FSAE賽車雙橫臂式前懸架設(shè)計(jì)【說明書+CAD+PROE】
FSAE賽車雙橫臂式前懸架設(shè)計(jì)【說明書+CAD+PROE】,說明書+CAD+PROE,FSAE賽車雙橫臂式前懸架設(shè)計(jì)【說明書+CAD+PROE】,fsae,賽車,雙橫臂式前,懸架,設(shè)計(jì),說明書,仿單,cad,proe
黑龍江工程學(xué)院本科生畢業(yè)設(shè)計(jì)
附 錄
Kinematic Characterization and Optimization of Vehicle Front-suspension Design Based on ADAMS
Abstract： To improve the suspension performance and steering stability of light vehicles, we built a kinematic simulation model of a whole independent double-wishbone suspension system by using ADAMS software, created random excitations of the test platforms of respectively the left and the right wheels according to actual running conditions of a vehicle, and explored the changing patterns of the kinematic characteristic parameters in the process of suspension motion. The irrationality of the suspension guiding mechanism design was pointed out through simulation and analysis, and the existent problems of the guiding mechanism were optimized and calculated. The results show that all the front-wheel alignment parameters, including the camber, the toe, the caster and the inclination, only slightly change within corresponding allowable ranges in design before and after optimization. The optimization reduces the variation of the wheel-center distance from 47.01 mm to a change of 8.28 mm within the allowable range of -10 mm to 10 mm, promising an improvement of the vehicle steering stability. The optimization also confines the front-wheel sideways slippage to a much smaller change of 2.23 mm; this helps to greatly reduce the wear of tires and assure the straight running stability of the vehicle.
Keywords： vehicle suspension; vehicle steering; riding qualities; independent double-wishbone suspension; kinematic characteristic parameter; wheel-center distance; front-wheel sideways slippage
1 Introduction
The function of a suspension system in a vehicle is to transmit all forces and moments exerted on the wheels to the girder frame of the vehicle, smooth the impact passing from the road surface to the vehicle body and damp the impact-caused vibration of the load carrying system. There are many different structures of vehicle suspension, of which the independent double-wishbone suspension is most extensively used. An independent double-wishbone suspension system is usually a group of space RSSR (revolute joint - spherical joint -spherical joint - revolute joint) four-bar linkage mechanisms. Its kinematic relations are complicated, its kinematic visualization is poor, and performance analysis is very difficult. Thus, rational settings of the position parameters of the guiding mechanism are crucial to assuring good performance of the independent double-wishbone suspension. The kinematic characteristics of suspension directly influence the service performance of the vehicle, especially steering stability, ride comfort, turning ease, and tire life.
In this paper, we used ADAMS software to build a kinematic analysis model of an independent double-wishbone suspension, and used the model to calculate and optimize the kinematic characteristic parameters of the suspension mechanism. The optimization results are helpful for improving the kinematic performance of suspension.
2 Modeling independent double-wishbone suspension
The performance of a suspension system is reflected by the changes of wheel alignment parameters when the wheels jump. Those changes should be kept within rational ranges to assure the designed vehicle running performance. Considering the symmetry of the left and right wheels of a vehicle, it is appropriate to study only the left or the right half of the suspension system to understand the entire mechanism, excluding the variation of WCD (wheel center distance). We established a model of the left half of an independent double-wishbone suspension system as shown in Figure 1.
3 Kinematic simulation analysis of suspension model
Considering the maximum jump height of the front wheel, we positioned the drives on the translational joints between the ground and the test platform, and imposed random displacement excitations on the wheels to simulate the operating conditions of a vehicle running on an uneven road surface.
The measured road-roughness data of the left and right wheels were converted into the relationship between time and road roughness at a certain vehicle speed. The spline function CUBSPL in ADAMS was used to fit and generate displacement-time history curves of excitation. The simulation results of the suspension system before optimization are illustrated in Figure 2.
The camber angle, the toe angle, the caster angle and the inclination angle change only slightly within the corresponding designed ranges with the wheel jumping distance. This indicates an under-steering behavior together with an automatic returnability, good steering stability and safety in a running process. However, WCD decreases from 1 849.97 mm to 1 896.98 mm and FWSS from 16.48 mm to -6.99 mm, showing remarkable variations of 47.01 mm and 23.47 mm, respectively. Changes so large in WCD and FWSS are adverse to the steering ease and straight-running stability, and cause quick wear, thus reducing tire life.
