載重汽車車架有限元分析

載重汽車車架有限元分析,載重汽車,車架,有限元分析 畢 業(yè) 設 計（論 文）外 文 參 考 資 料 及 譯 文 譯文題目： Car safety 汽車安全裝備 學生姓名： 專　　業(yè)： 所在學院： 指導教師： 職　　稱： CAR SAFETY Car safety is the avoidance of car accidents or the minimization of harmful effects of accidents, in particular as pertaining to human life and health. Special safety features have been built into cars for years, some for the safety of car’s occupants only, some for the safety of others. Auto safety is divided into active and passive safety two kinds, active safety refers to the ability of car prevent accidents, passive safety in the event of accident refers to the situation, the ability of car protect crew. When the automobile accident harm, to crew member in the momentary. For example, a speed of 50 kilometers/crash when positive, its occurrence time only one in ten seconds. In such a short time for preventing damage of crew must set safety equipment, mainly have belts, impact-proof type body and airbags protection system(Supplemental Inflatable Restraint System).Because many accidents are unavoidable, so passive security is also very important, airbags as passive security research, due to the convenient use, the effect is remarkable, cost is not high, obtained a rapid development and popularization. Every year, tens of thousands died in the traffic accident. Main reasons are: drunk or take some medications driving, driving when inattention, fatigue driving, driving or encounter risk road incidents as follows snow, certainly some pits and across the road animals. Every year tens of thousands of people are killed in road accidents. Major factors in accidents include driving under the influence of alcohol or other drugs, inattentive driving, driving while fatigued, reckless driving, or encounters with road hazards such as snow, potholes and crossing animals. 1 History Car safety became an issue almost immediately after the invention of the automobile, when Nicolas Joseph Cughot crashed his steam-powered “Fardier” against a wall in 1771. The first recorded automobile fatality was Bridget Driscoll on August 17, 1896 in London. The United States Department of Transportation (DOT) was established by the United States Congress on October 15, 1966 with automobile safety one of its purposes. The National Transportation Safety Board (NTSB) was created as an independent organization on April 1, 1967, but was reliant on the DOT for administration and funding. However, in 1975 the organization was made completely independent by the Independent Safety Board Act. The NTSB and its European equivalent, Euro NCAP have issued standard safety tests for all new automobiles. In June, 2004 the NTSB released new tests designed to test the rollover risk of new cars and SUVs. Only the Mazda RX—8 got a 5-star rating. However, the correlation between official crash test results and road deaths in vehicles is not exact. An alternative method of assessing vehicle safety is to study the road accident statistics on a model-by-model basis. Despite technological advances, the death toll of car accidents