Dört tekerlekten çekişli askeri araçların kurtarma mapası ve vinç kulesi yapısal tasarımı, analizi ve optimizasyonu
Eyebolt and crane tower structural design, analysis and optimization of four wheel drive in military vehicles
Yazar: EMRE DELİBAŞ
Danışman: PROF. DR. CEVAT ERDEM İMRAK
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Makine Mühendisliği Ana Bilim Dalı / Konstrüksiyon Bilim Dalı
Derece: Yüksek Lisans, 2021
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
Günümüzde çeşitli askeri araçlar mevcuttur. Her askeri araç kendi aralarında görev kabiliyetleri bakımından sınıflandırılır. Gerek terör saldırıları gerek sınır ötesi harekatlar gerekse meskun mahal için kullanılan kara araçlarında farklı özelikler istenir. Bu araçların ortak özellikleri içerisinde bulunan personelleri belirli koruma seviyelerine kadar dış tehditlerden korumaktır.
Askeri araçalarda olabildiğince az komponent olması arızalanmalara ve görev sırasında bozulup aracın görevini olumsuz etkileme risklerine karşı önemlidir. Bazı parçalar zorunluluktan dolayı olmazsa olmaz, bazıları ise zor ve ekstrem şartlar için görev türüne göre anlık olarak araca montaj ve demontaj yapılabilmektedir.
Bu çalışmada dolu yükü 6400 kg olan 4 x 4 ve paletli askeri araçların ekstrem durumlarda kullanılması ve bu durumlardan dolayı arızalanması, yolda kalması senaryosu işlenerek aracı kurtarma ve çekme için vinç tasarımı ile mapaların tasarımı analizi ve optimizasyonu ele alınacaktır.
Tasarlanan mapalar ve vinç taşıyıcı askeri araçta kullanılacak olup analiz ve testleri başarı ile gerçekleştirmesi durumunda kullanılacak olup zorlu şartlarda aracı yolda veya bataklıktan kurtarma görevini üstlenecektir. Bu çalışma kapsamında mapa ve vinç tasarımı yapılacaktır. Yapılan tasarımlar sonlu elemanlar yöntemi ile analiz edilecek, analiz sonuçlarına göre geliştirme ve düzenlemeler yapılacaktır. Bu tez beş kısımdan oluşmaktadır.
Birinci kısımda, tezin amacı ifade edilmiştir. Askeri 4 x 4 araçlar ve paletli araçlar ile ilgili genel bilgiler bulunmaktadır. Burada araçların görevlerine göre özelliklerinden bahsedilmişitr.
İkinci kısımda çeşitli askeri araçlarda kullanılan mapalar ve vinç kulesi tasarımları incelenecektir. STANAG (Standartization Agreement), NATO paktına üye ülkelerin askeri alanda uyması gereken standartları belirleyen birimdir. NATO'ya üye ülkeler bu standartlara uymak zorundadır. Bu kısımda STANAG kurtarma senaryolarında ilgili yerleşke ve standartları belirtilecektir. Geçmişte yapılan deneyler ve analizler ile ilgili çalışmalar verilecektir.
Üçüncü kısımda askeri standartlara göre kurtarma prensipleri ile ilgiler bilgiler verilecektir.
Dördüncü kısımda mapa tasarımı analitik hesaplamaları ve hesaplama standartları verilmiştir. Burada araca uygun olacak şekilde mapa hesapları boyutlandırılmaları yapılmış ve araca teorik olarak uygun mapa ölçülendirilmesi yapılmıştır.
Beşinci kısımda ise tasarımı yapılan parçaların statik analizi için simülasyonları yer almaktadır. Simülasyonlar Ansys Workbench programında gerçekleştirilmiştir. Yapılan simülasyonda standartlar ve test koşulları simüle edilmeye çalışılıp kritik bölgeler ve dayanımı, uygunluğu incelenecektir. Burada bulunan hesaplanan sonuçlar tartışılacak olup varsa gerekli iyileştirmeler, sonuçlar ve uygunluğu tartışılacaktır.

