【機械類畢業(yè)論文中英文對照文獻(xiàn)翻譯】基于有限元分析的單梁橋式起重機優(yōu)化設(shè)計
【機械類畢業(yè)論文中英文對照文獻(xiàn)翻譯】基于有限元分析的單梁橋式起重機優(yōu)化設(shè)計,機械類畢業(yè)論文中英文對照文獻(xiàn)翻譯,機械類,畢業(yè)論文,中英文,對照,對比,比照,文獻(xiàn),翻譯,基于,有限元分析,橋式起重機,優(yōu)化,設(shè)計
Based On The Finite Element Analysis Of Single Girder Crane Optimization Design
Summary
Use ANSYS9.0 analysis single girder crane steel structure of the mechanical characteristics, and combining analysis results luo practical experience puts forward corresponding structure optimization scheme, the correctness and rationality verified, and optimal design for the similar product reference.
Key word: bridge cranes; Steel structure; Optimization design; FEM
It is used widely in machine manufacture, metallurgy, steel, wharf bridge crane with China accounts for about 40% of the crane. The original crane design method for more traditional design methods, design the efficiency is low, the design crane safety factor is big, consume more than raw material, structure is not rational. To be on the steel structure optimization design.
Usually the optimization design is using mathematical programming method, mechanical engineering design problems will be transformed by correspondence and target constraint conditions description limit optimization problem. The method for solving the problem of the optimization of the typical can get better optimization results, but for engineering practice often appear multiple targets, the constraint conditions optimization problem there is difficult to establish mathematical model and calculation complex, difficult to application.
In view of this, this paper using finite element analysis software for possible structure design scheme of rapid virtual test, and through the analysis of the results of the tests of virtual FEM, and makes the corresponding structure optimization. With LX type single girder crane Lord LiangGang structure as an example, the use of ANSYS simulation in the worst condition of the stress distribution and deformation condition, the author puts forward the optimal scheme and test.
1. The LX type 5 t electric suspension single girder crane steel structure characteristics
LX type 5 t electric suspension single girder crane girder and two by the beam, the electric hoist, during operation mechanism, and electric equipment and other major parts. Wheel group hangs upside down in the workshop the H of rail operation. The central beam I32a girder by paper box beam and welded; Both ends of I32a range by the cantilever and channel steel [28 a welded; the two root channel steel beam by [18 and welded steel box girder, through the beam two lug realization and the connection of the girders, as shown in figure 1 .
2. Finite element modeling and analysis method
2.1 units of the selection and grid partition
LX type 5 t electric suspension single girder crane steel in the range, channel steel box girder and the main dimensions are of its thickness 10 times above, the selected shell element (shall 63) in the bridge cranes finite element analysis [1]. In addition, choose shell element model optimization for modification.
2.2 determined the bad working environment
The related theory shows that: the small car in the midspan and brake, cart rail connection and brake ways; The car is located in limit position of the cantilever beam and brake, cart rail connection and ways for the worst deflection happened in 2 working [2]. The former used to determine the largest comprehensive stress across the main girder and maximum deflection; The latter are used to determine the main support section at the end of the maximum shear stress.
2.3 sure loading project and constraint mode
The above two kinds of condition and the Lord LiangGang structure characteristics can be sure loading project as is shown in table 1.
Main arms outstretched is simply supported beam model, the vertical and horizontal load, should pin end protection X, Y, Z direction of movement, the other end constraint fulcrum X and Y directions of displacement.
3. Before optimization structure analysis
The above 2 by using ANSYS work conditions after loading solution, the result (see figure 2, figure 3. Figure 2 for the operation condition of the main girder comprehensive stress distribution under a cloud. Examine the stress distribution in the cloud, it is known that the main DiaoZhuangKong lug around regional stress value is higher, and in DiaoZhuangKong face appeared biggest comprehensive stress 171.778 MPa. Central main stress only 48.851 ~ 93.7 MPa. Box beam ends right Angle and acute Angle transition weld seams stress for 117.127 ~ 140.548 MPa. Figure 3 for the deflection of the main girder, the vertical direction maximum displacement 20.766 mm, horizontal direction the maximal displacement of 7.398 mm, the maximal displacement occurred in central main girder.