For independent suspensions, the variation of WCD causes side deflection of tires and then impairs steering stability through the lateral force input. Especially when the right and the left rolling wheels deviate in the same direction, the WCD-caused lateral forces on the right and the left sides cannot be offset and thus make steering unstable. Therefore, WCD variation should be kept minimum, and is required in suspension design to be within the range from -10 mm to 10 mm when wheels jump. It is obvious that the WCD of non-optimized structure of the suspension system goes beyond this range. The structure needs modifying to suppress FWSS and the change of WCD with the wheel jumping distance.
ADMAS software is a strong tool for parameter optimization and analysis. It creates a parameterization model by simulating with different values of model design variables, and then analyzes the parameterization based on the returned simulation results and the final optimization calculation of all parameters. During optimization, the program automatically adjusts design variables to obtain a minimum objective function [8-10]. To reduce tire wear and improve steering stability, the Table 1 Values of camber angle α , toe angle θ , caster angle γ and inclination angle β before and after optimization
Table 1 The data tables of optimize the results
4 Conclusions
The whole kinematic simulation model of an independent double-wishbone suspension system built by using ADAMS software with the left and the right suspension parts under random excitations can improve the calculation precision by addressing the mutual impacts of kinematic characteristic parameters of the left and the right suspension parts under random excitations. The optimization can overcome the problem of the too large variation of WCD and overly large FWSS with the wheel jumping distance. The kinematic characteristic parameters of the suspension system reach an ideal range, demonstrating that the optimization protocol is feasible. From a practical perspective, the optimization is expected to reduce tire wear, and remarkably improve suspension performance and vehicle steering stability.
Figure 1 simple picture of suspension
Figure 2 Curve with the parameters of the suspension
基于ADAMS前懸架優(yōu)化設(shè)計(jì)
摘要：為了提高輕型車輛性能和行駛穩(wěn)定，我們使用ADAMS軟件建立一個(gè)獨(dú)立雙橫臂懸架系統(tǒng)運(yùn)動(dòng)仿真模型，并建立隨機(jī)激勵(lì)的測(cè)試平臺(tái)，根據(jù)車輛實(shí)際運(yùn)行條件，探討懸架的運(yùn)動(dòng)學(xué)特征參數(shù)的變化。通過仿真和優(yōu)化的可以對(duì)懸架設(shè)計(jì)進(jìn)行相關(guān)的指導(dǎo)。試驗(yàn)表明，所有的前輪定位參數(shù)，包括前輪前束角，主銷內(nèi)傾角，注銷后傾角，前輪外傾角都可以得到優(yōu)化。例如只要在仿真前或后改變一個(gè)很小的量，車輪中心距就可以從減小到許用范圍從而改善了車輛的操縱穩(wěn)定性。此外還優(yōu)化了前輪側(cè)向滑動(dòng)量，使之減小到，更有助于減少輪胎磨損，保證車輛的行駛穩(wěn)定性。
關(guān)鍵詞：汽車懸架；車輛轉(zhuǎn)向；駕駛性能；獨(dú)立雙橫臂懸架；運(yùn)動(dòng)學(xué)特征參數(shù)；輪中心距；前輪側(cè)向滑移
1簡介
汽車懸架的功用時(shí)承受來自地面?zhèn)髦淋嚿淼臎_擊，保證車輛在行駛過程中的操縱穩(wěn)定性和平順性的系統(tǒng)。懸架有很多種類，其中雙橫臂獨(dú)立懸架時(shí)應(yīng)用最為廣泛的一種。獨(dú)立的雙橫臂懸掛系統(tǒng)通常是一組空間四連桿機(jī)制。其運(yùn)動(dòng)關(guān)系復(fù)雜，性能分析是非常困難。因此，合理的設(shè)置參數(shù)對(duì)指導(dǎo)其設(shè)計(jì)是至關(guān)重要的。為確保汽車具有良好的性能，特別是操縱穩(wěn)定性，乘坐舒適，轉(zhuǎn)向緩和，輪胎壽命。因此對(duì)懸架的設(shè)計(jì)時(shí)非常重要的。在本文中，我們使用ADAMS軟件建立一個(gè)獨(dú)立的雙橫臂懸掛系統(tǒng)的運(yùn)動(dòng)學(xué)分析模型，并利用該模型計(jì)算和優(yōu)化的運(yùn)動(dòng)特征參數(shù)。優(yōu)化的結(jié)果，有助于知道我們對(duì)懸架的設(shè)計(jì)。
2獨(dú)立雙橫臂懸架的建模?