Abstract:
Various military vehicles are available today. Each military vehicle is classified among themselves in terms of their mission capabilities. Different characteristics are required for land vehicles used for terrorist attacks, cross-border operations and residential areas. The common feature of these tools are to protect personnel from external threats up to certain levels of protection. Also, every country needs different requirements for military vehicle. Some countires prefer to powerful engines and high protection level vehicle such as Turkey, UAE, Koweit, some countries prefer to low protection level vehicle or unarmoured vehicle. Geographical location, aim of vehicle, terror attacks, social revolts, state of emergency and type of missions determine type of vehicle. 
Having as few components as possible in military vehicles is important factor that decreases risk of breaking down during the mission. Some parts are indispensable due to necessity and some parts can be assembled and disassembled according to the type of duty for difficult and extreme conditions. 
Using military vehicles' in extreme situations and their failure due to these situations and stranded scenario will be discussed and anlyze of crane and eyebolts designs to rescue towing operations for fully loaded armoured four wheel drive  military vehicle's in extreme military situations will study in this thesis. Armoured vehicle has 180 hp , 600 Nm torque. Vehicle unladen weight is 5600 kg and fully loaded weight is 6400 kg. Axle load capacities are 2900 kg for front axle and 3500 kg for rear axle. Tire size is 37 x 12.5 R16. Also, vehicle has run flat for protection of vehicle movement sustainablity. Investigated vehicle's slope climbing capability is %60 and side slope capability is %30. Slope values are important because of roll possibility during rescue operation. Vehicle spring mass is 5900 kg and unsprung mass is 500 kg.
The designed eyebolts and crane carrier will be used in the military vehicle. Eyebolts and crane carrier will be used the tasks of rescuing the vehicle on extreme conditions in case of successful anlaysis and tests. The design will be analyzed with finite elements method and if some improvements are neccesery, improvements will made according to analysis results. Analysis was conducted with ANSYS Workbench 16.2 programme. Various meshs are used and some contact types were used. 
Totally 632000 elements were used in this investigated. While first order shell elements were used some areas, second order shell elements were used necessery locations. First order triangle elements, second order triangle elements, first order quadrilateral meshes and second order quadrilateral meshes were used. Node to node connection method were used in effective area. On the other hand welding connection method were used in uneffective area. The results were conducted with STANAG rescue operations linear pulling, 22.5 degree horizontal pulling and 40 degree vertical pulling test scenario. There are some test scenarios according to STANAG such as mire resistance and water resistance. Wheel depth mire, fender depth mire and turret or cab depth mire. Theese are called mire resistance. Wheel depth mires occur when wheeled vehicles are mired up to the hub but not over the center. Tracked vehicles are mired up to the road wheels but not over the top. Estimate wheel-depth resistance as  equal to the weight of the vehicle plus cargo. Fender depth mires occur when wheeled vehicles are mired over the top of the hub but not over the fender. Tracked vehicles are mired over the top of the road wheels but not over the fender. Estimate fender depth mire resistance as twice the total weight of the vehicle plus cargo. Turret or cab depth mires occur when vehicles are mired over the top of the fender. Estimate turret/cab depth mire resistance as three times the total vehicle weight plus cargo. Water resistance occurs when submerged vehicles are pulled from water to land. Estimate the amount of resistance met in the same way as for land recovery. In some instances, the resistance to overcome is less than the rolling resistance of the same vehicle on land. There are some correction factor for mire and water resistance. If the vehicle in wheel depth, mire correction factor is chosen one and it means total load is same with vehicle weight. If the vehicle in fender depth mire and turret or cab depth mire, correction factor chosen two and it means total load is equal to twice the vehicle weight. If the tracked vehicle in mired over the top of the road wheels but not over the fender, correction factor is chosen three and it means total load is equal to three times the vehicle weight. Analyzes were conducted with theese mire scenarios. This thesis consists of five parts.