4 structure optimization scheme
4.1 the basis for the proposed scheme
The above analysis result shows that the single girder crane strength and stiffness reserve enough, this is because the design method of safety with bias, the calculation of the selection the bigger coefficient. Considering the main bearing part is the range, in no full discussion of the circumstances change model smaller hungry must exist range uncertainty. So, this is a main steel beam from the box beam, with a preliminary discussion optimization box beam of steel plate girder thickness of strength and rigidity influence.
4.2 the implementation of the programme
Box girder beams into fluctuation two parts, upside down into the u-shaped box, for 6 mm of thickness is welded steel plate; The lower into the body and the V horizontal clapboard and strengthen the floors, thickness of 5 mm. Now a box beam steel plate thickness decreases 1 mm, observe the analysis results whether meet the intensity and rigidity requirements. Because of this paper have the shell finite element model unit (shell 63) to analyze the box girders so only need to modify the corresponding board thick real constant solution again, can convenient investigation after optimization of mechanical properties of main girder.
4.3 the optimization results analysis
Figure 4 for optimization of main girder after comprehensive stress distribution map displays the show, the largest comprehensive stress for 17.958 MPa, accord with the required strength, the largest comprehensive stress occurs in the main DiaoZhuangKong lug around mining face. Evaluate the comprehensive stress distribution, except the main DiaoZhuangKong lug around the stress of stress concentration in the numerical relatively high, middle girder stress for 58.989 ~ 117.974 MPa. Box beam ends right Angle and acute Angle transition weld seams stress for 154.296 ~ 180.011 MPa, consider commonly after welding of steel plates should be burnish, weld seams round in transition, and finite element analysis model for this round the simplified, cause local stress concentration, where the stress value than the actual value should be high [3].
Figure 5 for the optimization of main girder after deformation, the vertical direction the maximal displacement of 23.095 mm, horizontal direction the maximal displacement of 8.770 mm, accord with the rigidity requirement, the maximal displacement occurred in central main girder. Main girder structure optimization and contrast table 2.
Through the above is known, optimize the thickness of the steel plate handled box girder beams, main girder strength, stiffness has not reduced significantly, and meet the job requirements; The biggest stress occurs location is also no change, main weight was reduced by 8.572%. Better to achieve the purpose of the Lord LiangGang structure optimization.
In addition, from the above finite element analysis results indicated that the comprehensive stress and girder shear stress value higher parts of DiaoZhuangKong lug area nearby box beam ends and steel welding place, although the results show that strength meet the job requirements, but to make the strengthen treatment can effectively improve the life and security. Should be used to improve welding process or welding reinforcing plate shall be reinforced the way.
5 epilogue
Combining with the design personnel design experience and finite element analysis function, through the quick way of virtual test for the optimization of the structure design is relative. And the optimization of the structure of the traditional design method, the comparison, this method have is not mathematical programming concept of optimal solution, but its easy to implement. In addition, this paper example has been put into production, and the result for the similar bridge crane steel structure optimization design provide the beneficial reference.
Reference :
[1] was climbing. The finite element analysis and application [M]. Beijing: tsinghua university press, 2004.
[2] XuGeNing. Lifting transport metal structure design [M]. Beijing: mechanical engineering press, 1995.
[3] YuLanFeng, ZhouZhiAo. Railway crane turntable finite element analysis [J]. Journal of computational mechanics, 2003, 16 (5) : 627-630.
