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黑龍江工程學(xué)院本科生畢業(yè)設(shè)計(jì)
附錄A
Performance Kinematics Simulation of Macpherson
Suspension Based on ADAMS
WANG Yuefang, WANG Zhenhua
(Department of Vehicle & Power Engineering,College of Mechatronics Engineering,North University of China, Taiyuan, Shanxi, 030051, China)
Phone:+863513920300 Fax:+863513922364 E-Mail:wangyuefang2005@nuc.edu.cn
Abstract: The paper discusses a basic simulation way on founding a front suspension simulation model. It applies on method of multi-body dynamics and uses virtual prototyping technology software ADAMS building up Macpherson suspension entity mold. It analyzes the relations between a Macpherson suspension system and wheel alignment characteristic through kinematics simulation, and obtains the changing trend of the wheel alignment parameters. This provides theoretical foundation with further optimization design.
Key words: Macpherson Suspension; Kinematics Simulation; ADAMS
1. Introduction
Suspension system is a key part for cars, and has decisive effect on car drivability, stability, and comfortability. Because of its characteristics of simple structure, low cost and space economy, Macpherson suspension has become the most popular independent suspension since its emergence. Hence, the kinematics analysis of Macpherson suspension has great significance. ADAMS (Automatic Dynamic Analysis of Mechanical System) is a simulation software of mechanical system used most widely in the world. Based on the ADAMS virtual model technology, the automobile suspension is regard as a multi-body system which parts connect and motion each other. With the help of ADAMS/View, this paper established multi-body dynamics model of Macpherson front suspension of some car which is increasingly wide used in modern car, and the effects of suspension parameters when wheel travel or turn were studied. The ADAMS entity numeric suspension kinetics simulation provides an efficient and updated tool for developing suspension system.
2. Simulation model
2.1 Front suspension subsystem simulation model
Firstly, three-dimensional model of Macpherson suspension system in the Pro/E according to acquired geometric parameters is established. Secondly, ADAMS/CAR model is imported by utilizing MECHANISM/Pro, and the geometric characteristic parameters can be obtained from Pro/E three-dimensional documents. The founding model time is short and very accurate. Fig.1 is the model of Macpherson suspension subsystem. Table 1 is the constraints relationship between rigid bodies of front Macpherson suspension.
Fig.1 Front Macpherson suspension subsystem
1-lower triangle swinging arm 2-universal joint3-subsidiary car frame
4-upper suspension support 5-tie rod 6-wheel rim 7-driving axle
8-driving joint axle9-shock absorber 10-rubber liner
2.2 Steering subsystem simulation model
Gear and rack steering system model adopts partial coordinate system. The base point lies in center of circle of steering wheel. The direction of x, y, z axle is radial, tangential, normal of steering wheel separately. Figure 2 is the model which contains six rigid bodies that are rack, rack shell, gear axle, middle axle, steering limb and steering wheel axle. Three assembled bodies connect tie rod, subsidiary car frame and car body. Fig.2 is the model of steering system. Table 2 is the constraints relationship between rigid bodies of steering subsystem.
Fig.2 The model of steering subsystem
2.3 Simulation model of front Macpherson suspension system
Front Macpherson suspension subsystem and steering subsystem models from ADAMS/CAR that have been established are invoked. Then, combined parameters are input. So far , front Macpherson suspension model is finished. Figure 3 is the kinematics simulation model of Macpherson suspension.
Fig.3 Suspension simulation model
3. Kinematics simulation analyses
3.1 Data process
Initial simulation conditions uniform actual parameters of the researched car. Utilizing ADAMS/CAR model simulates bilateral parallel travel and opposite direction travel. So, the alteration of camber angle, kingpin inclination angle, caster angle and toe angle are analyzed. The structure of Macpherson suspension’s left and right is symmetrical, it is totally the same to alignment parameters, only the left wheel alignment parameters are analyzed[3]. The range that this car beats is 150mm -130mm actually. Under two kinds of operating modes, the comparison of changed curves on wheel alignment parameters are shown in Fig. 4-7.
Fig.4 Camber angle vs wheel travel
Fig.5 Caster angle vs wheel travel
Fig.6 Toe angle vs wheel travel
Fig.7 Kingpin inclination angle vs wheel travel
3.2 Discussion and analysis
(1)In the process of wheel parallel travel and opposite travel, the alignment parameters change with the change of wheel vertical shift. In Fig.4, camber angle reduces firstly and increases secondly. The changing amount is 0.9786. The change of camber angle contains two parts: the change of camber angle that comes from car body roll and the changing amount of camber angle that relates car body travel. In Fig.5, the change of caster angle with the wheel vertical shift rise sharply.
