Bell Crank Research Articles

Failure analysis of non-rotating control rod of a helicopter

The paper presents findings of the failure analysis of a control rod that resulted in accident to a helicopter during a routine flight. The helicopter crashed due to several events that led to loss of control. Post-accident wreckage examination showed that failure in the non-rotating control rod connecting the swash plate and bell crank was the primary component that led to the accident. The control rod was manufactured from Ti-6Al-4V alloy. Fractography studies revealed that the control rod failed by fatigue mechanism. The fatigue crack initiated at the rod-to-eye-end transition fillet. Fatigue crack initiation was associated with presence of deep machining marks on the fillet surface. After initiation at the machining marks, the crack propagated through the thickness as well as along the machining mark over a length on either side of the crack origin. Study revealed presence of multiple fatigue cracks on the machining marks on the fillet surface. Analysis showed that the primary cause of the fatigue failure of the non-rotating control rod was the stress concentration effect arising from the deep machining marks at vulnerable location, which is the rod–to–eye transition fillet surface. Issues related to the fitment of the bearing in the control rod led to fretting on the inner bearing surface, and this damage contributed to the initiation of the fatigue cracks.

Development of Load Reconstruction Technique and Application on Commercial Vehicle Suspension

<div>The ability to predict the durability of a structure depends on the knowledge of operating loads experienced by the structure. Typically, multi-body dynamics (MBD) models are used to cascade measured wheel loads to hard points. However, in this approach, there are many sources by which errors creep into cascaded forces. Any attempt to reduce sources of such errors is time consuming and costly. In typical program development timelines, it is very difficult to accommodate such model calibration efforts. Commercial load cells exist in the industry to give engineers insight into understanding the complex real-world loading of their structures. A significant limitation to the use of load cells is that the structure needs to be modified to accept the load cell, and not all desired loading degrees of freedom (DOFs) can be measured. One of the innovative solutions to calculate operating loads is to convert the structure itself into its own load transducer. The D-optimal algorithm along with the pseudo-inverse technique provides a theoretically sound and versatile method to identify optimum positions and locations to place the sensors (i.e., strain gauges) on the structure where its response is to be measured. A pre-calculated calibration matrix through pseudo-inverse is then used along with measured responses to reverse calculate loads acting on the structure. The accuracy of calculated loads with this approach is typically high compared with conventional load cascading methods as sources of errors are less in this method.</div> <div>This work is focused on load reconstruction, FE analysis, and lightweighting of the bell crank lever of a commercial vehicle. Practical difficulties associated with the load reconstruction method and solutions are also discussed in this research paper.</div>

Topology Optimization of a Bell Crank Lever Based on Stiffness and Mass using Finite Element Analysis

The following paper represents the topology optimization of a bell crank lever used in trucks. Current trends indicate a steep rise in the use of topology optimization in all fields. There arises a need for such optimized parts in the automotive industry to increase the overall efficiency of any vehicle. The aim of the present research is to optimization of a bell crank lever arm made of AISI A514 Steel used in trucks and maximizes its performance based on criteria of stiffness and mass. Initially, the model is subjected to loading conditions in accordance with a worst-case scenario and optimized accordingly. The optimized and existing bell crank lever is subjected to static analysis using FEA. Results show a 22 % mass reduction of the crank (3395.71 grams to 2641.02 grams) and a 40% stiffness increase (389.32N/mm to 644.988N/mm) which suits the purpose of the study.

Fractal Analysis for Fatigue Crack Growth Rate Response of Engineering Structures with Complex Geometry

A growing fatigue crack in metallic materials and structures exhibits multifractal features that inherit signatures of the crack growth rate behavior of the material. This study exploits the recently established multifractal fatigue crack growth model to quantify the characteristic fatigue crack growth rate response of the AISI 410 martensitic stainless steel using an L-shaped bell crank structure. The objective is to demonstrate that the fatigue crack growth rate response of the material could be established by quantifying the fractality of the growing crack. The fractal approach avoids the need of the crack geometry factor when calculating the crack tip driving force. The fractal analysis of the crack image employs the box-counting algorithm to determine the fractal dimension along the edge of the crack length. The analysis is confined to the power law crack growth rate stage (Paris crack growth regime). Results show that the fatigue crack growth path in the bell crank structure is dictated by the Mode I (opening) component of the crack loading. The distribution of fractal-based fatigue crack growth rate data is within the 99% confidence limit of the median crack growth response by the Paris equation. Thus, the model could be employed for prediction of the fatigue crack growth response of engineering structures where the crack geometry factor is not readily available.

