CN108038308A - A kind of construction design method of aluminium alloy compression casting damping tower - Google Patents
A kind of construction design method of aluminium alloy compression casting damping tower Download PDFInfo
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- 238000013016 damping Methods 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims abstract description 28
- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 20
- 238000005266 casting Methods 0.000 title abstract 2
- 230000006835 compression Effects 0.000 title abstract 2
- 238000007906 compression Methods 0.000 title abstract 2
- 238000010276 construction Methods 0.000 title abstract 2
- 238000005457 optimization Methods 0.000 claims abstract description 66
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 28
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 22
- 239000010959 steel Substances 0.000 claims abstract description 22
- 238000009826 distribution Methods 0.000 claims abstract description 8
- 238000004458 analytical method Methods 0.000 claims abstract description 4
- 238000006073 displacement reaction Methods 0.000 claims description 21
- 238000004512 die casting Methods 0.000 claims description 19
- 230000035939 shock Effects 0.000 claims description 12
- 239000011159 matrix material Substances 0.000 claims description 9
- 238000010521 absorption reaction Methods 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 238000013178 mathematical model Methods 0.000 claims description 6
- 239000002344 surface layer Substances 0.000 claims description 2
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- 238000005516 engineering process Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 239000006096 absorbing agent Substances 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000003351 stiffener Substances 0.000 description 1
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- G06F30/00—Computer-aided design [CAD]
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Abstract
The present invention proposes a kind of construction design method of aluminium alloy compression casting damping tower, according to the analysis of raw steel damping tower structure and experimental results, extracts correlated performance data and building topology optimization space；Then the division of region and Non-design region is designed to topological optimization space；To design section, the rational position for determining reinforcing rib by topological optimization is distributed；According to the reinforcing rib position distribution obtained to topological optimization result, the damping tower model with reinforced bag sand well is re-established, passes through the dimensionally-optimised optimal thickness for being further strengthened muscle；Finally the damping tower model after dimensionally-optimised is checked, it is ensured that designed structure meets performance demand.Present invention reduces the design cycle, design efficiency, structure lightened positive effect are improved, comprehensive performance is significantly improved.
Description
Technical Field
The invention belongs to the technical field of bending and forming of a plate bending machine, and particularly relates to a structural design method of an aluminum alloy die-casting damping tower.
Background
The rapid development of the automobile industry brings convenience to people's trip and also brings pollution to the environment, energy conservation and emission reduction become difficult problems of the development of the automobile industry, and the light weight technology is the best mode for solving the problem.
Traditional part design mainly relies on experience and existing relevant structure, need to combine actual production trial and error, and design cycle is long, and is with high costs. With the development of finite element technology, part design has formed a complete set of theoretical systems: topology optimization, size optimization, shape optimization and appearance optimization. Topology optimization has become an effective way of conceptual design of parts, and the form of a structure is determined in preliminary design; the appearance optimization mainly aims at the design of stamping part reinforcing ribs; the size optimization and the shape optimization carry out fine adjustment on the local size and shape in the detailed design stage of the part. The optimization method can be selected or combined according to the specific form of the part. The finite element optimization scheme greatly shortens the design period, and improves the design efficiency while ensuring the reliability of the structural design.
The shock absorption tower is one of important parts of an automobile and is a key part for connecting a shock absorber and a front automobile body, and impact load caused by uneven ground in the running process of the automobile is transmitted to the shock absorption tower through the attenuation of the shock absorber and then dispersed to the front automobile body. The automobile shock absorption tower plays an important role in improving the running stability of the automobile and the NVH performance of the whole automobile. At present, a damping tower mainly adopts a welding process of a plurality of steel plate stamping parts, the manufacturing process is complex, the production cost is high, the mounting and dismounting efficiency is low, and the temperature difference near welding spots in the welding process easily causes local stress concentration to influence the overall assembly precision of the structure. The aluminum alloy replaces steel parts to become a trend of light vehicle bodies, and the development of aluminum alloy structural parts suitable for die casting technology mainly depends on experience, and meanwhile, repeated tests have low design efficiency and poor light weight effect, so that a structural design method for efficiently replacing the steel damping tower aluminum alloy die casting is very needed.
