姚念奎 王成波 白春玉 陳熠 楊強(qiáng)
摘要:在彈射型艦載機(jī)牽制就位之前,彈射桿觸發(fā)緩沖鉤產(chǎn)生沖擊載荷。相關(guān)構(gòu)件應(yīng)能承受該載荷而不喪失功能或發(fā)生結(jié)構(gòu)破壞?;诰植孔冃渭澳芰渴睾阍?,本文對(duì)此問題進(jìn)行了理論分析,提出了一種計(jì)算沖擊載荷的方法,并通過試飛實(shí)測(cè)數(shù)據(jù)驗(yàn)證了算法的合理性。本研究可為機(jī)/艦結(jié)構(gòu)抗沖擊設(shè)計(jì)提供參考。
關(guān)鍵詞:沖擊載荷;艦載機(jī);彈射桿;航空母艦;緩沖鉤;能量守恒
中圖分類號(hào):V215文獻(xiàn)標(biāo)識(shí)碼:ADOI:10.19452/j.issn1007-5453.2022.01.004
彈射型固定翼艦載機(jī)進(jìn)入飛行甲板的起飛初始站位,在與滑軌往復(fù)車嚙合之前,需要利用彈射桿觸發(fā)母艦牽制系統(tǒng)的緩沖鉤,使之翻轉(zhuǎn)上翹,即由復(fù)位狀態(tài)變?yōu)榇龂Ш蠣顟B(tài),以便于飛機(jī)牽制桿與母艦緩沖鉤的成功嚙合[1-2]。在觸發(fā)過程中,彈射桿和緩沖鉤之間將產(chǎn)生一個(gè)瞬態(tài)沖擊載荷,可能對(duì)相關(guān)構(gòu)件造成斷裂、變形、磨損、失穩(wěn)或疲勞等多種形式的沖擊失效,特別是在飛機(jī)進(jìn)入速度過快的情況下。因此,對(duì)這類沖擊情況進(jìn)行載荷定量分析,對(duì)于研究上述失效行為非常必要[3-4]。另外,機(jī)、艦雙方在進(jìn)行各自功能構(gòu)件的結(jié)構(gòu)設(shè)計(jì)時(shí),同樣需要了解彈射桿與緩沖鉤的沖擊載荷,從而將其作為一項(xiàng)重要的設(shè)計(jì)輸入?yún)?shù),進(jìn)行構(gòu)件材料選擇、零件應(yīng)力/變形計(jì)算、機(jī)構(gòu)運(yùn)動(dòng)仿真和系統(tǒng)動(dòng)態(tài)響應(yīng)分析。由于問題的專業(yè)性和特殊性,目前國(guó)內(nèi)外關(guān)于該類沖擊載荷算法的相關(guān)研究較少,是亟待填補(bǔ)的技術(shù)空白。
1基本原理
艦載機(jī)彈射桿和航空母艦緩沖鉤的沖擊如圖1所示,可視為兩個(gè)彈性體的碰撞問題。利用彈性體變形勢(shì)能等于碰撞動(dòng)能損失的原理,可建立最大沖擊載荷的算法。實(shí)際上,緩沖鉤在母艦彈射滑軌導(dǎo)入槽的安裝座處還設(shè)有緩沖阻尼彈簧,但緩沖鉤本體結(jié)構(gòu)剛度遠(yuǎn)遠(yuǎn)大于該彈簧的勁度系數(shù)。因此,在沖擊載荷計(jì)算時(shí),緩沖阻尼彈簧的影響可以忽略不計(jì)。
沖擊載荷實(shí)際上是接觸區(qū)域的內(nèi)力[5],在瞬態(tài)沖擊情況下,作為平衡沖擊載荷F的彈射桿軸力集度qb呈定常均布,而緩沖鉤剪力集度qh則呈三角形分布[6-7]。由此,建立簡(jiǎn)化彈性碰撞載荷計(jì)算模型,如圖2所示。
由圖2可知,彈射桿與緩沖鉤的線性載荷集度分別為:
4試飛數(shù)據(jù)對(duì)比
某型艦載機(jī)在陸基試驗(yàn)場(chǎng)進(jìn)行正常彈射起飛訓(xùn)練時(shí),對(duì)采集的彈射桿軸力測(cè)量貼片的壓應(yīng)變數(shù)據(jù)進(jìn)行回歸處理[11],共篩選獲得4次彈射桿與緩沖鉤沖擊載荷的有效結(jié)果。按飛機(jī)滑行速度升序排列,將其與本文計(jì)算方法得出的理論數(shù)據(jù)進(jìn)行對(duì)比分析,誤差見表2。
由表2可見,利用本文方法得出的理論計(jì)算值與試飛實(shí)測(cè)值的符合性較好,特別是在較低水平速度的情況下。但是,由于彈射桿與緩沖鉤的沖擊載荷很容易受到其他擾動(dòng)因素的影響,如機(jī)體振蕩、偏心偏航、水平突風(fēng)、推力波動(dòng)等,在航空母艦上操作時(shí)還要受到甲板運(yùn)動(dòng)的影響[12-14]。另外,試飛實(shí)測(cè)數(shù)據(jù)在測(cè)試方法、采樣率和處理方式(主要是濾波處理方式)等方面存在局限性,上述諸因素使得沖擊載荷實(shí)測(cè)結(jié)果呈現(xiàn)一定程度的隨機(jī)性和離散性。
5結(jié)論