A Comparative Study of the Application of Different Commercial Software for Topology Optimization

Topology optimization (TO) has been a popular design method among CAD designers in the last decades. This method optimizes the given design domain by minimizing/maximizing one or more objective functions, such as the structure’s stiffness, and at the same time, respecting the given constraints like the volume or the weight reduction. For this reason, the companies providing the commercial CAD/FEM platforms have taken this design trend into account and, thus, have included TO in their products over the last years. However, it is not clear which features, algorithms, or, in other words, possibilities the CAD designers do have using these software platforms. A comparative study among the most applied topology optimization software was conducted for this research paper. First, the authors developed an online database of the identified TO software in the form of a table. Interested CAD designers can access and edit its content, contributing in this way to the creation of an updated library of the available TO software. In addition, a deeper comparison among three commercial software platforms—SolidWorks, ANSYS Mechanical, and ABAQUS—was implemented using three common case studies—(1) a bell crank lever, (2) a pillow bracket, and (3) a small bridge. These models were designed, optimized, and validated numerically, as well as compared for their strength. Finally, the above software was evaluated with respect to optimization time, optimized designs, and TO possibilities and features.

Structural analysis of bellcrank in a pullrod suspension system in an FSAE prototype

The cause of accidents due to suspension failure is fatigue. The goal of this project was to design a bell crank for an FSAE prototype to withstand fatigue loads and reduce the chances of failure during its use. After finding the bellcrank forces, the dimensions of the bellcrank and the associated OEMs (bearings) are calculated and found. This was followed by CAD modelling and structural optimization using Autodesk Fusion 360 software. Finally, finite element analysis was performed and a comparative study was done between the new and old model of bellcrank assembly based on mass, fatigue life and factor of safety and the results were acknowledged.

TOPOLOGY OPTIMIZATION OF THE BELL CRANK & BRAKE PEDAL

Topology Optimization has been an effective tool for weight reduction and performance design and has essential applications in automobile industry. The main objective of this paper is to design a lighter weight bell crank and brake pedal than the existing design which is generally used in the automobile parts. The newly optimized design of bell crank and brake pedal is compared with the existing design. The CAD model of the bell crank and brake pedal is modeled using SOLIDWORKS software and the analysis of the newly optimized model is carried out using the Altair INSPIRE 9.5 . Using the above methodology, a light weight bell crank and brake pedal model is designed and the FEA analysis is used for obtaining the maximum and minimum value of displacement, % of yield, tension/compression, shear stress and von mises stress on the optimized design. The results of the design reflect that the weight of the bell crank has been reduced to 140 grams which is about 24% less weight then the existing design and the optimized weight of the brake pedal is reduced from 363g to 211g.

Reverse Engineering and Topology Optimization for Weight-Reduction of a Bell-Crank

This paper describes a new design method that was developed to achieve an optimal design method for weight reduction of a bell crank, sourced from a Louis Christen Road Racing F1 Sidecar. The method involved reverse engineering to produce a 3D model of the mechanical part. The 3D bell crank model was converted to a finite element (FE) model to characterize the eigenvalues of vibration and responses to excitation using the Lanczos iteration method in Abaqus software. The bell crank part was also tested using a laser vibrometer to capture its natural frequencies and corresponding vibration mode shapes. The test results were used to validate the FE model, which was then analysed through a topology optimization process. The objective function was the weight and the optimization constraints were the stiffness and the strain energy of the structure. The optimized design was converted back to a 3D model and then fabricated to produce a physical prototype for design verification and validation by means of FE analysis and laboratory experiments and then compared with the original part. Results indicated that weight reduction was achieved while also increasing the natural frequency by 2%, reducing the maximum principal strain and maximum von Mises stress by 4% and 16.5%, respectively, for the optimized design when compared with the original design. The results showed that the proposed method is applicable and effective in topology optimization to obtain a lightweight (~3% weight saving) and structurally strong design.

