1500米海洋探矿绞车主传动系统设计【说明书+CAD+SOLIDWORKS】
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Computational and experimental analysis of trawl winchesbarrels deformationsVladimir Solovyova, Alexandr Cherniavskyb,aKamchatka Polytechnic College, 37 Leningradskaya St., Petropavlovsk-Kamchatsky 683003, RussiabSouth-Ural State University, Applied Mechanics Dept., 76 Lenin Ave., Chelyabinsk 454080, Russiaa r t i c l ei n f oArticle history:Received 10 May 2012Accepted 8 October 2012Available online 2 November 2012Keywords:Trawl winchStrengthDurabilityRope tension gaugea b s t r a c tThe necessary use of heavy duty trawl winches can cause plastic deformation of winch bar-rels, known as rolling. Numerical analysis shows that the main reason for such deforma-tion is pressure from layers of cable, while other reasons a rolling spot of stress near therope-barrel contact point, barrel bending and torsion play a small role. The influence ofdifferent factors (barrel sizes, material properties, rope properties, and load levels) on thestrain accumulation rate is analyzed. The described method provides a barrel design fornew winches and load constraints for existing winches. New rope tension gauge and spe-cial software are developed to help the trawler master predicts situation that can lead tobarrel plastic deformation.? 2012 Elsevier Ltd. All rights reserved.1. IntroductionIndustrial fishing requires increasing trawling speed and depth. Depths of 600800 m are often necessary, and some sea-food catch demands depths up to 2000 m. Desired trawling speed increases from, for example, 46 knots (about 11 km/h).Increased hydrodynamic resistance and weight of trawling systems produce heavy loads on deck machinery, forcing it towork at the limits of its capacity.One of the critical pieces of equipment on a trawler is the winch barrel. These barrels are quite large, holding up to 3 km ofrope with a 2530 mm diameter, so a deformed barrel cannot be repaired or changed out at sea. Despite some design andtechnological differences, all examined barrels (of Russian-built winches LETR 23 and LETR 25, Polish WTJ-12.5, etc.) canbe reduced to a single scheme. Fig. 1 shows a barrel of WTJ-12.5 winch with a 12.5 ton pulling force installed on a trawler-freezer of 5500 tons displacement. The barrel consists of a spindle (a pipe with an outer diameter of 495 mm and inner of420 mm) and two flanges. Cyclic loading caused by trawling and trawler hoisting leads to increasing barrel deformation withthe number of cycles. Suchdeformation,shown schematically in Fig.1 by the dotted line,results in contactwith the barrel andsurrounding structures (brake, supports, etc.), destruction of the barrel bearings, and cracks between the barrel spindle andflanges. Warping was observed on all of Kamchatkas fishing vessels, demanding repair (or replacement) of the barrel aboutevery year to prevent contact and fracture of brake, bearings, etc., about 10% of necessary barrel repairs are for cracking.2. Calculations and resultsRope tension causes torsion and bending of the barrel spindle. The bending is at maximum when the rope is at the middleof the spindle length. Mechanical stresses related to this bending and torsion vary cyclically in any barrels point due to the1350-6307/$ - see front matter ? 2012 Elsevier Ltd. All rights reserved./10.1016/j.engfailanal.2012.10.007Corresponding author. Tel./fax: +7 351 2679306.E-mail address: a.o.chermail.ru (A. Cherniavsky).Engineering Failure Analysis 28 (2013) 160165Contents lists available at SciVerse ScienceDirectEngineering Failure Analysisjournal homepage: /locate/engfailanalbarrel rotation and the fact that the brake and gear clutch driving the barrel are located on its opposing sides (Fig. 1). Besidesthis, additional stresses due to contact interaction of the rope and barrel can be expected: peak stresses form in relativelysmall contact spots near the contact point and stresses produced by uniform pressure of rope wound under tension(the entire coil can contain up to 25 rope layers). Numerical estimation of stresses and strength given below are made fora 12.5-ton winch made of steel with 216 MPa yield stress and an ultimate strength of 432 MPa.Simple estimations performed by well-known strength-of-materials formulas (see, for example 1) show that maximumbending stresses do not exceed 18 MPa, so the bending cannot be the main source of plastic deformation. The same can besaid about torsion, which produces about 5 MPa.Contact stresses calculation is much harder and demands usage of numerical analysis. The danger of these types of stres-ses is connected with the motion of the contact spot in the circumferential direction due to rotation of the barrel and in theaxial direction due to the gradual filling of the barrel with the rope; such motion could cause plastic deformation of the bar-rel upon rolling if stresses are great enough. The numerical model consisted of the barrel, layers of wrapped rope and therope piece under load (Fig. 2). These were investigated with the aid of finite-element analysis. The barrel was treated as alinear elastic isotropic body and the rope as a linear-elastic anisotropic. Elastic modulus of steel rope in the axial directionwas chosen on the basis of measured elongation under a workload (1% elongation was used; experimental results in 2,3give values of 0.41.6%); elastic modulus in the transverse direction was taken up 510 times lower than in the axial direc-tion. The exact value of this quantity has little effect on the calculation