation analysis of turning on one's side, and this analysis helps motor bus is improved design.
The column introduced in the literary composition is invaded the margin of safety of passenger's living space in the quantitative evaluation motor bus rollover collision that coefficient can be intuitively concrete; But the anti-intrusion of top cover gas cylinder pipeline zone and the gap quantitative evaluation gas cylinder pipeline of gas cylinder cover and the security of gas cylinder.
To this motor bus impact simulation of turning on one's side, analog result shows that this passenger vehicle living space in the rollover collision process is not invaded according to ECER66, and rollover can not cause the gas cylinder pipeline leakage.In a word, this car rollover performance meets the demands.
Analysis of fatigue
The analysis of fatigue finite element model is selected the plate unit for use.The passenger calculates with everyone 65kg on the vehicle body, part quality such as quality, gas cylinder, fuel battery engines and the power system relevant device of people and seat, air-conditioning are added to relevant position on the vehicle body by the mode of lumped mass unit, in the vehicle operating process, any lumped mass of carrying on the vehicle body all can produce significant effects to integrally-built dynamic response.The big more influence of lumped mass is remarkable more.Therefore, in carrying out body structure transient state dynamic response, must consider carefully by the caused dynamic effect of lumped mass.For better load condition that is virtually reality like reality, the some of them mass unit affacts on the pairing node in actual installation position by multi-point constraint unit rbe3.The vertical drive of vehicle body causes because the fatigure failure of vehicle body is mainly passed to by suspension by road roughness, so the position that vehicle body is connected with suspension is reduced to 6 suspension point of excitation, vehicle body is fully loaded with quality 15.255t.
A large amount of experimental measurements show that road roughness is to have zero-mean, ergodic steady Gauss stochastic process.In engineering reality, describe the statistical property on road surface usually with power spectrum density, and the power spectrum density of road roughness can be used the following formula match:
In the formula, n is a spatial frequency, and it is the inverse of wavelength, represent to comprise number wave period in every meter length, and n＞0; n
0Be reference spatial frequency, n
0=0.1m
-1, G
x(n
0) be with reference to spatial frequency n
0Under the road surface power spectrum density, be called the road roughness coefficient, data depend on the pavement grade of highway, unit: m
2/ m
-1W is a frequency index, is the frequency of oblique line on the log-log coordinate, and the frequency structure of its decision road surface power spectrum density is got w=2.Automobile ride random input running test method GB/T4970-1996 regulation: test condition is a bituminous road, and its pavement grade should meet the B level road surface of GB 7031 regulations; And municipal highway generally all is a bituminous pavement, and the fatigue of automobile is subjected to the road surface arbitrary excitation by automobile and causes, so select B level road surface in analyzing.Its road roughness coefficient G
x(n
0) geometrical mean be 64/ (10-6m3), the city bus speed of a motor vehicle commonly used be 50～80 kms/hour, select in the analysis speed of a motor vehicle be 60 kms/hour, utilize the matlab programming to calculate the displacement time history on B level road surface as Fig. 3 .4-1 (unit: mm): (only having intercepted the displacement time diagram of preceding 20s time among the figure).
In order fully to reflect the characteristic on B level road surface, the sampling time of choosing is 2000s, and sample frequency is 167Hz, and the road surface sample of this sampling enough reflects the characteristic on B level road surface.
Import as the external world with road excitation, to tire, suspension, the hard and soft property multi-body system that vehicle body is formed is carried out dynamic simulation, adopt the SFORCE power element among the ADAMS to set up tire model, adopt the acting force between IMPACT impulsive force functional simulation tire and the ground in the modeling.Hard and soft many phantoms of the property type that includes tire, suspension and body frame composition is carried out road traveling emulation, extract the time history of vehicle body and suspension tie point place power by simulation result, the vertical drive of vehicle body causes because the fatigure failure of vehicle body is mainly passed to by suspension by road roughness, so the power that when we analyze suspension is affacted vehicle body is simplified, only extract spring and vibroshock and act on z on the vehicle body, and it is added and be used as the pumping signal that acts on the body mount point to the time history of power.