remains high: about 40,000 people die every year in the US. [1]While this number increases annually in line with rising population and increased travel, the rate per capita and per vehicle miles travelled decreases. In 1996 the US has about 2 deaths per 10 000 motor vehicles, comparable to 1.9 in Germany, 2.6 in France, and 1.5 in the UK. In 1998 there were 3 421 fatal accidents in the UK, the fewest since 1926. A much higher number of accidents result in permanent disability. Humans as traffic participants play a major role with respect to failure that might lead to an accident.Table.25-1 shows the involvement of various groups related to the occurrence of accidents. The main group is car occupants. Some data indicate that the driver is responsible for more than 80% of all accidents. 2 Pregnant women When pregnant, women should continue to use seatbelts and airbags properly. A University of Michigan study found that “unrestrained or improperly restrained pregnant woman are 5.7 times more likely to have an adverse fetal outcome than properly restrained pregnant women.” If seatbelts are not long enough, extensions are available from the car manufacturer or an aftermarket supplier. 3 Children Car safety is especially critical for young children, as car safety is generally designed for normal sized adults. Safety features that could save an adult can actually cause more damage to a child than if the feature was not there. All children age 12 and under should ride in the back seat. This is especially the case if there are airbags in the front seat, as airbags are only designed to protect adults and may injure children. Child safety locks prevent children from accidentally opening doors from inside the vehicle, even if the door is unlocked. The door, once unlocked, can then be opened only from the outside. 3.1 Infants Newborn babies should be put in a car seat until they weigh at least 20 or 22 pounds (10 or11 kg). [2]These carriers are designed to be placed in the rear seat and face towards the rear with the baby looking towards the back window. Some of these carriers are “convertibles” which can also be used forward facing for older children. With infants, these should only be used facing the rear. Harness straps should be at or below shoulder level. A rear-facing infant restraint must never be put in the front seat of a vehicle with a front passenger air bag. A rear-facing infant restraint places an infant’s head close to the airbag module, which can cause severe head injuries or death if the air bag deploys. Modern cars include a switch to turn off the airbag system of the passenger seat, in which case a child-supporting seat must be installed. 3.2 Toddlers Toddlers over 1 year old and between 20 pounds and 40 pounds (10 kg and 20 kg) should be placed in forward facing child seats or convertibles placed in the rear seat. Harness straps should be at or above the child’s shoulders. 