Modelling, Repairing and Upgradationof Test Bench for Recoil MechanismAuthor(s) Ahsan Naseer 14 – ME – 109 Israr Ahmed 14 – ME –112 M. OsamaSaeed 14 – ME– 142 A Final year project submitted inpartial fulfillment of the requirements for the degree ofB.
Sc. Mechanical EngineeringProject Advisor:Dr. Riffat Asim PashaProfessor and Chairman MED NeutralExaminer Signature:_____________________________________________ Project Advisor Signature:_____________________________________________ DEPARTMENT OF MECHANICAL ENGINEERINGFACULTY OF MECHANICAL & AERONAUTICALENGINEERINGUNIVERSITY OF ENGINEERING ANDTECHNOLOGY TAXILAJanuary 2018 AbstractTestBench for Recoil Mechanism The recoil mechanism is an independent hydro pneumatic system.Ahydraulic Recoil Mechanism is a way of limiting the effects of recoil andadding to the accuracy and firepower of an artillery piece. The project dealswith the modelling of test bench for recoil mechanism for the purpose ofrepairing and upgrading it. Through modelling the fault in apparatus can beeasily identified and system can be modified.
The apparatus containelectrohydraulic valves, Hydraulic cylinder, pump and an electric motor whichare highly nonlinear devices. Bond graph is a convenient tool for modellingnonlinear elements. The state space equations are derived using the naturallaws of science and by using bond graph approach.
These nonlinear equationswill then be simulated in some appropriate equation solver software. Simulationwill also be done in 20-Sim software. The response of system will be predictedin terms of graphs and modification will be carried out.Keywords:Recoil mechanism test benchTest bed for recoilModeling and Control of Hydraulic ActuatorUndertaking WE certify thatfinal year project titled “Modelling,Repairing and Upgradation of Test Bench for Recoil Mechanism” is our ownwork. The work has not been presented elsewhere for assessment. Where materialhas been used from other sources it has been properly acknowledged / referred.
Ahsan Naseer Israr Ahmed14 – ME – 109 14- ME – 112 Osama Saeed14 – ME – 142 Acknowledgement Firstof all we are thankful to Allah who gives us the wisdom and resources for thiswork. After than we are thankful to Ex- General Manager, Descom HeavyIndustries Taxila Brig. Dr. Muhamad Adnan Qasim for introducing and leading usto the way of modelling. We are thankful to our Project advisor Dr. Riffat AsimPasha for helping us and equipping us with the books for our knowledge.Appreciation also goes to HIT management for letting us work in their facilityand financially supporting our work.
Contents Abstract 2 Undertaking. 3 Acknowledgement 4 Table of Figures. 6 Abbreviations. 7 1. Introduction. 8 1.1. Problem Statement 8 1.
2. Objectives. 9 2. Description of Internal Mechanism.. 9 3. Modelling.
11 3.1. The Bond Graph (BG) Approach. 11 3.
2. Modelling Description. 12 3.2.
1. Electric Motor 12 3.2.2. Pump. 13 3.2.3.
Hydraulic Cylinder 15 3.2.4. Electro-hydraulic Valve (EHV) 16 3.2.
5. Miscellaneous. 18 3.3. Overall Bond Graph Representation. 18 3.4.
Result in terms of Graph. 19 4. Project Progress. 19 References. 20 Table of Figures Figure 1- Recoil Mechanism Cylinders 8Figure 2- Schematic of Hydraulic System_ 9Figure 3- A permanent Magnetic AC Motor 12Figure 4- DC series Motor and corresponding BG_ 13Figure 5- A Displacement Pump (Schematic) 13Figure 6- Bond Graph Model of Pump_ 14Figure 7- Hydraulic Cylinder 15Figure 8- BG representation of Hydraulic Cylinder 16Figure 9- Internal Passages in an EHV_ 17Figure 10- Bond Graph Behavior 17Figure 11 Bond Graph Representation of entire Model 18Figure 12- Graph b/w Pressure, Velocity and Positionvs Time_ 19 AbbreviationsFinal Year Project FYPUndergraduate UGBond Graph BGElectro-Hydraulic Valve EHVPressure Regulator Valve PRVSpeed Regulator Valve SRVGyrator GYTransformer TFInertia ICompliance CResistance RModulated Resistance MRModulated Transformer MTFModulated Gyrator MGYOne Junction 1Zero Junction 0Chapter # 011.
Introduction1.1. ProblemStatementRecoilmeans the backward motion of the of the gun when we discharge the weapon thisphenomenon is also referred as kickback in technical terms it practicallyapplies the newton’s third law of motion whereas the mechanism carrying out thephenomenon is called recoil mechanism which is basically the core of our study.