Disclosure of Invention
The invention aims to solve the technical problems and provides a structural design method of an aluminum alloy die-casting damping tower, which shortens the design period of an aluminum alloy die-casting piece and improves the light weight effect.
The technical scheme adopted by the invention for solving the technical problems is as follows: the structural design method of the aluminum alloy die-casting damping tower is characterized by comprising the following steps of:
s1) extracting a first-order model of the steel damping tower from the numerical analysis and experimental test results of the whole vehicle model
The state, the stress boundary condition under different extreme working states and the maximum displacement of the corresponding characteristic point under different extreme working states;
s2) designing a topological optimization space which comprises the original structure geometric shape and does not generate assembly interference with other parts of the front vehicle body according to the steel damping tower structure, and dividing a design area and a non-design area of the topological optimization space: the surface layer is set to be a non-optimized area with a certain thickness and used as a basic structure of the damping tower, and the rest part of the inner side is a design area and used as an optimized area of the distribution position of the reinforcing ribs;
s3) taking the maximum displacement of the corresponding characteristic points in different extreme working states extracted in the step S1) as constraint conditions, taking the unit density of the design area in the step S2) as an optimized design variable, minimizing the overall quality as an optimized design target, and determining the position of the reinforcing rib according to a topological optimization result;
s4) taking the maximum displacement at the corresponding characteristic points under different extreme working states extracted in the step S1) as constraint conditions, modeling again according to the position of the reinforcing rib obtained in the step S3), taking the thickness of the reinforcing rib as an optimal design variable, minimizing the overall quality as an optimal design target, and determining the width of the reinforcing rib according to a size optimization result;
and S5) checking the structure obtained by topology optimization and size optimization to ensure that the designed aluminum alloy die-casting damping tower is suitable for an aluminum alloy die-casting process, and the structure meets the maximum displacement requirement of the corresponding characteristic points under different extreme working states extracted in the step S1).
According to the scheme, the step S3) comprises the following steps: according to the process requirement, manufacturing constraints of drawing or extruding are defined for a design area, and the topological optimization mathematical model can be expressed as follows:
an objective function: w (rho) i )
Constraint conditions are as follows: 1) 0<ρ min ≤ρ i ≤1；
2)
Wherein W is an objective function of the topological optimization model and represents the overall quality of the structure, rho i Is a design variable of the optimization model; rho i Denotes the relative cell density, p, of the ith cell min To its minimum value; k represents a global stiffness matrix that is,is the loading condition of the mth loading point under the nth working condition,andrespectively representing the topological optimization space and the displacement of the mth loading point of the original steel product under the nth working condition.
According to the above scheme, in the step S4), design variables of different reinforcing ribs may be set as associated or non-associated design variables, the design variables may be defined as continuous or discontinuous according to an actual process, and the mathematical model for size optimization may be expressed as:
an objective function: c (T) j )
Constraint conditions are as follows: 1)
2)f 1 ≥F 1 ；
3)
Wherein C is an objective function of the size optimization model and represents the overall quality of the structure, and T j Is a design variable of the size optimization model; t is a unit of j Represents the j-th size variable and is,andrespectively represent the upper and lower limit values; f. of 1 Is a structure of a first order modal frequency, F 1 The lower limit value is the primary modal frequency of the original steel product; k represents a global stiffness matrix and K represents a global stiffness matrix,is the loading condition of the mth loading point under the nth working condition,andrespectively representing the topological optimization space and the displacement of the mth loading point of the original steel product under the nth working condition.
The invention has the beneficial effects that: a structural design method of an aluminum alloy die-casting damping tower solves the difficult problem of determining the position and the size of a reinforcing rib of a thin-wall part, enables the distribution of materials to be more reasonable, improves the utilization rate of the materials, reduces the experience requirement of designers, and improves the design efficiency.