3.3 Young children Children who weigh less than 80 pounds (40 kg), are younger than 8, or are shorter than 4 feet 9 inches (1.4 m) are advised to use belt positioning booster seats which raise them to a level that allows seat belts to work effectively. These seats are forward facing and must be used with both lap and shoulder belts. Make sure the lap belt fits low and tight across the lap/upper thigh area and the shoulder belt fits snug crossing the chest and shoulder to avoid abdominal injuries. There are two main types of booster seats. If your car’s back seat is lower than your child’s ears, use a high back booster seat to help protect your child’s head and neck. If your car’s seat back is higher than your child’s ears, you can use a backless booster seat. 4 Avoidance 4.1 Safety features To make driving safer and prevent accidents from occurring, cars may have the following active safety features: (1) Turn signals and brake lights, including center high Mounted stop lamps (CHMSL). (2) Anti-lock braking system (ABS) with EBPD pad (electronic brake pressure distribution), which prevents the brakes from locking and losing traction while braking. This shortens stopping distances in almost all cases. See also: Emergency braking assistance (EBA). (3) Electronic stability controls, which use various sensors to intervene when the car senses a possible loss of control. The car’s computer can reduce power from the engine and even apply the brakes to prevent the car from under steering or over steering. (4) Traction control system(TCS). (5) Electronic stability program (ESP) or electronic stability control (ESC), with Acceleration slip regulation (ASR) and electronic differential lock (EDL). (6) Lane departure warning system (LDWS). (7) Directional headlamps. (8) Low center of gravity and other conventional features promoting good car handling and braking. 4.2 Damage control When an accident is imminent, various passive safety systems work together to minimize damage to those involved. Much research has been done using crash test dummies to make modern cars safer than ever. Recently, attention has also been given to the cars design regarding the safety of pedestrians in car-pedestrian collisions. Controversial proposals in Europe would require cars sold there to have a minimum/maximum hood height. This has caused automakers to complain that the requirements will restrict their design choices, resulting in ugly cars. Others have pointed out that a notable percentage of pedestrians in these accidents are drunk. From 2006 the use of “bull bars” (known as “roof bars” in Austria), in fashion on 4*4s and SUVs will be illegal. (1) Seatbelts (or safety belts) keep a person from being thrown forward or ejected from the Vehicle. Ford introduced inflatable rear seatbelts on the 2011 Ford Explorer. Think of these as a cross between an airbag and a seatbelt. Ford says that it designed the inflatable seatbelts to help reduce head, neck and chest injuries for rear-seat passengers, who are often children and the elderly and who can be more vulnerable to such injuries. The seatbelts have made their way into other Ford vehicles such as the Flex and the Lincoln