The hydraulic recoil mechanism which is used in the artillery in the tanks isof immense important being responsible for giving accuracy to the weapon andreducing the effects created by recoil mechanism thus nullifying any possiblechance of breakage, wreckage of the apparatus. This hydraulic recoil mechanismis tested over the recoil test bench which we eventually tend to repair andupgrade. Figure 1- Recoil Mechanism Cylinders Thehydraulic recoil mechanism test bench comprises of hydraulic, mechanical andelectrical systems in order to provide with the similar exerted pressure whichwe face in the actual recoil mechanism. To know the basic problem we first haveto consider the structure of the recoil test bench, at the back end it has two cylindersone filled with the oil and the other filled with oil and air partially, thelater one comprising of both the oil and the air provides with the reaction andacts as a spring. The purpose of the accommodation of spring-like adjustment isto avoid any possible chances of breakage in the tank gun.Undernormal circumstances the test bench works in appropriate manner and help usprovide familiar conditions to the gun barrel in order to test it but thecertain hydraulic test bench under consideration is out of order thus we firstwere required to identify the problem causing the seizure of the test bench andsorting out the problem in order to repair the test bench, further we tend toupgrade the hydraulic test bench with innovation reducing any chances offurther seizures. As mentioned earlier the test bench comprised of bothelectrical and mechanical systems thus by processing different parts of thetest bench separately we identified the spot creating the problem. The detailsof the operations carried out to identify the problem, solution and upgradationwill be further discussed in later stages.
1.2. ObjectivesTheobjective of this Report is to present work done on entitled project. First Thetest bench will be modelled and state space equations will be derived. Based onthose state space equations the response of the system at any desired time orgiven input can be predicted. Theseequations can be simulated in proper software like 20-sim and graphs are shownat the end of this report.
The system will also be practically checked andrepaired. We proposed to add data acquisition system in the equipment as itsupgradation. It will allow checking the behavior of recoil mechanism betterthan before and storing the information.2. Figure 2- Schematic of Hydraulic System Description of Internal MechanismThe hydraulic systemconsists of following parts:· Oil filter:Oil filter WC37-50is a net filter which is mounted on the oil suction pipe to defend the oilpump.· Vane type oil pump: Vane type oil pumpYB-50 is used for conversion of the mechanical energy transmitted to the motorinto the hydraulic energy which is used as the hydraulic driving force.· Over-flow valve:Mediumpressure over flow valve Y1-63B is used as safety valve on the machine whichlimits the pressure in the hydraulic system to a certain value and protects thehydraulic system from over load. The pressure regulating limits are 3-63Kg/cm^2.
· Cock of the pressure gauge:Cock of the pressure gauge K-1B is a small stop valve which is used for thecut-in and cut-off the oil way.· Speed regulating valve:Speed regulating valve Q-63Bis used for adjusting the speed of the cylinder motion. The adjusting limits offlow rate are 0.06-63 Liter/minute.
· Electro-hydraulic valve:Electro-hydraulic valve 34DY-6382 plays the role of guiding. The flow reversingis controlled with the aid of electromagnetic valve. Speed is adjusted byone-way throttle valve, located in the control oil way and on the hydraulicvalve pod.· Hydraulic Cylinders:Hydraulic Cylinders of type RS06-002 are used to convert the pressure intoforce in order to check the recoil mechanism cylinders.
Ser. No Part No Name Qty Specifications Remarks 1 RS06-002 Oil Cylinder for pulling test 1 D=100 S=700 2 WC37-50 Oil Filter 1 3 YB-50 Vane type oil pump 1 Q=501/min H=63kg/cm^2 4 J02-56-6 Motor 1 N=7.5kw , n=970 r.p.m 5 Y1-63B Over-flow valve (medium pressure) 1 6 K-1B Cock of the pressure guage 1 7 Q-63B Speed Regulating Valve 2 8 34DY-6382 Electro-hydraulic valve 2 9 HS06-601 Oil cylinder for screwing in packing box nut 1 D=100 S=200 10 Y-50 Pressure guage 1 H=1000kg/cm^2 · Chapter # 023. Modelling3.1.
The Bond Graph(BG) ApproachModellingof the whole equipment was done through bond graph technique. Bondgraph, short for the power bond graph, is a graphical approach to deal withmultiple energy categories of engineering system, based on the law ofconservation of energy. The bond graph method was proposed by ProfessorH.M.