Drawings
FIG. 1 is a schematic illustration of a shock tower according to one embodiment of the present invention after installation;
FIG. 2 is a schematic diagram of a topological optimization space designed according to the external shape structure of a steel shock absorption tower according to an embodiment of the present invention;
fig. 3 is a schematic structural view of a thin-walled die-cast shock tower with stiffeners, according to an embodiment of the invention.
Wherein: 1. the damping device comprises a damping tower, a front vehicle body, a flange, a reinforcing rib, a shell, a left loading point, a middle loading point and a right loading point, wherein the front vehicle body is 2, the flange is 3, the reinforcing rib is 4, the shell is 5, the left loading point is 6, the middle loading point is 7, and the right loading point is 8.
Detailed Description
For a better understanding of the present invention, reference is made to the following description taken in conjunction with the accompanying drawings and examples.
A structural design method of an aluminum alloy die-casting damping tower comprises the following steps:
(1) According to the installation model of the damping tower 1 in the figure 1, constraint and load are simplified, the original steel damping tower is subjected to stress analysis under different limit working conditions, and the first-order mode of the original steel damping tower, stress boundary conditions under different limit working conditions and the maximum displacement of corresponding characteristic points under different limit working conditions are extracted by combining experimental test results. The positions of the loading points are shown as a left loading point 6, a middle loading point 7 and a right loading point 8 in the figure 1.
(2) According to the structural form of the shock absorption tower in the figure 1 and the assembling position relation with other parts of the front vehicle body 2, a topological optimization space as shown in the figure 2 is designed, and the overall thickness of a model is about 10mm. The topological optimization space does not interfere with other assembly parts of the front automobile body, and the original steel shock absorption tower structure is contained in the optimization space geometric body. The method comprises the following steps of dividing a design area and a non-design area in the thickness direction of a topological space, wherein the upper layer (a shell part) is a non-design area and is used as a basic structure of a part, the thickness of the part is about 3mm, and the lower layer (a reinforcing rib arrangement area) is a design area so as to optimize the distribution position of the reinforcing ribs and be about 7mm.
(3) Taking the maximum displacement of the corresponding characteristic points extracted in the step (1) under different extreme working states as constraint conditions, taking the unit density of the design area in the step (2) as an optimization design variable, minimizing the whole quality as an optimization design target, performing topological optimization design based on an SIMP (simple in process map) method on the inner layer design interval, and applying vertically downward drawing constraint by taking the top disc-shaped mounting surface as a reference, such as a black arrow in the figure 2. And determining the position of the reinforcing rib according to a topology optimization result to obtain a continuous mesh structure with the minimum structure quality. The displacement (rigidity) requirements and the integral first-order modal requirements of the part of the damping tower under different working conditions are shown in table 1, the total number of the working conditions is 5, and each working condition has 3 loading points. The topological optimization mathematical model is as follows:
an objective function: w (rho) i )
Constraint conditions are as follows: 1) 0<ρ min ≤ρ i ≤1；
2)
Wherein W is an objective function of the topological optimization model and represents the integral quality of the structure, rho i Is a design variable of the optimization model; ρ is a unit of a gradient i Denotes the relative cell density, p, of the ith cell min To its minimum value; k denotes the global stiffness matrix, P n For the load condition in the n-th operating condition,indicating the displacement of the mth loading point under the nth condition,is the displacement of the mth loading point of the original steel product under the nth working condition.