lineup. (2) Front airbags inflate in a medium speed head on collisions to cushion the blow of a head on the dashboard or steering wheel. (3) Side airbags inflate in a side (T-bone) collision to cushion the torso. (4) Curtain airbags protect the heads of passengers in a side collision. (5) Knee Airbags: This small airbag is designed to minimize injuries to the lower limbs as they make contact with the dashboard. Knee airbags are located in the foot well, under the steering column on the driver side and under the glove box on the passenger side. Ford introduced a new passenger knee airbag design on the 2015 Ford Mustang. Rather than use the traditional fabric design, this new airbag consists of an inflatable, molded plastic bladder, wedged between the inner and outer glove box door panels. In the event of an accident, an inflator fills the bladder, extending the entire glove box outer door panel toward the front passenger's legs, Ford says. Once deployed, the outer door helps to provide cushioning in a manner similar to a traditional knee airbag. The new design is 65 percent lighter than the previous system and results in slightly more legroom for the passenger. (6) Bumpers to withstand low-speed collisions without damaging bodywork. (7) Crumple zones absorb the energy of an impact when the car hits something. (8) Crash compatibility can be improved by matching vehicles by weight and by matching crumple zones with points of structural rigidity, particularly for side-on collisions. (9) Cage construction is designed to protect vehicle occupants. Some racing vehicles have a tubular roll cage. (10) Reinforced side door structural members. (11) Fuel pump shutoff devices turn off gas flow in the event of a collision for the purpose of preventing gasoline fires. (12) Light weight：The possible damage a vehicle can do to outside people and things is roughly proportional to its kinetic energy, which is its weight mutiplying the square of its Speed. 4.3 new technology In the immediate future, there will be more developments in active safety, such as pre-collision systems and lane departure warnings, to prevent accidents, rather than passive safety, such as airbags and car crumple zones, that minimize injuries during an accident. The sensor, processing and "by-wire" technologies have advanced very quickly over the last few years. This lets manufacturers develop a wide variety of high-level driver assistance features to improve crash avoidance or crash mitigation. 汽車安全裝備 汽車安全裝備可避免車禍或使車禍的傷害減到最小，尤其是使與人的生活和健康有關的傷害最小。好幾年前汽車上就已經安裝有專門的安全裝置，有些是為車上乘員的安全，有些是為他人的安全。 汽車的安全性分為主動安全和被動安全兩種，主動安全是指汽車防止發(fā)生事故的能力，被動安全是指在萬一發(fā)生事故的情況下，汽車保護乘員的能力。當汽車發(fā)生事故時，對乘員的傷害是在瞬間發(fā)生的。例如，以車速50公里/時進行正面撞車時，其發(fā)生時間只有十分之一秒左右。為了在這樣短暫的時間中防止對乘員的傷害，必須設置安全裝備，目前主要有安全帶、防撞式車身和安全氣囊防護系統(tǒng)(Supplemental Inflatable Restraint System，簡稱SRS)等。 由于很多事故是難以避免的，因此被動安全性也非常重要，安全氣囊作為被動安全性的研究成果，由于使用方便，效果顯著，造價不高，得到了迅速的發(fā)展和普及。 每年都有數萬人死于交通的事故。主要原因有：酒后或服用某些藥物后駕車，駕車時注意力不集中，疲勞駕車，冒險駕車，或遭遇道路突發(fā)事件如下雪、坑洼和橫穿道路的動物等。 1歷史 汽車發(fā)明之后，當1771 年尼古拉斯?約瑟夫?卡格諾的蒸汽動力汽車Fardier 撞墻時，汽車安全性幾乎立即就成為一個問題。