Paynter of MIT in 1959 and developed into a modeling theory and method byKarnopp and Rosenberg1. Now bond graph method has been widely usedfor teaching, research and engineering development in universities andengineering in such countries as the United States, the Netherlands, France,Britain, Germany, Canada, India, Japan, Australia, etc.Bond-graphmodelling is a powerful tool for modelling engineering systems, especially whendifferent physical domains (e.g. Mechanical, Electrical and Hydraulics) areinvolved.
Furthermore, bond-graph sub models can be re-used elegantly, becausebond-graph models are non-causal. The sub models can be seen as objects;bond-graph modelling is a form of object-oriented physical systems modelling.Thebond graph generalizes a variety of physical parameters into four kinds ofstate variables, namely effort, flow, momentum and displacement, which canrepresent any physical components in the actual system. Bond consists of thepower bond and the signal bond, of which power bond is commonly used. The powerbond is a line segment, with a half arrow and a short vertical line, is used toconnect bond-graph components.
The half arrow indicates the direction of energyflow and positive power transport, and the short vertical line represents thecausality. The main effect of the causality is to determine the relationshipbetween two bond-graph components, i.e., one is the reason for the powertransmission, and the other is the result of the power transmission. In bondgraph, the e (effort) and f (flow) pair are carried by a single power bond, andtheir product is equal to the power transmitted by this power bond.Thereare nine components in bond graph, they are effort source (Se), flow source(Sf), resistive element (R), capacitive element (C), inertial element (I),transformer (TF), gyrator (GY), “0” junction and “1”junction. We can draw the corresponding block diagram as long as the directionof the power flow and causality between these components are determined. 3.
2. ModellingDescription3.2.1. ElectricMotorCommonly anelectric motor is represented by a gyrator “GY” in bond graph.
Here gyratorconverts Electric current into Torque and Voltages into rotational Speed suchthat the total power of the system remains conserved. Figure 3- A permanent Magnet AC Motor Figure 3- A permanent Magnetic AC Motor The poles shown in above figures creates magnetic fieldwhich is responsible for establishing a relationship between the electricaldomain, which is an input side in E. Motor and the Mechanical Domain which itoutput (i.e. rotation). In case of permanent magnet this field remains constantbut in case of separately excited motor such as Shunt or series motor the fieldis the function of current through which we established magnetic field.
Therefore output aslo becomes function of the input field current. In the givecase a DC series motor is used, separately excited by field current “if”and input current “ia” and input voltage “ea” and ‘ef’is field voltage 3.The equation corresponding tofigure-2 is given. and And ‘ ‘ and ‘ ‘ are torque and rotational speed and ‘ ‘ is transduction coefficient. Figure 4- DC series Motor andcorresponding BG Infigure 4 the ‘I’ before and above ‘MGY’ represents Self Induction, ‘R’ is Resistance and ‘I’ after ‘MGY’ ispolar moment of inertia and ‘R’ is rotating friction loss.3.2.2.
Pump Thepump that is presented for modelling is displacement pump since it is simplerto model than centrifugal or any other rotary pump. Thereare many analogies between rotary electromechanical devices and hydromechanical devices. Just as a dc motor with multiple windings and a commutatorfunctions as a gyrator, a pump with several pistons and a porting arrangementfunctions essentially as a transformer. The field port of a dc motor allowsmodulation of the gyrator parameter, and a stroke control on a pump, if itexists, allows modulation of the transformer ratio. Figure 5- A Displacement Pump(Schematic) Asit is clear from the figure-5 first the rotary motion that is because of therotation of motor is to be transformed into reciprocating motion of Pistonwhich is than further to be transformed into hydraulic pressure. The force uponthe Piston can be easily transformed into pressure that is it is easy to movefrom the reciprocating domain to hydraulic domain.
The relations are given. Here ‘A’ that is area of piston is acting as transformer ratio. ‘F’ isforce of piston, ‘P’ is pressure, ‘V’ is piston velocity and ‘Q’ is hydraulicflow rate. Therefore it can be easily represent by a transformer in bond graph. Nowtake a look at the first step that is to convert the rotary motion intoreciprocating motion. It is rather difficult to understand.
It can be representedby a modulated Transformer in BG model. Here the transformer ratio will be afunction of angle ” “. 1 And 1 For simplification purposes, theequation can be represented in the following form. ?Where, 1 Figure 6- Bond Graph Model ofPump 3.2.