在航空母艦上服役的艦載機(jī),其機(jī)體結(jié)構(gòu)通常要遭遇比陸基飛機(jī)更為苛刻的沖擊載荷使用環(huán)境,如典型的彈射沖擊、著艦沖擊和攔阻沖擊等。此類沖擊的共性特征是載荷峰值高、作用時(shí)間短、加載速率快。從飛機(jī)結(jié)構(gòu)動(dòng)強(qiáng)度和沖擊疲勞強(qiáng)度領(lǐng)域的研究角度來看,上述沖擊情況均屬于亟待攻克的現(xiàn)實(shí)技術(shù)難題,同時(shí)也是新型號(hào)研制階段面臨的設(shè)計(jì)障礙[15]。本文從解決飛機(jī)彈射桿與母艦緩沖鉤沖擊載荷問題入手,在理論算法方面取得了技術(shù)突破,并得出如下結(jié)論:
(1)本文基于能量守恒原理及局部彈性變形條件,建立了適用飛機(jī)彈射桿與母艦緩沖鉤的沖擊載荷計(jì)算方法;與試飛實(shí)測(cè)數(shù)據(jù)的對(duì)比結(jié)果表明,其精度滿足工程應(yīng)用,可為機(jī)/艦相關(guān)起降結(jié)構(gòu)設(shè)計(jì)提供載荷輸入,也可用于飛行前快速、有效地預(yù)判沖擊載荷。
(2)沖擊載荷精確的解析算法極為復(fù)雜,除了本文算法涉及的各項(xiàng)參數(shù)外,還與具體研究工況的邊界條件、動(dòng)態(tài)材料屬性、結(jié)構(gòu)尺寸效應(yīng)密切相關(guān)[16],也可能受到意外擾動(dòng)因素的影響。因此,在應(yīng)用本算法進(jìn)行結(jié)構(gòu)設(shè)計(jì)時(shí),須考慮適當(dāng)?shù)妮d荷不確定系數(shù)。
(3)本文算法可拓展應(yīng)用其他艦載機(jī)起降系統(tǒng)結(jié)構(gòu)與母艦設(shè)施的撞擊情況,如攔阻鉤與甲板凸起物的碰撞、艦面保障設(shè)備與飛機(jī)接口的碰撞。應(yīng)當(dāng)指出的是,本算法不適用材質(zhì)差異比較懸殊的碰撞問題,如飛機(jī)輪胎與甲板障礙物的碰撞、飛濺的跑道碎石與飛機(jī)蒙皮的撞擊、鳥與風(fēng)擋玻璃的碰撞等。
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Impact Load Calculation Between Aircraft Launch Bar and Carrier Buffer Hook
Yao Niankui1,Wang Chengbo1,Bai Chunyu2,Chen Yi2,Yang Qiang2
1. AVIC Shenyang Aircraft Design and Research Institute,Shenyang 110035,China
2. Aircraft Strength Research Institute of China,Xi’an 710065,China
Abstract: Before catapulting-style carrier-based aircraft is tracked into the holdback engagement fitting, the launch bar will trigger the buffer hook of the deck hardware at limited speed,which will cause a impact load. The structural components involved must withstand the impact load without malfunction or structural fail. Based on effect of local deformations and law of conservation of energy, the paper analyzes the problem theoretically, and then presents a resolving method about the impact load. The flight test results confirm that it is feasible to use the algorithm to resolve the impact load problem between launch bar and buffer hook. This study can provide useful reference for aircraft/ carrier structures anti-impact design.
Key Words: impact load; carrier-based aircraft; launch bar; carrier; buffer hook; conservation of energy
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