最早的記錄是布理奇特?德利克爾1896 年8 月17日發(fā)生在倫敦的車禍。 美國國會在 1966 年10 月15 日成立了美國交通部(DOT)，目的之一是解決汽車安全問題。1967 年4 月1 日，全國交通安全委員會(NTSB)作為獨立機構成立了，在行政和經費方面隸屬于DOT。然而到1975 年，根據獨立安全委員會條例該機構完全獨立出來。NTSB和在歐洲與其同等作用的機構Euro NCAP(歐洲新車評估組織)發(fā)布了對所有新車的權威安全測試。 2004 年6 月，NTSB 發(fā)布了對新車或SUV 車進行側翻風險測試的新的測試方法。僅有馬自達RX—8 獲得5 星級。然而官方的碰撞試驗結果與汽車在道路上的傷亡并不確切相關。另一種評估汽車安全的方法是研究基于事故原型得到的道路事故統(tǒng)計資料。 盡管汽車的技術先進，但是車禍的傷亡率仍然很高：在美國每年約40 000 人死亡。雖然隨著人口的上升和旅游的增加，這個數字每年在直線上升，而按人口數和按每車行駛里數的事故率卻下降了。1996 年美國每10 000 輛機動車就有2 例死亡事故，德國1.9 例，法國2.6 例，英國1.5 例。1998 年英國有3421 例致命事故，是自1926 年以來最少的一年。還有更多的事故導致終身殘疾。 作為交通參與者的人在可能導致意外的事故方面起著重要作用。說明了與事故的發(fā)生有關的各群體的相關度。主要的一組人是汽車的乘客。有資料指出司機應對80%以上的事故負責。 2孕婦 懷孕的婦女要恰當地使用安全帶和氣囊。密歇根大學的一項研究發(fā)現對孕婦不束縛或不正確的束縛導致胎兒異常的可能性是正確使用束縛的孕婦的5.7 倍。如果安全帶不夠長，可以到汽車廠家或汽車配件供貨商處延長。 3兒童 由于汽車安全裝置一般是為正常身材的成年人設計的，所以汽車安全裝置對于幼兒而言尤為關鍵。實際上一些能保護成人的安全裝置對孩子造成的傷害可能比沒有這些裝置更大。所有12 歲及12 歲以下的孩子應坐在后座，特別是當前座有安全氣囊時，因為安全氣囊的設計只保護成年人但卻可能傷害孩子。兒童安全鎖防止兒童在車門沒上鎖時從車內意外打開車門。車門解鎖后，也只能從車外打開。 3.1 嬰兒 新生兒在體重達到 20 或22 磅(10 或11 公斤)前應放在車輛座椅中。這種座椅設計成放置在后座并面向車尾，從而使嬰兒的臉朝向后窗。有些這種座椅可以雙向安裝的，用于大一點的孩子時可以面向車前。對于嬰兒只能夠面內車尾。安全帶應該在肩部或低于肩。后向嬰兒座椅決不能放在有前排乘客安全氣囊的前座上。后向嬰兒座椅會使嬰兒的頭部靠近安全氣囊艙，如果安全氣囊打開會導致頭部嚴重受傷或致死?，F代的汽車有一個開關可以關閉前排乘客的安全氣囊，這種情況下還必須裝一個固定孩子的座椅。 3.2 蹣跚學步的孩子 年齡在 1 歲以上、體重在20 到40 磅(10 到20 公斤)之間的蹣跚學步的孩子應坐在面向車前放置或反過來放在后座的兒童座椅中。安全帶應該在肩部或低于肩部。 3.3 幼童 年齡在 8 歲以下、體重不足80 磅(40 公斤)、身高不足4 英尺9 英寸 (1.4 米)的孩子建議使用可固定安全帶的幼兒加高座椅，這種座椅可以把兒童升高到一定高度以使座椅安全帶能有效地發(fā)揮作用。這種座椅正向放置，且必須使用膝肩安全帶。確保膝部安全帶較低和較緊的橫過膝部/大腿上，而肩膀安全帶則舒適的通過胸、肩，避免腹部受傷。主要有兩種幼兒加高座椅。如果車的后座低于孩子的耳朵，使用高靠背幼兒加高座椅以保護孩子的頭和脖子。否則，使用無靠背幼兒加高座椅。 4安全裝備 4.1 避免事故的裝備為使駕駛更安全，防止發(fā)生事故，汽車應具有以下的主動安全裝備： （1）轉向信號燈和剎車燈，包括中央高位剎車燈(CHMSL)。 (2)具有電子制動力分配裝置(EBV)的防抱死制動系統(tǒng)(ABS)，防止制動時剎車鎖死而失去牽引。這可以縮短幾乎是各種情況下的剎車距離。參見電子控制剎車輔助系統(tǒng)(EBA) (3)電子穩(wěn)定性控制：當汽車偵測(感覺)到有可能失控時，該系統(tǒng)會使用各種傳感器進行干預。車上的計算機會降低發(fā)動機的動力，甚至使用制動器避免轉向不足或轉向過度。 (4)驅動力控制系統(tǒng)(TCS)。 (5)電子穩(wěn)定程序(ESP)或電子穩(wěn)定性控制(ESC)：具有加速防滑系統(tǒng)(ASR)和電子差速鎖(EDL)。 (6)車道偏離警示系統(tǒng)(LDWS)。 (7)方向頭燈， (8)降低汽車重心以及其他傳統(tǒng)的提高汽車操控性和制動性能的裝備。 4.2損失的控制 事故即將發(fā)生時，各種被動安全系統(tǒng)一起工作以使產生的損失最小。對碰撞試驗中的假人進行的大量研究以使現代汽車更安全。最近，汽車設計中已經注意到了人-車碰撞中行人的安全問題。在歐洲一項有爭議的提案是對銷往歐洲的車限定其最小/最大引擎蓋高度。汽車生產商抱怨這項要求限制了設計的多樣化選擇，導致了難看的外形。另一些人指出在這些事故中，行人醉酒的比率值得注意。自2006 年起，將不允許在四輪驅動汽車和SUV前端裝飾鐵條架。 (1)安全帶避免人被拋向車前端或拋出車外。福特推出了充氣式后排安全帶上2011福特探索者。想想這些氣囊和安全帶之間的交叉。福特汽車表示，它設計的充氣式安全帶減少后座乘客頭部、頸部和胸部受傷，經常是孩子和老人，誰能更容易受到傷害。安全帶已經加入其他福特汽車如Flex和林肯的陣容。 (2)前座安全氣囊在中速正面碰撞中打開以緩沖乘客頭部與儀表板或方向盤的撞擊。 (3)側安全氣囊在側面碰撞時打開以緩沖乘客身體受到的沖擊。 (4)窗簾式氣囊在側面碰撞時保護乘客的頭部。 (5) 膝部氣囊：這個小氣囊的設計是為了盡量減少受傷的下肢為他們使儀表板接觸。膝部氣囊位于坑、下駕駛員側的轉向柱和手套箱上下乘客側。福特推出了一個新的乘客膝部氣囊設計上2015福特野馬。而不是使用傳統(tǒng)的織物設計，這種新的氣囊由充氣，塑料內膽，楔形的內部和外部的手套箱門板之間。在發(fā)生事故時，打氣筒充滿膀胱，伸向前排乘客的腿部整個手套箱，車門外板，福特說。一旦部署，外面的門有助于提供緩沖中的方式類似于傳統(tǒng)的膝部氣囊。新的設計比為乘客的腿部空間上更系統(tǒng)和結果輕百分之65。 (6)保險杠能夠抵擋低速碰撞而不損壞車身。 (7)緩沖潰縮區(qū)(或吸能緩沖區(qū))在汽車與物體相撞時吸收撞擊產生的能量。 (8)碰撞協(xié)調性通過使汽車重量、緩沖潰縮區(qū)域與結構剛度匹配得到改善。 (9)設計骨架結構以保護乘客。有些賽車具有管狀的防滾架。 (10)加固門構件。 (11)燃油泵的閉鎖裝置切斷氣流防止汽油燃燒。 (12)車輛自重：車輛對車外面的人或物可能造成的損害近似地與其動能成正比，該動能等于車重量乘以速度的平方。 4.3新技術 在不久的將來，會有更多的主動安全技術發(fā)展，比如預碰撞系統(tǒng)和車道偏離警告，防止事故的發(fā)生，而不是被動安全，如安全氣囊和汽車撞擊緩沖區(qū)，減少傷害事故中。傳感器、處理和“線”先進技術在過去的幾年里發(fā)展很快這讓制造商開發(fā)出各種各樣的高級駕駛輔助功能，提高碰撞避免或緩解。