3. HydraulicCylinder Figure 7- Hydraulic Cylinder HydraulicCylinder is device to convert hydraulic pressure of pump into force that isneeded to move the piston of recoil mechanism that is to be attached with thetest bench. It contains ram whose operation and bond graph model is similar tothat was discussed earlier in pump’s second part in which we converted forceinto pressure. Of course here will be the reverse phenomena. Thereforetransformer ‘Tf’ function will be usen in bond graph model. Here in this model,some non-linearity will also be added into our model. These are as given.
1) Internaland External Leakage.2) Friction.3) HydraulicOil Compressibility.4) PistonArea difference (since A1 = A2). This creates forceimbalance.Some of these nonlinearities were also present inPump.
That is friction and internal leakage. Compressibility that is added herewill account whole model.Oil compressibility is given as. 4V0 = Volume of the section.B = Bulkmodulus of oil.
Forinternal and external leakage, the following relationship will be used. Where, Figure 8- BG representation ofHydraulic Cylinder And ‘µ’ is oil viscosity, ‘L’ will be length along leakage, ‘di’is the diameter of piston and ‘rc’ is the radial clearance betweenpiston and cylinder walls.2 The aboverelation that accounts for leakage can also be used in pump. To account forfriction the resistance ‘R’ above force ‘F’ bond is used.
Here the basicrelation will be same as the basic relation for resistor as described above buthere the value of ‘R’ will be changed. 2 Here ‘FF’will be frictional force ‘Vp’ is the velocity of piston and ‘Kv’is the viscous force coefficient. Also here ‘R = Kv’. The samerelation will be used to evaluate force of friction in Pump.3.2.4. Electro-hydraulicValve (EHV) Electro-hydraulicvalve is used to set the direction of cylinder piston.
Therefore it acts as acontroller in equipment. It has a spool valve as shown in figure that sometimesprevent the hydraulic fluid to cross sometimes it allows it to flow it from onedirection and other thereby controlling the whole process. This spool isactuated by solenoid valves, which are placed at its both ends that providedisplacement ‘z’ that controls the flow of oil. There are internal passages inEHV as shown in figure-9. Figure 9- Internal Passages inan EHVEHV provides fourpassages for oil to flow. Its function is similar to Wheatstone bridge. Itsbond graph model will be shown in the end with the whole model.
Figure 10- Bond Graph BehaviorHere flow when non-linear behavior is added. 1 Here ‘Q’ is flow rate, ‘P’ is pressure, ‘Cd’coefficient of discharge and ‘A(z)’ is the area to which flow has to pass. Hereit can be seen that area ‘A(z)’ depends upon the spool displacement ‘z’. Theabove relation is also used for Speed regulator valve (SRV) and PressureRegulator Valve (PRV).
3.2.5. Miscellaneous Thereare some other relations that are used in model. Such as the resistance tohydraulic oil flow is given1. But the condition to use thisrelation is that Reynold number should be less than 2000.
And the hydraulic Inertia is also considered in calculations. In aboverelations ‘ ‘ is density of oil, ‘L’ is the overalllength to which fluid has to approach, ‘ ‘ is fluid viscosity and ‘d’ and ‘A’ arepipe diameter and cross-section.3.3. Overall BondGraph Representation Figure 11 Bond Graph Representation of entire Model 3.
4. Figure 12- Graph b/w Pressure, Velocity and Position vs Time Result in terms of GraphTheabove bond graph representation was simulated and above graph was generatedautomatically only after giving values to all variables and constants. Some ofthe values were known and some are assumed.4.
ProjectProgressGraphicalResults were shown after putting some values. Some of the values to dimensionalvariables that we didn’t know are assumed for right now. A general trend hasbeen shown. This will remain the same but its magnitude can vary after puttingaccurate values to dimensional variables. Moreover Control of the systemremains to be added. State space equations also needed to be derived. Thesystem is now in working condition and upgradation is in progress. References 1Dean C.
Karnopp, Rosenberg, System Dynamics Modelling and Simmulation ofMechatronics System, 5th edition.2B. Sulc, J. A. Jan, Nonlinear modelling and Control of Hydraulic Actuators,Vol. 42, No.
3/20023Nayana P. Mahajan, Dr. S.
B. Deshpande, Study of the nonlinear behavior of DCMotor using Modelling and Simmulation, International Journal of Scientific andResearch Publications, Volume 3, Issue 3, March 20134Jun Yan, Bo Li, Hai-Feng Ling, Hai-Song Chen, and Mei-Jun Zhang, NonlinearState Space Modeling and System Identification for Electrohydraulic Control,Hindawi Publishing Corporation, Mathematical Problems in Engineering ,Volume2013, Article ID 973903, 9 pages