Concerning the car load auto model, the road surface input should consider that the coherence of left and right sides vehicle and the time of front and back vehicle prolong chi, the vertical drive of vehicle body causes because the fatigure failure of vehicle body is mainly passed to by suspension by road roughness, so only consider the effect of vertical load in analyzing, do not consider the influence of side direction, the road excitation of left and right wheels is thought identical, and the suffered road excitation of trailing wheel can be thought the time delay of front-wheel institute excited target, time delay:
L is the axletree distance, and v is the speed of a motor vehicle.The B level road excitation that generates is acted on tire model, again in conjunction with suspension, hard and soft many phantoms of property type that vehicle body is formed (vehicle body adopts the rigid body simulation) carries out road traveling emulation, extract the time history of the power of spring and the vertical direction of damper action on vehicle body by simulation result, and it is added and as the pumping signal that acts on the body mount point.
Because the air spring about front suspension communicates, so the power that its air spring outputs on the vehicle body is the same; The front and back air spring of same rear suspension communicates, so the power that its air spring outputs on the vehicle body is the same.But because it is inequality to also have damper, the effect of its damping force to cause being input to the power of the suspension point on the vehicle body in the suspension.The PSD figure's of the power of suspension point is different before and after the rear suspension of Fig. 3 .4-9 and Fig. 3 .4-14 left side, can obviously analyze it and not be both because the effect of damper.
The tired result of calculation of this motor coach with top-positioned gas cylinder body frame, the maximum cycle of dangerous position is 7.43E7 time, amounting to into the enforcement distance is 123.86 ten thousand kilometers.Roof bow and longeron junction, roof bow corner mainly appear in its tired dangerous unit.In order to estimate the fatigue lifetime to this motor coach with top-positioned gas cylinder, to also analyzing the fatigue lifetime of the reference sample car of individual layer top cover, shown in Fig. 3 .4-9, the maximum cycle of dangerous position is 4.34E6 time, and amounting to into the enforcement distance is 83.2 ten thousand kilometers.Its tired dangerous unit mainly appears at roof bow corner.Table 3.4-1 has listed contrast fatigue lifetime of these two kinds of vehicles.From the table data as seen, the bi-layer tip cap motor bus of designing according to the method for designing that the application proposed has more superior fatigue durability.
Table 3.4-1 bi-layer tip cap motor bus is estimated fatigue lifetime
The maximum cycle of the dangerous position of the bi-layer tip cap motor bus of designing according to the method for designing that the application proposed is 7.43E7 time, and amounting to into the enforcement distance is 123.86 ten thousand kilometers.And the maximum cycle of the dangerous position of the reference sample car of individual layer top cover is 4.34E6 time, and amounting to into the enforcement distance is 83.2 ten thousand kilometers.The bi-layer tip cap motor bus that explanation is designed according to the method for designing that the application proposed has more superior fatigue durability.
Motor coach with top-positioned gas cylinder construction design method based on topological optimization, section optimal, roll stability analysis and analysis of fatigue provided by the present invention, the comparative analysis that reaches ripe vehicle by finite element analysis shows, by the top-positioned gas cylinder bi-layer tip cap motor bus main body framework structure of method for designing of the present invention design not only satisfy static stiffness, lower mode characteristic, roll stability and the fatigue durability requirement, and than the individual layer top cover passenger vehicle of classic method design have light, the most superior roll stability of quality and fatigue durability.The popularization of this method in the method for designing of similar motor coach with top-positioned gas cylinder top cover will greatly improve designing quality and shorten the design cycle.
Claims (6)
1. definite method that is used for dual-layer top cover of motor coach with top-positioned gas cylinder, comprise: topological optimization, initial configuration design, section optimal, roll stability analysis and analysis of fatigue, it is characterized in that: according to designing requirement, on the basis that comprises conditions such as load-bearing capacity, profile, power layout, adopt topology optimization design, obtain the preliminary space structure of top cover, then this preliminary space structure is carried out section optimal and carry out architecture advances design, make the structure after the improvement satisfy low order vibration performance and static stiffness performance; Turn on one's side and analyze and analysis of fatigue improving structure again, guarantee that motor coach with top-positioned gas cylinder can not take place under the rollover operating mode that gas cylinder destroys and the gas leakage problem that causes and the structural fatigue permanance of car load; Guarantee that designed motor coach with top-positioned gas cylinder top cover satisfies security and the permanance under low order vibration performance, static stiffness performance, the rollover operating mode.