3D Modelling and Analysis of Bell Crank Mechanism

3D Modelling and Analysis of Bell Crank Mechanism

Design and Optimization of Suspension and Steering System of Efficycle – Human Powered Hybrid Tricycle

Suspension is a system of tires, springs, shock absorbers, and linkages that connects a vehicle’s chassis to its wheels and allows relative motion between the two. Steering is a mechanism that provides a direction to the vehicle, it basically consists of gears, shaft, joints, steering column, steering wheel, and furthermore. The main objective of this paper is to design a system of suspension and steering for a three-wheeled human-electric hybrid trike. A system of directly actuated double wishbone suspension system is chosen for the front and a pushrod actuated 2-link trailing arm suspension system for the rear. The steering system used is a type of Single tie rod and drag link system. A knuckle-to-knuckle drag link provides continuity to the wheels and a tie rod to the bell crank provides steering rotation. This paper also talks about the single nut hub-shaft system which is being used in the front suspension system. Based on the research using various input parameters, the inboard and outboard suspension hardpoints are decided to maximize the tire contact patch at every vehicular motion (mainly during body roll). Forces and stresses are calculated with the help of Free Body Diagrams (FBD) and Multi-Body Dynamics (MBD) software LOTUS Shark. The paper discusses the calculations regarding the roll and ride rates and for the custom springs of specific stiffness used in front and rear shock absorbers and the variation of roll steer and bump steer on changing various parameters of the steering system. Key points also include the procedure of selections of various types of bearings, rod ends, and bolts. This paper also talks about laser-cut jigsaw uprights that are used in the front wheel assembly. The finite element method was used to analyze the designs using DS Solidworks and Ansys Workbench. Static structural and explicit dynamics analysis was performed on the wheel assembly components both individually and assembled

Analysis of Watt’s linkage under dynamic loading

From past few years, there has been a rising trend of using composite materials for suspension system of vehicles as it reduces overall weight to a great extent. Also, they are unaffected by chemicals and corrosion. Watt’s linkage is an assembly of a bell crank and two horizontal rods of equal length. It is a mechanical linkage in which the bell crank is pivoted to axle at its centre traces vertical line, allowing axle to move vertically. The assembly is connected to the chassis of the vehicle with help of the horizontal rods, which constraints the lateral movement of body of vehicle and locates the axle under the vehicle. Low alloy steels are commonly used material for manufacturing the linkages in suspension system. In this paper, the Watt’s linkage components are designed and assembled in PTC Creo 3.0 and the finite element analysis of Watt’s linkage for two materials, namely, AISI 4142 steel and Carbon Fibre Reinforced Polymer (CFRP) is carried out. The results for total deformation and equivalent stress are produced using ANSYS Workbench 2019 R2 for dynamic loading. The maximum total deformation for 4142 steel is 0.31891 mm and for CFRP is 2.6298 mm.

TOPOLOGICAL OPTIMIZATION OF THE FORMULA STUDENT BELL CRANK

TOPOLOGICAL OPTIMIZATION OF THE FORMULA STUDENT BELL CRANK

Comparative study on the performance of different drive mechanisms used in a beta type Stirling engine through thermodynamic analysis