當(dāng)車輪跳東時(shí)懸掛系統(tǒng)的性能受到車輪定位參數(shù)變化的影響。這些變化應(yīng)保持在合理的范圍，以保證所設(shè)計(jì)的車輛行駛性能?？紤]到獨(dú)立懸架的左，右車輪是對(duì)稱的，因此我們只要研究左側(cè)或右側(cè)的懸掛系統(tǒng)，就可以了解整個(gè)懸架系統(tǒng)，但不包括車輪中心的距離的變化 。我們建立一個(gè)如圖1所示的模型，此模型為獨(dú)立雙橫臂懸掛系統(tǒng)的左側(cè)系統(tǒng)。
3懸架模型運(yùn)動(dòng)學(xué)仿真分析
考慮到前輪最大的跳動(dòng)高度，我們?cè)诘孛婧蜏y(cè)試平臺(tái)放置一個(gè)上、下運(yùn)動(dòng)的驅(qū)動(dòng)幅，并加上車輛在路面上實(shí)際運(yùn)動(dòng)時(shí)上、下運(yùn)動(dòng)的關(guān)系加上隨機(jī)激勵(lì)。
實(shí)測(cè)的道路粗糙度數(shù)據(jù)是根據(jù)左，右車輪在一定時(shí)間內(nèi)、一定車速和路面的不平度轉(zhuǎn)化的。并對(duì)樣條函數(shù)斯進(jìn)行了擬合，并產(chǎn)生位移時(shí)程曲線的激勵(lì)。經(jīng)過仿真可以得到前懸架系統(tǒng)隨各運(yùn)動(dòng)參數(shù)變化而變化的曲線，如圖2所示。
隨著車輪的跳動(dòng)，前輪外傾角、前輪前束角、主銷后傾角和主銷內(nèi)傾角在相應(yīng)的設(shè)計(jì)范圍內(nèi)變化很小。這表明行駛時(shí)將產(chǎn)生一個(gè)的回正力矩，來保證行駛的平順性和安全性，然而側(cè)向滑動(dòng)量卻從上升到，車輪跳動(dòng)量從下降到。從中可以看到對(duì)影響行駛穩(wěn)定性和加速輪胎磨損從而降低輪胎壽命的側(cè)向滑動(dòng)量和車輪跳動(dòng)量都具有明顯的變化。他們的變化量分別為和。
對(duì)于獨(dú)立懸架，側(cè)向滑動(dòng)量的變化對(duì)輪胎的磨損具有負(fù)面影響，并通過側(cè)向力的作用影響駕駛的平穩(wěn)性，特別是當(dāng)左右車輪同向偏離時(shí)。側(cè)向力造成的權(quán)利和左右兩側(cè)不能抵消，從而使轉(zhuǎn)向不穩(wěn)定。因此，側(cè)向滑動(dòng)量的變化應(yīng)保持最低限度，按照懸架設(shè)計(jì)要求，當(dāng)車輪跳動(dòng)時(shí)其值必須控制在～之間。很明顯，側(cè)向滑動(dòng)量的非結(jié)構(gòu)優(yōu)化的懸掛系統(tǒng)超出了這個(gè)范圍。因此，此結(jié)構(gòu)必須根據(jù)車輪的跳動(dòng)量改變。
ADMAS是一個(gè)具有優(yōu)化和仿真強(qiáng)強(qiáng)大功能的軟件。它通過創(chuàng)建一個(gè)參數(shù)化模型，通過改變?cè)O(shè)計(jì)變量的值再返回到模型，模型再根據(jù)返回的值進(jìn)行優(yōu)化分析，經(jīng)過反復(fù)的優(yōu)化分析目標(biāo)函數(shù)就可以調(diào)整到最小。以減少輪胎磨損，提高操縱穩(wěn)定性為目標(biāo)函數(shù)進(jìn)行優(yōu)化，表1的中的值分別為車輪外傾角，主銷內(nèi)傾角角 ，前輪前束角和注銷后傾角優(yōu)化前后值的比較。
表1 優(yōu)化結(jié)果數(shù)據(jù)表
4結(jié)論
獨(dú)立的雙橫臂懸架系統(tǒng)的整個(gè)運(yùn)動(dòng)仿真過程是建立在ADAMS軟件上，由于左右懸架自由運(yùn)動(dòng)可以提高在隨機(jī)激勵(lì)下的計(jì)算精度，解決運(yùn)動(dòng)學(xué)特征參數(shù)的相互影響的。優(yōu)化可以解決側(cè)向滑動(dòng)量變化太大和車輪跳動(dòng)距離過大的問題。使懸架系統(tǒng)的運(yùn)動(dòng)學(xué)特征參數(shù)在一個(gè)理想的范圍變化，這就表明優(yōu)化結(jié)果是可行的。從現(xiàn)實(shí)的角度來看，優(yōu)化可以預(yù)期將輪胎的磨損降低到最低，并顯著提高車輛的行駛性能和車輛懸架操縱穩(wěn)定性。
圖1 懸架模型簡圖
圖2 懸架隨參數(shù)變化曲線
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