2. method according to claim 1, it is characterized in that: in the topology optimization design step, finite element model adopts plate, beam assembled unit, adopt higher relatively the plate unit of precision for the top cover that participates in topological optimization based on quadrilateral, adopt rigid element with top cover and gusset, precedingly enclose, afterwards closed structure links to each other;
In order to make the topological analysis result can satisfy the requirement of body frame strength and stiffness under each operating mode more all sidedly, this topological analysis carried out respectively considering crooked operating mode, four kinds of unsettled twisting conditions, left and right turning operating mode, damped condition, left with the rollover operating mode on the right side totally 10 kinds of operating modes;
Crooked operating mode, four kinds of unsettled twisting conditions, left and right turning operating mode and damped conditions, the respective nodes place that all load that bus body is born and constraint are mapped to basic structure is applied on the corresponding node in the mode of centre-point load; Vehicle body load comprises: vehicle body deadweight, passenger's quality, power assembly quality, seat quality.
3. method according to claim 1 is characterized in that: in the section optimal step, consider the body lightening target, objective function is elected the body quality minimum as.
4. method according to claim 1 is characterized in that: in the section optimal step, dimension synthesis is followed following principle:
(1) at first takes turns optimization result under five kinds of operating modes of unsettled strength optimization based on the optimization of bench test torsional rigidity, bending strength optimization and one;
(2) contrast initial value, by (1) calculate average-size and initial value differ 10% and revert to initial value with interior parts;
(3), will strengthen than the sectional dimension of sensitive compressible members body frame mode according to mode sensitivity analysis result;
(4) optimize and the strength optimization result according to the bench test torsional rigidity, pay close attention to the wherein more parts of size increase, reducing of the sectional dimension of these parts need be prudent;
(5) mode, rigidity, the intensity of model is checked repeatedly behind the pair cross-section modification of dimension, until satisfying every index.
5. method according to claim 1, it is characterized in that: in the analysis of rollover collision simulation, each assembly of vehicle body is all adopted the modeling of plate unit, propons, back axle and tire also adopt the modeling of plate unit, have only the anti-space frame of invading of living space ladder-shaped frame and top cover hydrogen pipeline to adopt the beam element modeling;
Set up ladder-shaped frame with beam element and replace distortion rule, in order to simulation passenger living space; For guaranteeing that distortion rule do not have relative motion with respect to floor in the rollover process, four nodes and the body transom of ladder-shaped frame is rigidly connected;
For investigating the security in the rollover collision of top cover gas cylinder pipeline and gas cylinder, according to the geometric data of actual measurement gas cylinder intake line, set up the anti-space of invading of top cover gas cylinder pipeline, anti-high-low limit point of invading space frame is rigidly connected with corresponding roof rai;
The rollover collision is reorganized and outfit at car load and is carried out simulation analysis under the load situation.
6. method according to claim 1 is characterized in that: in the analysis of fatigue step, the analysis of fatigue finite element model is selected the plate unit for use; Part quality such as quality, gas cylinder, fuel battery engines and the power system relevant device of people and seat, air-conditioning are added to relevant position on the vehicle body by the mode of mass unit; In carrying out body structure transient state dynamic response, must consider carefully by the caused dynamic effect of lumped mass; For better load condition that is virtually reality like reality, the some of them mass unit affacts on the pairing node in actual installation position by multi-point constraint unit rbe3; The position that vehicle body is connected with suspension is reduced to 6 suspension point of excitation;
Import as the external world with road excitation, to tire, suspension, the hard and soft property multi-body system that vehicle body is formed is carried out dynamic simulation, adopt the SFORCE power element among the ADAMS to set up tire model, adopt the acting force between IMPACT impulsive force functional simulation tire and the ground in the modeling; Hard and soft many phantoms of the property type that includes tire, suspension and body frame composition is carried out road traveling emulation, extract the time history of vehicle body and suspension tie point place power by simulation result; The power that during analysis suspension is affacted vehicle body is simplified, and only extracts spring and vibroshock and acts on z on the vehicle body to the time history of power, and it is added and be used as the pumping signal that acts on the body mount point;
Concerning the car load auto model, the road surface input should be considered the coherence of left and right sides vehicle and the time delay of front and back vehicle, only consider the effect of vertical load in the analysis, do not consider the influence of side direction, the road excitation of left and right wheels is thought identical, and the suffered road excitation of trailing wheel can be thought the time delay of front-wheel institute excited target.
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