(2)Under two kinds of operating modes of wheel parallel travel and opposite travel, Fig.6 is shown , the change of toe angle is obviously. Under the operating modes of opposite travel, toe angle increases from -0.8029 to 1.6844. Its change affects car drivability and stability.
(3)As we can see in Fig.4 and Fig.7, when the wheel travels downward, the change range that is from 0~-130mm, the changing trend of kingpin inclination angle is opposite to camber angle. This could aggravate the wheel wear. But, according to the theoretical relationship and adjust, proper and acceptedcorresponding relation can be obtained.
4. Conclusion
This paper discusses kinematics simulation analysis on founding a front Macpherson suspension simulation model that uses technology software ADAMS. Three conclusions are as follows:
(1)ADAMS/CAR model is imported from Pro/E by utilizing MECHANISM/Pro, but model can also be imported to SolidWork or UG in STEP format, then, imported to ADAMS in ParaSolid format.
(2)The original wheel orientation parameters of Macpherson suspension meet the require. These indicate that the model is rational. The wheel wear range is accepted.
(3)The change trend of the wheel alignment parameters is gained through kinematics simulation analysis of Macpherson suspension. Wheel alignment characteristic has effect on full-vehicle capability through suspension and Camber angle. On contrary, full-vehicle motion characteristic affects wheel alignment characteristic through suspension. In a word, virtual prototyping technology software ADAMS can greatly predigest design program and shorten exploitive cycle, greatly reduce exploitive expense and cost, clearly improve product quality and system capability to get optimized and innovated product.
附錄B
基于ADAMS的麥弗遜懸架運(yùn)動學(xué)仿真分析
王月芳,王振華
(中北大學(xué)車輛與動力工程系, 山西太原030051)
摘要:本文討論了一種建立麥弗遜前懸架模型的基本仿真分析方法。它運(yùn)用多體動力學(xué)的理論并在虛擬樣機(jī)技術(shù)軟件ADAMS上建立麥弗遜懸架實(shí)體模型。通過運(yùn)動學(xué)仿真,分析了麥弗遜懸架系統(tǒng)與車輪定位參數(shù)特性之間的關(guān)系,得到車輪定位參數(shù)的變化趨勢。這些為進(jìn)一步優(yōu)化設(shè)計(jì)提供了理論依據(jù)。
關(guān)鍵詞: 麥弗遜式懸架;運(yùn)動仿真;ADAMS
1. 前言
懸架系統(tǒng)是汽車的關(guān)鍵部件,對汽車的動力性,操縱穩(wěn)定性,舒適性有決定性影響。由于它的結(jié)構(gòu)簡單,成本低,節(jié)省空間的特點(diǎn),麥弗遜懸架從它誕生以后就成為了應(yīng)用最廣泛的獨(dú)立懸架類型。因此對麥弗遜懸架進(jìn)行運(yùn)動學(xué)分析具有重要意義。