(4) The optimization result of the design interval obtained in the step (3) is understood as the distribution position of the reinforcing ribs, the structure is modeled again, the distribution position of the reinforcing ribs is as shown in figure 3, the maximum displacement at the corresponding characteristic points under different extreme working states extracted in the step (1) is taken as a constraint condition, the thickness of the reinforcing ribs is taken as an optimization design variable, the overall quality is minimized as an optimization design target,and obtaining a reasonable value of the thickness of the reinforcing rib when the quality is minimum through size optimization. The thickness variable of the reinforcing ribs is distributed according to positions and is designed as T 1 -T 8 The number of the design variables is 8, each variable is set to be discontinuous according to die casting technology and die machining and manufacturing requirements, increment is 0.1mm, and the optimization range of each design variable and the optimized optimal thickness value are listed in table 2. The mathematical model for size optimization is as follows:
an objective function: c (T) j )
Constraint conditions are as follows: 1)
2)f 1 ≥F 1 ；
3)
Wherein C is an objective function of the size optimization model and represents the overall quality of the structure, T j Is a design variable of the size optimization model; t is a unit of j Represents the j-th size variable and is,andrespectively represent the upper and lower limit values; f. of 1 For the structure of a first-order modal frequency, F 1 The lower limit value is the first-order modal frequency of the original steel product; k denotes the global stiffness matrix, P n For the load condition in the n-th operating condition,indicating the displacement of the mth loading point under the nth condition,is the displacement of the mth loading point of the original steel product under the nth working condition.
(5) And (3) checking the structure obtained by topology optimization and size optimization, and ensuring that the designed damping tower structure suitable for the aluminum alloy die-casting process meets all performance requirements extracted in the step (1), including the requirements of 15 displacement (rigidity) of 3 loading points under 5 working conditions and the requirement of an integral first-order mode.
The thickness of the vacuum die-casting damping tower obtained by the method for designing the thin-wall structure with the reinforcing ribs is about 3mm. The mass of the damping tower before and after optimization is respectively 7.1Kg and 3.9Kg, and the mass of the newly designed damping tower is reduced by 45 percent while the structure static strength and the static rigidity meet the original design requirements. Through the topological optimization and the size optimization, the material distribution is more reasonable, the material utilization rate is improved, and the lightweight effect is obvious. The design method for the aluminum alloy die casting structure replacing the steel shock absorption tower can effectively solve the problem of determining the position and the size of the reinforcing rib of the thin-wall part, reduces the experience requirements on designers, shortens the design period and improves the design efficiency.
TABLE 1
TABLE 2
Claims (3)
1. The structural design method of the aluminum alloy die-casting damping tower is characterized by comprising the following steps of:
s1) extracting a first-order mode of a steel damping tower, stress boundary conditions under different extreme working states and maximum displacement of corresponding characteristic points under different extreme working states from a numerical analysis and experimental test result of the whole vehicle model;
s2) according to the steel damping tower structure, a topological optimization space which comprises the original structure geometric shape and does not generate assembly interference with other parts of the front vehicle body is designed, and a design area and a non-design area are divided for the topological optimization space: the surface layer is set to be a non-optimized area with a certain thickness and used as a basic structure of the damping tower, and the rest part of the inner side is a design area and used as an optimized area of the distribution position of the reinforcing ribs;
s3) taking the maximum displacement of the corresponding characteristic points in different extreme working states extracted in the step S1) as constraint conditions, taking the unit density of the design area in the step S2) as an optimized design variable, minimizing the overall quality as an optimized design target, and determining the position of the reinforcing rib according to a topological optimization result;
s4) taking the maximum displacement of the corresponding characteristic points in different extreme working states extracted in the step S1) as constraint conditions, re-modeling according to the position of the reinforcing rib obtained in the step S3), taking the thickness of the reinforcing rib as an optimized design variable, minimizing the overall quality as an optimized design target, and determining the width of the reinforcing rib according to a size optimization result;
and S5) checking the structure obtained by topology optimization and size optimization to ensure that the designed aluminum alloy die-casting damping tower is suitable for an aluminum alloy die-casting process, and the structure meets the maximum displacement requirement of the corresponding characteristic points under different extreme working states extracted in the step S1).