results. Wrapped layers of rope were modeled by anelastic solid cylinder with appropriate anisotropy. ANSYS finite-element code was used for calculations.Calculated stresses appear surprisingly small not greater than 5 MPa, mainly due to relatively little stiffness of thewound rope compared to a steel barrel (note that in accordance to the winch manual, at least two wound layers mustbe kept on the barrel). Therefore, the influence of these stresses on barrel deformation cannot be noticeable.The main source of high stress and plastic deformation in this case is pressure on the barrel from layers of pre-stretchedrope. In the computational sense this task is analogous to the problem of uneven heating where pre-tension of the rope ismodeled by thermal shrinkage. This shrinkage varies from layer to layer because shorter trawl rope in water has lesshydraulic resistance and weight, so during trawl hoisting the rope traction decreases up to 23 times 4. Thus, the compu-barrel axle bearing brake 2500 1600 deformed shape gear clutch torque from engineFig. 1. Barrel and its deformation scheme.Fig. 2. Computer model of rope wound layers spindle and stress distribution in spindle (darker shading corresponds to higher stresses).V. Solovyov, A. Cherniavsky/Engineering Failure Analysis 28 (2013) 160165161tational scheme is a two-layer cylinder: the inner one is a steel barrel while the outer is wound rope cooled to imitatepre-stress conditions. Cooling was calculated on the basis of maximum pulled force taken from the winch manual and exper-imental data 4 on decreasing this force in trawl hoisting.Assuming both barrel and rope are perfectly elastic, this task can be solved analytically on the basis of known Lame solu-tion (see, for example 5). Fig. 3 shows results of the solution: as soon as after winding six layers with maximum winchnameplate momentum, some plastic deformation must appear.Subsequent elasticplastic analysis cannot be fulfilled analytically and ANSYS software was again used for the numericalsolution. The main feature of the systems behavior is that high stresses do not mean immediate fracture; even a small de-crease in the barrel radius due to plastic deformation reduces pressure produced by the rope; corresponding reduction ofstresses stop plastic deformation when pressure and barrel resistance are balanced. In subsequent cycles the rope is woundon an already reduced barrel, but pulling force and thus pre-tension is independent of the barrel radius. In elastic short-ening of the barrel radius and connected elongation of its axial length are restricted in one cycle of trawl hoisting. However,such changes would accumulate with the number of cycles. Fig. 4 shows an example of calculated elongation of the barrelwith cycle numbers. Stabilization after some cycles occurs if deformation strengthening of barrel material is great enough,i.e. if the ultimate strength of the material is appropriately high.Calculated results were checked using deformation measuring on barrels of trawl winches WTJ-12.5, submitted for repairto the shipyard of Petropavlosk-Kamchatsky from February to June 2010. Barrel elongation, which demands replacement, isat about 20 mm. Investigation of winches in repair show that the distance increases between the outer points of the barrelflanges is higher than elongation of the inner part of the barrel (about 1.5 times) because of the flanges bending see Fig. 1.There were some cases of cracks between the barrel and flanges.Deformation differences between barrels are quite high, the main reason seemingly being the absence of accurate loadfixation during winch exploitation. Moreover, the shrinkage of the barrel is neither strictly axisymmetric nor symmetric withrespect to barrel mid-plane (two barrel measurement results are represented in Fig. 5 by thin lines; segments shows max-imum deviation from symmetry). However, in the middle part of the barrels calculated radius decrease is near to the mea-sured ones (the bold solid line on Fig. 5 represents calculations whereas thin lines represent measured barrel profiles).Deviations near the barrel flange are connected with specific loading factors pressure on the flange from the rope wrapthat finishes layer (see Fig. 6). Despite special devices for forming rope layers, the finishing wrap falls into a gap betweenthe preceding wrap and flange, leading to additional force on the flange and bending the barrel. This force and correspondingstress was computed using finite-element analysis (contact tasks capabilities of ANSYS/LS-DYNA in implicit formulations).It is necessary to remember that in different layers of rope these loads are applied to different points. An improved numerical51015 N0 200 eqv, MPa 300 100 yieldFig. 3. The dependence of the maximum equivalent stresses in the barrel on the number of layers of wound cable (analytical solution).l, mm -30 -20 -10 050100 N, cycleFig. 4. Barrel elongation vs. cycle numbers.162V. Solovyov, A. Cherniavsky/Engineering Failure Analysis 28 (2013) 160165model, taking into account these additional loads and stresses, give good agreement with the experiment (bold dotted line inFig. 