基于有限元分析的單梁橋式起重機優(yōu)化設(shè)計
摘要
利用ANSYS9.0分析單梁橋式起重機鋼結(jié)構(gòu)的力學(xué)特性，并結(jié)合分析結(jié)果咯實際經(jīng)驗提出了相應(yīng)的結(jié)構(gòu)優(yōu)化方案，其正確性和合理性得到驗證，并為同類產(chǎn)品優(yōu)化設(shè)計提供有益參考。
關(guān)鍵字：橋式起重機；鋼結(jié)構(gòu)；優(yōu)化設(shè)計；FEM
目前廣泛應(yīng)用于機械制作、冶金、鋼鐵、碼頭的橋式起重機占具我國起重機的40%左右。原有起重機設(shè)計方法多為傳統(tǒng)的設(shè)計方法，設(shè)計效率低下，設(shè)計起重機安全系數(shù)大、消耗原料多、結(jié)構(gòu)不盡合理。亟待對其鋼結(jié)構(gòu)進(jìn)行優(yōu)化設(shè)計。
通常的優(yōu)化設(shè)計是利用數(shù)學(xué)規(guī)劃的方法，將機械工程的設(shè)計問題轉(zhuǎn)化為由目標(biāo)函授與約束條件描述額度最優(yōu)化問題。該方法對于解決較典型的優(yōu)化問題可以得到較好的優(yōu)化結(jié)果，但對于工程實際中經(jīng)常出現(xiàn)的多目標(biāo)、多約束條件優(yōu)化問題則存在著數(shù)學(xué)模型難以建立及計算復(fù)雜，難于推廣應(yīng)用等問題。
鑒于此，本文利用有限元分析軟件對可能的結(jié)構(gòu)設(shè)計方案快速進(jìn)行虛擬試驗，并通過分析FEM虛擬試驗的結(jié)果，作相應(yīng)的結(jié)構(gòu)優(yōu)化。以LX型單梁橋式起重機主梁鋼結(jié)構(gòu)為例，利用ANSYS模擬其在最惡劣工況下的應(yīng)力分布和變形情況，提出并檢驗了優(yōu)化方案。
一． LX型5t電動懸掛單梁橋式起重機鋼結(jié)構(gòu)特點
LX型5t電動懸掛單梁橋式起重機由主梁和兩條端梁、電動葫蘆、大車運行機構(gòu)、電氣設(shè)備等主要部件組成。車輪組倒掛在車間的H型軌下運行。主梁中部由工字梁I32a和箱型梁焊接而成；兩端懸臂部分則由工字鋼I32a與槽鋼[28a焊接而成；端梁由兩根槽鋼[18與鋼板焊接而成，主梁通過箱型梁兩側(cè)的吊耳實現(xiàn)與端梁的連接，如圖1
所示。
二． 有限元建模和分析方案
2.1單元的選擇與網(wǎng)格劃分
LX型5t電動懸掛單梁橋式起重機鋼結(jié)構(gòu)中的工字鋼、槽鋼和箱型梁的主尺寸均為其厚度的10倍以上，故選定殼單元（shall 63）對該橋式起重機進(jìn)行有限元分析[1]。此外，選用殼單元便于模型的優(yōu)化修改。
2.2確定最惡劣工況
相關(guān)理論表明：小車位于跨中并制動，大車行徑軌道接頭并制動；小車位于懸臂梁極限位置并制動，大車行徑軌道接頭并發(fā)生偏斜為最惡劣的2中工況[2]。前者用于確定主梁跨中最大綜合應(yīng)力和最大撓度；后者用于確定主梁端部支撐截面上的最大剪應(yīng)力。
2.3確定加載方案和約束模式
按以上2種工況和主梁鋼結(jié)構(gòu)特點可確定加載方案如表1所示。
主梁為簡支伸臂梁模型，受垂直和水平方向載荷作用，應(yīng)約束一端支點X,Y,Z方向的位移，約束另一端支點X,Y方向的位移。
三． 優(yōu)化前結(jié)構(gòu)分析
利用ANSYS按以上2中工況加載求解后，其結(jié)果見圖2、圖3。圖2為主梁的工況1下綜合應(yīng)力分布云圖。考察該應(yīng)力分布云圖可知，主梁吊耳吊裝孔附近區(qū)域應(yīng)力值較高，并在吊裝孔工作面出現(xiàn)了最大綜合應(yīng)力171.778MPa。主梁中部應(yīng)力只有48.851~93.7MPa。箱型梁兩端直角和銳角過渡焊縫處應(yīng)力為117.127~140.548MPa。圖3為主梁的變形情況，垂直方向最大位移20.766mm，水平方向最大位移為7.398mm，最大位移發(fā)生在主梁中部。