In the first part, the aim of the thesis is indicated. There are some informations of various military 4 x 4 vehicles and tracked vehicles such as special operation vehicles, armoured vehicles, commender vehicles. All of vehicle types are classifcated with operation type. Most of vehicle that given information type are 4x4 wheeled vehicles. In addition, the features of vehicles will be mentioned according to operation missions. All vehicle photographs are indicated in first section and type of vehicle will come out. 
In the second part, eyebolts and crane tower designs in various military vehicles will be investigated. Military standards will be given according to military standards that STANAG (Standardization Agreement) rescue scenarios. Types of rescue, eyebolt angles, rope angles, vertical and horizantal rescue scenarios, maximum and minumum standard angles will given. Rescue elements such as ropes and maintanance will explained. Also, previous studies of eyebolts experimentes and analyzes will investigate. Eyebolt calculation methodology and design is investigated in this section and results will explained according to standards.  
In the third part, some informations of rescue principles according to millitary standards, will be given. There are some standards for rescue kits. Force source, strength, sloshing, roll scenario is explained according to military standards. NATO countries have to use that standards for their vehicles. This standards will be explained in third section. Grade resistance, overturning resistance, mire resistance, water resistance, tackle resistance will explained and calculated. Rollover is observed frequently in extreme condition such as bog. Vehicle performance is affected by mud resistance. In this section all  scenarios and all rescue type with eyebolt  will explained according to military standards.
In the fourth part, eyebolt anlytical calculations and standards of calculation will be given. In all scenarios, calculations, anlysis and tests are conducted with the worst situation for military vehicle because of risk enemy attack. So, military vehicles have to provide safe itself rapidly and should move away safely. There are some standards for rescue operation calculation. Analytical calculations of eyebolts are made according to Norsok Standards in this investigated. In this part, we will discuss calculation standards, methods and formulas. Importance of safety factor and how it 
effects to results will explained. Eyebolt design and dimensions are given in this section according to military standardization standards. Thickness, hole diameter, eyebolt radius are indicated according to standards and calculations. Also, suitability of eyebolt dimensions and calculations were made according to vehicle loads and STANAG (Millitary standards). Eyebolt safety coefficient is between 0 and 6. Safety coefficient is selected 5 for this investigated. Safety factor is importent thing for the strength results and it effects to all theoric calculations. Also eyebolt welding strength was calculated. Welding quality is important for stregth such as first quality welding , second quality welding and third quality welding. Welding quality effects to material strength. Third quality welding causes low welding safety stress and it effects to low tensile strength especially in dynamic loads for welding areas. First quality welding causes low welding safety stress and it effects to high tensile strength especially in dynamic loads for welding areas. Also, welding groove is very important for high quality welding process. It effects to strength especially dynamic load conditions and calculation results. Dynamic loads were effected to eyebolts for eyebolt strength. 
The aim here is to investigate the case of breaking the connection surface of the eyebolt and the entire load acting on a single eyebolt. In dynamic condition, dynamic load is equal to twice of total load. Dynamic loads are the highest loads and high risk for components  according to STANAG rescue scenarios. 
In the fifth part, there are some simulations for the static anlysis of designed parts. Anlyzes were conducted with Ansys Workbench program. Standards and test conditions will simulated. Also critical areas and design suitability is investigated. Analyse results will discussed. Theorical calculation and analytic calculation results were found smilar, it was effected the results and safety factor importance is indicated. All analyzes results were indicated in the pictures, detailed and explained. Maximum stress, maximum deformations are calculated for all military rescue operation conditions. If analysis results are not enough for material strength of S700 structural steel, some optimizations and design changings must be done such as material thickness, material bending radius, welding quality and bending radius improvements are discussed. Material thickness improves to moment of strength and it provides to  decrease to maximum strength. Material bending radius effects to maximum stress on bending area. If  bending area is high as much as, stress distrubiton is located wide area and unit area stress will decrease. 
Furthermore, the results have to validate according to STANAG test scenarios. Dynamic loads and variable forces effects to endurance of eyebolt and crane tower, so dynamic loads will make an impact in tests. According to test results crane tower and 
eyebolt will homologate and if test results are prospering, the crane tower and eyebolt design will used on four wheel tracked military vehicle.