5). Besides agreement in deformation, the model predicts maximum stresses in just the same points where cracks inused barrels were found.A tested numerical model allows accurate enough estimation of barrel strain accumulation versus the number of cycles asshown in Fig. 4. The main questions about such results are whether the elongation stops after a number of cycles and whatlength increase will be accumulated to this moment. Finite-element calculations are very time-consuming; a more conve-nient way is using the shakedown theory 6,7, which gives a direct way to estimate load-carrying capacity without cy-cle-by-cycle calculations. One advantage of the theory is relatively simple calculations that allow study of thedependence of the accumulated strain (in this case barrel elongation and radius reduction) on the material properties anddimensions of the structure. The disadvantage comparing to cycle-by-cycle calculation is an unknown rate of strain accumu-R, mm-6-4-200.8x, Mcalculated measured corrected calculations xFig. 5. Barrel radius decrease.Fig. 6. Finite-element model of barrel with flange and wound rope (a) and calculated stress distribution (b).E1, GPa0102030lmax, mm E1, GPa0 2 4 l1, mm 20302030 048 200 400 , MPa , %yu(c)(b)(a)Fig. 7. Stressstrain diagram of the barrel material (a), dependence of accumulated strain on these diagrams and rope elastic modulus (b and c).V. Solovyov, A. Cherniavsky/Engineering Failure Analysis 28 (2013) 160165163lation; only strain after numerous cycles can be found, necessary number of cycles remains unknown. This is useful, how-ever, if we try to make a barrel with a sufficiently long lifespan.Omitting calculation details, the solid line on Fig. 7a corresponds to a stressstrain diagram of the material used in theanalyzed barrel. A dotted line gives hypothetic 1.5-times stronger material, and the dashed line indicates two times morestrength. Fig. 2b illustrates calculated elongation of the barrel (using the shakedown approach) after numerous cyclesdepending on rope elasticity E1(higher E1corresponds to stiffer rope); the solid line shows results for present material whilethe dotted and dashed for stronger ones (see Fig. 7a). For comparison, Fig. 7c shows barrel elongation after the first cycle,calculated via finite-element analysis.3. DiscussionCalculation results similar to those shown in Fig. 7b can be used to find barrel material of minimal strength (i.e. the leastexpensive) while providing properly limited elongation. It also proves that surface hardening of the barrel does not help tosolve elongation problem: all material must be equally as strong because of high stresses in the inner (closest to axle) pointsof the barrel. Increasing the barrels wall thickness is also ineffective: if the material remains unchanged, deformations cal-culated for a 25 mm (double) thickness increase are still greater than those demanding repair.It is interesting to compare elongation after the first cycleDl1(Fig. 7c) with elongation after numerous cyclesDlmax(Fig. 7b). The first (Dl1) decreases with increasing stiffness of the rope, while the second (Dlmax), contrarily, increases. Thereason is that maximum pressure that can be produced by stiff rope is greater than by stretched rope, but stiff rope tensiondecreases with deformation of the barrel (radius decrease) faster than of compliant rope. Taking into consideration barreldeformation in every cycle, it is possible to show that stiff rope strain accumulation in the first cycles will be less, but willcontinue during increasing number of cycles. Note that the stiffness of rope increases during operation along with ropeelongation.Calculations like those shown above can be used in winch design (or repair) to choose proper materials for winch barrels.There are cases, however, when barrels are already made from steel insufficiently strong to eliminate strain accumulationunder maximum load. As a palliative, it is possible to offer to constraint maximum load but in some circumstances max-imum load capacity may be sill needed. To help the trawl master to solve this problem, a special combination of hardwareand software was developed 8. It consists of rope tension gauge, software that predicts pressure on the barrel after all ropeis hauled in, and calculations to determine whether the barrel will deform at a given pressure.Rope tension gauges use strain sensors (tensometers) mounted inside the hollow axle of the upper pulley (Fig. 8). Gaugesplaced there are well protected against environmental action (salt water, ice, etc.) and do not disturb the crew during theirwork. Eight sensors with special connection patterns give information about rope tension even in the case of an unknownangle between rope and deck this unknown angle is also computed using the sensor signal. An amplifier and transmittermounted inside the hollow axle transfers the signal in digital form to a receiver in the deckhouse.Software that predicts plastic deformation occurrence does not use only measured rope tension it includes a model fortension calculation taking into account water resistance and the weight of the trawl system and ropes. As well as predictionof plastic deformation, the software solves one more important task: it defines if it is possible to use the trawl at a givendepth and speed with given pulling force providing by the trawler.4. ConclusionNumerical analysis reveals the reason for heavy-duty winch barrel deformation: evenly distributed pressure of woundrope cause plastic strains that covers the whole volume of the barrel material. Running spots of contact stresses nearthe point of contact between the rope and barrel, barrel bending and torsion have less importance. Strain (barrel elongation)rope pulleyaxle gauges amplifier and transmitterFig. 8. Rope tension measuring system.164V. Solovyov, A. Cherniavsky/Engineering Failure A
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