四．結(jié)構(gòu)優(yōu)化方案
4.1方案提出的依據(jù)
由以上分析結(jié)果可知：該單梁橋式起重機強度和剛度儲備充足，這是因為采用偏安全的設(shè)計方法，計算時選取了較大的系數(shù)。考慮到主梁的承載部分為工字鋼，在沒有充分論證的情況下改換型號較小餓工字鋼存在一定得不確定性。所以，本為從主鋼梁的箱型梁入手，初步探討優(yōu)化箱型梁鋼板厚度對主梁強度和剛度的影響。
4.2方案的實施
主梁箱型梁分為上下兩部分，上部分為倒U形箱體，有厚度為6mm的鋼板焊接而成；下部分為V形箱體、各橫向隔板和加強肋板，厚度為5mm?，F(xiàn)將箱型梁鋼板厚度減小1mm，觀察其分析結(jié)果是否滿足強度和剛度要求。由于本文有限元模型有殼單元（shell 63）分析箱型梁板所以只需要修改相應(yīng)板厚的實常數(shù)再重新求解，即可方便的考察優(yōu)化后主梁的力學(xué)特性。
4.3 優(yōu)化結(jié)果分析
圖4為優(yōu)化后主梁的綜合應(yīng)力分布云圖，該圖顯示，最大綜合應(yīng)力為17.958MPa，符合強度要求，最大綜合應(yīng)力發(fā)生在主梁吊耳吊裝孔工作面附近?？疾炱渚C合應(yīng)力分布，除主梁吊耳吊裝孔附近應(yīng)力集中處的應(yīng)力數(shù)值比較高外，
主梁中部應(yīng)力為58.989~117.974MPa。箱型梁兩端直角和銳角過渡焊縫處應(yīng)力為154.296~180.011 MPa，考慮鋼板焊接后一般應(yīng)予以打磨，焊縫處呈圓角過渡，而有限元分析模型對此圓角作了簡化，造成局部應(yīng)力集中，此處應(yīng)力值應(yīng)比實際值高[3
圖5為優(yōu)化后主梁的變形情況，垂直方向最大位移為23.095mm，水平方向最大位移為8.770mm，符合剛度要求，最大位移發(fā)生在主梁中部。主梁結(jié)構(gòu)優(yōu)化前后對比見表2.
通過以上比較可知，優(yōu)化主梁箱型梁鋼板厚度后，主梁強度、剛度并未明顯降低，滿足工作要求；最大應(yīng)力發(fā)生位置也無改變，主梁重量降低了8.572%。較好地達(dá)到優(yōu)化主梁鋼結(jié)構(gòu)的目的。
此外，從以上有限元分析結(jié)果可知：主梁綜合應(yīng)力和切應(yīng)力值較高的部位為吊耳吊裝孔附近區(qū)域和箱型梁兩端鋼板焊接處，雖然分析結(jié)果顯示強度滿足工作要求，但對該處作強化處理可有效提高實驗壽命和安全性。應(yīng)采用改善焊接工藝或焊接加強板的方式予以加固。
五．結(jié)語
本文結(jié)合設(shè)計人員的設(shè)計經(jīng)驗和有限元分析功能，通過快速虛擬試驗的方式尋求相對優(yōu)化的結(jié)構(gòu)設(shè)計方案。與傳統(tǒng)的優(yōu)化的結(jié)構(gòu)設(shè)計方法相比較，該方法得到的并非數(shù)學(xué)規(guī)劃概念上的最優(yōu)解，但其容易實現(xiàn)。此外，本文算例已經(jīng)投產(chǎn)，其結(jié)果為同類橋式起重機鋼結(jié)構(gòu)優(yōu)化設(shè)計提供了有益的參考。
參考文獻(xiàn)：
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[2] 徐格寧。起重運輸機金屬結(jié)構(gòu)設(shè)計[M]。北京：機械工程出版社，1995.
[3] 于蘭峰，周志鰲。鐵路起重機轉(zhuǎn)臺有限元分析[J]。計算力學(xué)學(xué)報，2003，20（5）：627-630
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