In this study, thermodynamic and kinematic analyses of bell crank, slider crank, rhombic and scotch yoke drive mechanisms were performed for a beta type Stirling engine with a swept volume of 365 cm3. The kinematic analyses of Stirling engines with these different drive mechanisms were investigated by using the MSC Adams program, and the pressure-volume variations depending on the crankshaft angle were determined by using the isothermal analysis method. It was determined that compression and expansion volume values of rhombic drive mechanism were close to each other, while compression volume value was extremely higher than expansion volume value in other drive mechanisms. For this reason, in this research conducted with working fluid of equal amount (m=0.000716 kg), for all of drive mechanisms, it was determined that engine with rhombic drive mechanism generates 19.2% net work more than the other drive mechanism. The masses of working fluid used in 1 bar charge pressure from engines with bell crank, slider crank, rhombic and scotch yoke drive mechanism were 0.000716 kg, 0.000737 kg, 0.000536 kg and 0.000724 kg, respectively. The net work amounts obtained as a result of the thermodynamic analyses made for the 1 bar charge pressure value in bell crank, slider crank, rhombic and scotch yoke drive mechanisms are 12.85 J, 12.44 J, 11.61 J and 13.05 J, respectively. In this research conducted with working fluid in the same charge pressure, it was determined that 10.8% less net work was obtained from engine with rhombic drive mechanism. Since all the changes of the volume in the bell crank, slider crank and scotch yoke drive mechanisms are very close to each other, the net work performance values obtained with the equal amount of working fluid and the same charge pressure values are also very close to each other.

Study on Stress Analysis of Araldite HY-951 and CY-230 Bell Crank Lever using Photoelasticity and FEM

Bell Crank Lever is a bar capable of turning about a fixed point, used as a machine to lift the load by the application of small effort. Bell Crank Lever is used in railway signaling, governors of Hartnell type, the drive for the air pump of condensers, etc. The major stresses induced in the Bell Crank Lever at the fulcrum are bending stress and fulcrum pin is shear stress. The maximum stresses are developed at the fulcrum. The Bell crank is a type of crank that changes motion through an angle. The angle can be any angle from 0° to 360°, but 90° and 180° are most common. Hence, the work deals with the stress analysis of Bell Crank Lever within the angle ranges 90° to 180° by finite element method using ANSYS WORKBENCH 14.5 software and photoelasticity. Experimental and Analytical results are observed and compared, so that the obtained results are in close agreement with each other. For the photoelastic stress analysis which is the experimental method, the Bell Crank Lever models are prepared with photoelastic sheet of Araldite hardener HY-951 and curing agent CY-230 is used. Cite this Article Prasanth Kumar Mallipudi, M. Chandrasekhar, Kondapalli Siva Prasad. Study on Stress Analysis of Araldite HY-951 and CY-230 Bell Crank Lever using Photoelasticity and FEM. Journal of Automobile Engineering and Applications. 2017; 4(2): 10–21p.

LIFTING MECHANISM FOR ATTACHMENTS OF AGRICULTURAL EQUIPMENTS

In the field of agriculture numerous equipments are used for various purposes. These attachments like plough, harrow, chisel plough, cultipacker, etc are mounted on the operating machine through an attachment which is then lifted as per requirement with the help of a hydraulic mechanism. No matter how efficient a mechanism might be, cost has always been and will be an important factor to decide which lifting mechanism to opt for. Hydraulic mechanism being costly, this newly designed mechanism is one of the cheapest amongst all others in the market. The main objective of the design has been coping for the high cost and bulky nature of hydraulic mechanisms to meet the attachment lifting requirements of the hand operated light weight machinery. Relative sliding motion of wedges is used for lifting of load. The wedges are actuated by a power screw. Our mechanism is designed by keeping in mind the light weight attachments like plough, supreme, ultimus, etc of a power tiller. Though it can be used in agricultural machines involving lifting of various attachments with necessary changes in dimensions of our prescribed design. The same mechanism can be used for lifting action of other heavy weight attachments of heavy duty machines. One of the primary objective of the design has been to substantially reduce the cost and size of the existing mechanism. Box dimension of our design is comparatively much less than other designs available in the market. This reduction in cost makes the mechanism affordable for farmers of every class. For commercialization other electronic actuating mechanisms can be used with the basic design structure remaining the same. It was observed that of all components bell crank is the most critical component, which was successfully analyzed for the required load.

Навесное энергосберегающее захватное устройство для бесчокерной трелевки древесины при рубках ухода за лесом

Hydrokinetic diagram of the device for chokerless skidding is presented. Chokerless device for logging includes a frame, capture with two jaws and hydraulic cylinder of jaw gripping attached to the hinged system of tractor, linked via a double-hinged capture unit to one end of the bell crank, and between the second end of the bell crank and the frame there is pivotally mounted hydraulic cylinder for additional amortization of oscillations of grapple. The mathematical model of the process of logging trees is made. It includes a differential equation of whips pack and differential equation of motion of the accumulator piston.