2. The method as claimed in claim 1, wherein the step S3) comprises the following steps: according to the process requirement, manufacturing constraints of drawing or extruding are defined for a design area, and the topological optimization mathematical model can be expressed as follows:
an objective function: w (rho) i )
Constraint conditions are as follows: 1) 0<ρ min ≤ρ i ≤1；
Wherein W is an objective function of the topological optimization model and represents the overall quality of the structure, rho i Is a design variable of the optimization model; rho i Denotes the relative cell density, p, of the ith cell min To its minimum value;k represents a global stiffness matrix and K represents a global stiffness matrix,is the m load point load condition under the n working condition,andrespectively representing the topological optimization space and the displacement of the mth loading point of the original steel product under the nth working condition.
3. The structural design method of an aluminum alloy die-casting shock absorption tower as claimed in claim 1, wherein the design variables of different reinforcing bars in step S4) can be set as related or unrelated design variables, the design variables can be defined as continuous or discontinuous according to the actual process, and the mathematical model for size optimization can be expressed as:
an objective function: c (T) j )
Constraint conditions are as follows:
2)f 1 ≥F 1 ；
wherein C is an objective function of the size optimization model and represents the overall quality of the structure, and T j Is a design variable of the size optimization model; t is a unit of j Represents the j-th size variable and is,andrespectively represent the upper and lower limit values；f 1 For the structure of a first-order modal frequency, F 1 The lower limit value is the primary modal frequency of the original steel product; k represents a global stiffness matrix and K represents a global stiffness matrix,is the loading condition of the mth loading point under the nth working condition,andand respectively representing the topological optimization space and the displacement of the mth loading point of the original steel product under the nth working condition.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110728084A (en) * | 2019-09-16 | 2020-01-24 | 中国第一汽车股份有限公司 | Forward design method for hollow thin-wall aluminum casting |
| CN110990945A (en) * | 2019-11-15 | 2020-04-10 | 武汉理工大学 | Design method for bionic structure of automobile roof reinforcing rib |
| CN116738740A (en) * | 2023-06-20 | 2023-09-12 | 小米汽车科技有限公司 | Structure optimization method and device for large die casting |
| CN116776693A (en) * | 2023-06-26 | 2023-09-19 | 小米汽车科技有限公司 | Shock absorber optimal design method and device, electronic equipment and storage medium |
-
2017
- 2017-12-11 CN CN201711310020.9A patent/CN108038308A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| HUAJIE MAO等: "Lightweight design of a shock tower based on topology and size optimization", 《7TH INTERNATIONAL CONFERENCE ON ADVANCED DESIGN AND MANUFACTURING ENGINEERING (ICADME 2017)，ADVANCES IN ENGINEERING RESEARCH》 * |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110728084A (en) * | 2019-09-16 | 2020-01-24 | 中国第一汽车股份有限公司 | Forward design method for hollow thin-wall aluminum casting |
| CN110728084B (en) * | 2019-09-16 | 2023-03-10 | 中国第一汽车股份有限公司 | Forward design method for hollow thin-wall aluminum casting |
| CN110990945A (en) * | 2019-11-15 | 2020-04-10 | 武汉理工大学 | Design method for bionic structure of automobile roof reinforcing rib |
| CN110990945B (en) * | 2019-11-15 | 2022-05-06 | 武汉理工大学 | Design method for bionic structure of automobile roof reinforcing rib |
| CN116738740A (en) * | 2023-06-20 | 2023-09-12 | 小米汽车科技有限公司 | Structure optimization method and device for large die casting |
| CN116738740B (en) * | 2023-06-20 | 2024-04-02 | 小米汽车科技有限公司 | Structure optimization method and device for large die casting |
| CN116776693A (en) * | 2023-06-26 | 2023-09-19 | 小米汽车科技有限公司 | Shock absorber optimal design method and device, electronic equipment and storage medium |
| CN116776693B (en) * | 2023-06-26 | 2024-03-19 | 小米汽车科技有限公司 | Shock absorber optimal design method and device, electronic equipment and storage medium |
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Application publication date: 20180515 |