ADAMS (Automatic Dynamic Analysis of Mechanical System)是世界上應(yīng)用最廣泛的機(jī)械系統(tǒng)仿真軟件?;贏DAMS虛擬樣機(jī)技術(shù),汽車懸架可以看作是各部件相互連接和運(yùn)動的多體系統(tǒng)。借助于ADAMS/View,本文建立了某轎車的麥弗遜前懸架(在現(xiàn)代轎車上應(yīng)用越來越廣泛)的多體動力學(xué)模型,并研究了當(dāng)車輪跳動,轉(zhuǎn)動時(shí),懸架結(jié)構(gòu)參數(shù)產(chǎn)生的影響。在ADAMS上進(jìn)行懸架動力學(xué)仿真為懸架技術(shù)的發(fā)展提供了有效而且及時(shí)的方法。
2. 仿真模型
前懸架系統(tǒng)建模
首先,根據(jù)必要的幾何參數(shù),在Pro/E中建立麥弗遜懸架的三維模型。其次,通過MECHANISM/Pro,ADAMS/CAR模型被導(dǎo)入,而且模型的幾何參數(shù)通過Pro/E三維模型文件也能得到。建?;ㄙM(fèi)時(shí)間短,并且精確。圖1所示的即為麥弗遜懸架子系統(tǒng)。表1列出了懸架各部件間的連接關(guān)系。
圖1:麥弗遜前懸架
1-下三角擺臂;2-轉(zhuǎn)向節(jié)3-副車架;4-懸架上支架5-轉(zhuǎn)向橫拉桿6-輪轂;7-傳動軸8-傳動軸節(jié)9-減震器;10-橡膠襯套
轉(zhuǎn)向系統(tǒng)模型
齒輪齒條式采用局部坐標(biāo)系,坐標(biāo)原點(diǎn)位于轉(zhuǎn)向盤圓心處,x、y、z軸的方向分別為轉(zhuǎn)向盤的徑向、切向、法向。模型如圖2,包括6個(gè)剛體,分別為齒條、齒條殼體、齒輪軸、中間軸、轉(zhuǎn)向管柱和轉(zhuǎn)向盤軸。3個(gè)裝配剛體,分別用來連接轉(zhuǎn)向橫拉桿、副車架和車身。剛體之間的相互約束關(guān)系如表2。
Fig.2 轉(zhuǎn)向系統(tǒng)模型
2.3 建立前懸架仿真平臺模型
在ADAMS/CAR 中調(diào)用上面建立好的前懸架子系統(tǒng)和轉(zhuǎn)向子系統(tǒng),輸入相關(guān)參數(shù),完成麥弗遜式懸架的建模。懸架運(yùn)動學(xué)仿真模型如圖3所示。
圖3:懸架運(yùn)動學(xué)仿真平臺模型
3. 運(yùn)動學(xué)仿真分析
3.1 數(shù)據(jù)處理
仿真初始條件和此車實(shí)況參數(shù)保持一致,利用ADAMS/CAR模塊進(jìn)行雙側(cè)平行跳動和反向跳動仿真,分析車輪外傾角、主銷內(nèi)傾角、主銷后傾角及前束角的變化。
該麥?zhǔn)角皯壹茏笥医Y(jié)構(gòu)對稱,定位參數(shù)完全一樣,則只分析左車輪定位參數(shù)。此車實(shí)際跳動的范圍為150mm~-130mm,在兩種工況下,車輪定位參數(shù)變化曲線對比如圖4~圖7所示。
圖4 外傾角隨車輪垂直位移的變化圖5 后傾角隨車輪垂直位移的變化
圖6 前束角隨車輪垂直位移的變化
圖7 內(nèi)傾角隨車輪垂直的位移的變化
3.2 小結(jié)與分析
(1)輪胎平行跳動和異向跳動的過程中,定位參數(shù)隨垂直位移的變化而變化,在圖4中,外傾角先減小后增大,變化量為0.9768。外傾角變化包括兩部分,一是由車身側(cè)傾產(chǎn)生的外傾角變化,二是相對車身跳動的車輪外傾變化量。
在圖5中,隨著車輪垂直運(yùn)動,車輪后傾角變化曲線上升很快。
(2)車輪在平行和異向跳動工況下,如圖6所示,前束角變化差異較大,異向跳動下前束角由最小-0.8029 增加到1.6844。其變化直接影響車輛的操縱穩(wěn)定性,
(3)由圖4和圖6看出,在車輪向下跳動時(shí), 即從0~- 130mm,外傾角的變化趨勢與前束角的變化趨勢相反,這樣會加劇輪胎的磨損,根據(jù)理論上的關(guān)系和調(diào)整,可得到合理的或可接受的對應(yīng)關(guān)系。
4.結(jié)論
本文利用ADAMS 軟件建立了某車的前麥弗遜式懸架仿真模型并進(jìn)行了運(yùn)動仿真。由此得出以下三點(diǎn);
(1)在從Pro/E導(dǎo)入ADAMS時(shí),可以用MECHANISM/Pro接口模塊,也可以先以STEP格式導(dǎo)入到SolidWork 或UG 里,再以Parasolid 格式導(dǎo)入ADAMS 中;
(2)麥弗遜懸架的初始車輪定位參數(shù)滿足要求。這表明懸架模型是合理的,車輪磨損范圍是可以接受的;
(3)通過仿真分析明確了車輪在跳動過程中,車輪定位參數(shù)的變化趨勢。車輪定位特性通過懸架與車身外傾角對整車產(chǎn)生影響;反之,整車的運(yùn)動特性通過懸架對車輪定位特性進(jìn)行影響的。
總之,虛擬樣機(jī)技術(shù)軟件ADAMS能大大簡化設(shè)計(jì)程序,縮短開發(fā)周期,大大減少開發(fā)費(fèi)用和代價(jià),明顯改進(jìn)產(chǎn)品質(zhì)量和系統(tǒng)性能,得到優(yōu)化的創(chuàng)新的產(chǎn)品。
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