Design and Autonomous Control of the Active Adaptive Suspension System of Rudra – Mars Rover

Semi or completely autonomous unmanned vehicles, remotely driven or controlled through artificial intelligence, are instrumental to foster space exploration. One of the most essential tasks of a rover is terrain traversing which requires the need of efficient suspension systems. This communication presents a suspension system giving degrees of freedom to every wheel with the help of linear actuators connected through bell crank levers. The actuation of linear actuators directly varies the height of every wheel from the chassis hence offering articulation to the rover. A control system is developed offering an algorithm for its autonomous actuation. This system proves instrumental for leveling of the chassis where any kind of slope, roll or pitch, may impute abstaining of payloads from efficient working. This was tried and tested successfully as a part of the rover developed by Team RUDRA from SRM University, INDIA (first Team from Asia and finishing at the fifth position) at University Rover Challenge 2013, held at UTAH, USA in May-June.

Kinematic Motion Analysis and Structural Analysis of Bellcrank Structures Using FEM

The results of kinematic motion analysis were used for the structural analysis based on data that the load applied to each part. The problem of the fatigue strength estimation of materials or components containing natural defects, inclusions or in homogeneities is of great importance for both a scientifically or industrial point of view. Fatigue behavior in components is often affected by the presence of residual stresses introduced by processes such as actuator system. Analysis can provide the estimation of the crack growth curves with sufficient accuracy, even in case of complicated bell crank structures which are crucial for preserving aileron integrity and which participate in transfer of load. Probability of crack detection or any other damage detection is a result of many factors. An endurance life prediction of bell crank is used finite element analyses. Endurance test data for slim test specimens were compared with the predicted fatigue life for verification.

Wind Tunnel Testing of a Helicopter Rotor Trailing Edge Flap Actuated via Pneumatic Artificial Muscles

An active trailing edge flap system, actuated utilizing Pneumatic Artificial Muscles (PAMs), is developed in this study. PAMs were chosen as the actuation method because of several attractive properties, including: high specific work and power output, an expendable operating fluid (air), and robustness. Because of their performance, PAM are a potential enabling technology for a variety of next-generation aerospace systems. The actuation system developed here is sized for a full-scale active rotor system for a Bell 407 scale helicopter. This system is designed to produce large Trailing Edge Flap (TEF) deflections (±20°) at the main rotor rotation frequency (1 rev−1) to create large amplitude thrust variations that enable primary control of the helicopter. Additionally, the TEF actuation system is designed to produce smaller magnitude deflections at higher frequencies, up to 5 rev−1 ( N + 1 rev−1), to provide vibration mitigation capabilities. The PAMs are mounted antagonistically in the root of each blade. A bell crank and linkage system transfers the force and motion of these actuators to a trailing edge flap on the outboard portion of the rotor. A reduced span wind tunnel test model of this system was fabricated and tested in the Glenn L. Martin Wind Tunnel at the University of Maryland at wind speeds of up to M = 0.3, which is the maximum test wind speed of the facility. The test article consisted of a 1.55 m long outboard section of a Bell 407 rotor blade cantilevered from the base of the tunnel with a 0.86 m, 15% chord plain flap that was driven by the PAM actuation system. Testing over a wide range of aerodynamic conditions and actuation parameters demonstrated the considerable control authority and bandwidth of the system at the aerodynamic load levels available in the tunnel. Comparison of quasi-static experimental results shows good agreement with analytical predictions made using a simple system model.

The Relation of the Geometric Parameters to the Maximal Principal Stress of Crankshaft

he transition fillet regions linking the bell crank and the crank-arm and linking the crankarm and the bearing journal are the regions where the strength is the weakest in crankshaft. Based on a crank-shaft model, the effect of the geometric parameters on maximal principal stress at the two transition fillet regions was analyzed using FEM and software ANSYS8.0. It was concluded that the maximal principal stress at the two transition fillet regions is related not only to the transition fillet radius but also to the bell crank length and the crank-arm width.