1. Calculation Conditions ( 計(jì)算條件) Contact angle(接觸角度): 10o Frame Size(防沖板尺寸 寬 x 長(zhǎng) x 厚) : 2000B x 2000L x 180H
2. Calculation of Sectional Force (局部力的計(jì)算方式) Among sectional forces, Bend Moment M becomes maximum just before a vessel contact to the board (M max). Thus M max and S max ( maximum sectional force) under M max could be calculated shown below (在局部力之中,就在船只接觸護(hù)板同時(shí)彎曲矩 M 變成最大 (M最大)。因此在M最大 下的M最大 和 S最大 (最大局部力)應(yīng)按以下方式計(jì)算 2.1 Maximum Bend Moment ( M max) 最大彎曲矩 (M最大) Provided a vessel contacts a board at angle of 10 degrees horizontally, the board is considered to be a beam regarding a rubber parts as a spring and a chain attachment position as a fulcrum. Thus, bend moment could be calculated. (假設(shè)船只以10度角接觸護(hù)板,而護(hù)板可認(rèn)作是一個(gè)橫梁, 橡膠部分認(rèn)作是彈簧,鏈條部分的位置作為支點(diǎn),則彎曲矩可如下計(jì)算)
LOAD R 2 from vessel Compression amount of rubber δ (來自船只的加載R2) (橡膠的壓縮量)
Vessel board (船只) (護(hù)板)
Load F from rubber Load R1 from chain (來自橡膠的加載) (來自鏈條的加載)
Chain (鏈條)
Picture 1. Calculation Model for Bend Moment (圖1:彎曲矩的計(jì)算模型)
Max bend moment (M max) could be calculated by the following process because it generates just before a vessel contact the board. 因?yàn)橹挥挟?dāng)船只接觸護(hù)板時(shí)才可產(chǎn)生最大彎曲矩 (M最大),所以它可以按下列程序計(jì)算
That is, Load F = 754kN (就是說橡膠的加載F = 754kN) Accordingly, by putting L = (1000+1000) = 2000mm L1 = 1000mm; L2= 1000mm 據(jù)此, L = (1000+1000) = 2000mm L1 = 1000mm; L2= 1000mm
M max = 754 x 1000 x 1000 x 1000/2000 = 4.11 x 108N·mm 2.2 Maximum Shearing Power ( S max) (最大剪切力)
It generates in a chain attachment position, and the power becomes equal to the load which acts on a chain exactly. That is, Smax = 377kN (它產(chǎn)生于鏈條附件位置,該剪切力等同于作用于鏈條上的加載)
3. Stress Examination (應(yīng)力測(cè)定) 3.1 Cross-sectional form for M max is as follows: (M最大 的橫截面形式如下:) At first, the cross-sectional second moment of this section and the cross-sectional coefficient Z are calculated. (首先計(jì)算本部分的橫截面的第二力矩和橫截面系數(shù)Z) Cross-sectional second moment I = 4.11 x 108 (橫截面的第二力矩) Cross-sectional coefficient Z = 3.6 x 106 (橫截面系數(shù)Z) Thus, bending stress σ= M max/Z = 4.11 x 108/3.6 x 106 (因此彎曲應(yīng)力) = 114N/mm2 < SS400 acceptable stressσa = 140N/mm2 Therefore, it can be said enough safe. (因此可以說是足夠的安全)
Picture 2. Cross-sectional form of the perpendicular direction (圖2:垂直方向的橫截面形式) 3.2 Cross-sectional stressЧ for S max can be considered to be taken by wave and calculated as follows: (針對(duì)S最大橫截面應(yīng)力可認(rèn)為從波狀運(yùn)動(dòng)中獲取并計(jì)算如下)
Cross-sectional stress Ч = S max/Aw 橫截面應(yīng)力 Aw: cross section area of wave ( = 11200mm2) (Aw:波狀運(yùn)動(dòng)的橫截面區(qū)域 Ч = 377 x 1000/11200 = 33.66N·mm2 < SS 400 acceptable stressσa = 80N/mm2 Therefore, it can be said enough safe. (因此可以說是足夠的安全)
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