【導(dǎo)讀】些由起落架故障引發(fā)的事故。然后介紹了下CATIAV5的特點(diǎn)、應(yīng)用、基本操作、各種工。作界面、零部件設(shè)計(jì)、裝配設(shè)計(jì)、運(yùn)動(dòng)仿真、及較高層次的應(yīng)用。在進(jìn)行三維建模之前，首先，從一些官方數(shù)據(jù)上確定起落架的類型，以及一些基本的數(shù)據(jù)。然后進(jìn)行簡(jiǎn)化，省略。扭力臂和機(jī)輪等部分。確定每一部分的具體數(shù)據(jù)，連接形式，以及運(yùn)動(dòng)方式。工作臺(tái)入手，對(duì)各個(gè)部分進(jìn)行零部件設(shè)計(jì)及建模，并且展示出建模步驟。導(dǎo)入裝配設(shè)計(jì)工作臺(tái)，進(jìn)行組裝，添加結(jié)構(gòu)約束。下一步對(duì)組裝好的部件進(jìn)行接合，進(jìn)行。數(shù)字樣機(jī)收放演示。在本文的最后，總結(jié)各種不足和待改進(jìn)之處，并且對(duì)CATIA建模的優(yōu)。缺點(diǎn)進(jìn)行總結(jié)及展望。

　　

【正文】 , which fall away after takeoff and drop to earth。 the aircraft then relies 基于 CATIA 的 大型飛機(jī)起落架建模與分析 10 on titanium skids on the wingtips for landing Figure 26 Takeoff dolly Figure 27 Aircraft U2 Some main gear struts on World War II aircraft, in order to allow a singleleg main gear to more efficiently store the wheel within either the wing or an engine nacelle, rotated the single gear strut through a 90176。 angle during the rearwardsretraction sequence to allow the main wheel to rest flat above the lower end of the main gear strut, or flush within the wing, when fully retracted. Examples are the Curtiss P40, Vought F4U Corsair, Grumman F6F Hellcat, Messerschmitt Me 210 and Junkers Ju 88. The Aero Commander family of twinengined business aircraft also shares this feature on the main gears, which retract aft into the ends of the engine nacelles. The rearwardretracting nosewheel strut on the Heinkel He 219 and the forwardretracting nose gear strut on the later Cessna Skymaster similarly rotated 90 degrees as they retracted. On most World War II singleengined fighter aircraft (and even one German heavy bomber design) with sideways retracting main gear, the main gear that retracted into the wings was meant to be raked forward, towards the aircraft39。s nose in the down position for better ground handling, with a retracted position that placed the main wheels at some angle behind the main 中國民航飛行學(xué)院航空工程學(xué)院畢業(yè)論文 11 gear39。s attachment point to the airframe this led to a plex geometry for setting up the angles for the retraction mechanism39。s axis of rotation, with some aircraft, like the P47(Figure 28) Thunderbolt, even mandating that the main gear struts lengthen as they were extended down from the wings to assure proper ground clearance for its large fourbladed propeller. One exception to the need for this plexity in many WW II fighter aircraft was Japan39。s famous Zero fighter, whose main gear stayed at a perpendicular angle to the centreline of the aircraft when extended, as seen from the side. Figure 28 A Royal Air Force P47 A multiple tandem layout was used on some military jet aircraft during the 1950s, pioneered by the Martin XB51, and later used on such aircraft as the U2, Yakovlev Yak25, Yak28 and the B47 Stratojet because it allows room for a large internal bay between the main wheels. A variation of the multi tandem layout is also used on the B52 Stratofortress which has four main wheel bogies (two forward and two aft) underneath the fuselage and a small outrigger wheel supporting each wingtip. The B5239。s landing gear is also unique in that all four pairs of main wheels can be steered. This allows the landing gear to line up with the runway and thus makes crosswind landings easier (using a technique called crab landing). The challenge of designing a tandemgear layout is that the aircraft has to sit (on the ground) at the optimum flight angle for landing when the plane is nearly in a stalled attitude just before touchdown, both fore and aft wheels must be ready to contact the runway. Otherwise there will be a vicious jolt as the higher wheel falls to the runway at the stall. 基于 CATIA 的 大型飛機(jī)起落架建模與分析 12 Figure 29 B36 Peacemaker One very early undercarriage arrangement that passively allowed for castoring during crosswind landings, unlike the active arrangement on the B52, was pioneered on the Bleriot VIII design of 1908. It was later used in the much more famous Bl233。riot XI Channelcrossing aircraft of 1909 and also copied in the earliest examples of the Etrich Taube. In this arrangement the main landing gear39。s shock absorption was taken up by a vertically sliding bungee cordsprung upper member. The vertical post along which the upper member slid to take landing shocks also had its lower end as the rotation point for the forward end of the main wheel39。s suspension fork, allowing the main gear to pivot on moderate crosswind landings. Landing gear and accidents Malfunctions or human errors related to retractable landing gear have been the cause of numerous accidents and incidents throughout aviation history. Distraction and preoccupation during the landing sequence played a prominent role in the approximately 100 gearup landing incidents that occurred each year in the United States between 1998 and 2020. A gearup landing incident, also known as a belly landing, is an accident that may result from the pilot simply fetting, or failing, to lower the landing gear before landing or a mechanical malfunction that does not allow the landing gear to be lowered. Although rarely fatal, a gearup landing is very expensive, as it causes massive airframe damage. For propeller driven aircraft it almost always requires a plete rebuild of engines because the propellers strike the ground and suffer a sudden stoppage if they are running during the impact. Many aircraft between the wars at the 中國民航飛行學(xué)院航空工程學(xué)院畢業(yè)論文 13 time when retractable gear was being monplace were deliberately designed to allow the bottom of the wheels to protrude below the fuselage even when retracted to reduce the damage caused if the pilot fot to extend the landing gear or in case the plane was shot down and forced to crashland. Examples include the Avro Anson, Boeing B17 Flying Fortress and the Douglas DC3. The modernday FairchildRepublic A10 Thunderbolt II carries on this legacy. Some aircraft have a stiffened fuselage bottom or added firm structures, designed to minimise structural damage in a wheelsup landing. When the Cessna Skymaster was converted for a military spotting role, fiberglass railings were added to the length of the fuselage. The Bombardier Dash 8 is notorious for its landing gear problems. There were three incidents involved, all of them involving Scandinavian Airlines, flights S