Experimental Investigation On Charpy Impact Response Of Kenaf Bast Fibre Reinforced Metal Laminate System

Natural fibre triggers the researcher's interest due to its advantage over synthetic fibres as it is inexpensive and eco-friendly. The objectives of this study is to investigate the effect of fibre length, loading and chemical treatment of kenaf bast fibre reinforced polypropylene metal laminate under Charpy impact loading. The kenaf bast fibre loading of 50wt%, 60wt% and 70wt%, fibre length of 3 cm, 6 cm and 9 cm and chemical treatment of 0% and 5% NaOH are considered. Aluminium, 5052-O is employed as the skin for the composites in this research. The composite and FML were fabricated using hot compression moulding method. Specimens were extracted from the prepared FML panels using water jet cutter and tested in accordance to ASTM E-23 using INSTRON CEAST 9050 pendulum impact tester. The results show that the alkaline treated kenaf fibre with fibre loading 70wt% and length 9 cm absorbed the highest impact energy at 157.04 kJ/m2 compared to other fibre metal laminate compositions

Reduction of a Vehicle Multibody Dynamic Model Using Homotopy Optimization

The original publication is available at: Hall, A., Uchida, T., Loh, F., Schmitke, C., & Mcphee, J. (2013). Reduction of a Vehicle Multibody Dynamic Model Using Homotopy Optimization. Archive of Mechanical Engineering, LX(1). https://doi.org/10.2478/meceng-2013-0002Despite the ever-increasing computational power of modern processors, the reduction of complex multibody dynamic models remains an important topic of investigation, particularly for design optimization, sensitivity analysis, parameter identification, and controller tuning tasks, which can require hundreds or thousands of simulations. In this work, we first develop a high-fidelity model of a production sports utility vehicle in Adams/Car. Single-link equivalent kinematic quarter-car (SLEKQ, pronounced “sleek”) models for the front and rear suspensions are then developed in MapleSim. To avoid the computational complexity associated with introducing bushings or kinematic loops, all suspension linkages are lumped into a single unsprung mass at each corner of the vehicle. The SLEKQ models are designed to replicate the kinematic behaviour of a full suspension model using lookup tables or polynomial functions, which are obtained from the high-fidelity Adams model in this work. The predictive capability of each SLEKQ model relies on the use of appropriate parameters for the nonlinear spring and damper, which include the stiffness and damping contributions of the bushings, and the unsprung mass. Homotopy optimization is used to identify the parameters that minimize the difference between the responses of the Adams and MapleSim models. Finally, the SLEKQ models are assembled to construct a reduced 10-degree-of-freedom model of the full vehicle, the dynamic performance of which is validated against that of the high-fidelity Adams model using four-post heave and pitch tests.The authors gratefully acknowledge the financial support provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the NSERC/Toyota/Maplesoft Industrial Research Chair program

Compliant Multi-Link Vehicle Suspensions

One of the goals of automotive lightweight engineering is to achieve reduction in mass, cost, and complexity of vehicle components, subsystems and systems without sacrificing functionality and expected performance. This thesis addresses functionally integrated suspension systems that could lead to reduction in part count and mass and save packaging space. It deals with the analysis of multi-link suspensions that combine the function of energy storage and the mechanism of wheel location and guidance within individual compliant links and members. To explore possibilities, a generic kinematic model of an independent five-link suspension was built in the MSC.ADAMS multi-body dynamics simulation environment. Models of the compliant energy storage and kinematic guidance members were created using a finite element analysis package and interfaced with the MSC.ADAMS environment. Then, the main spring, and individual and multiple rigid links of the reference suspension were replaced with compliant members, and subsequently, the resulting kinematic characteristics of the compliant multi-link suspension were compared against those of the reference rigid multi-link suspension. Under certain achievable assumptions and a suitable choice of the dimensions of the compliant links, it was found that similar kinematic characteristics as the reference suspension could be achieved by variants of the compliant multi-link suspension consisting of compliant links. The analysis was also applied to the development of a compliant suspension concept for an existing high performance vehicle. Model validation data were obtained from actual tests conducted on a kinematic and compliance test rig. Evaluation of possible compliant variants of the rear suspension for this vehicle led to the replacement of the upper control arm of the original suspension with a ternary-link compliant member. The kinematic and compliance characteristics of this modified suspension were thoroughly analyzed through simulations and some of the characteristics were validated with tests conducted using a test-fixture employing many parts of the actual suspension and an aftermarket composite member for the compliant ternary-link. The compliant suspension concepts evaluated in both phases use fewer parts, and therefore exhibit reduced mass and complexity. Further research and development is required to comprehensively optimize the design of the compliant links for certain desired response attributes, such as better toe control

Formulation of a Path-Following Joint for Multibody System Dynamics

The development and validation of a new multibody joint that constrains a body to follow a spatial path and an orientation defined by a user is presented. The resulting joint has a single degree of freedom (DOF), and maintains equivalent kinematic behaviour when compared to higher-fidelity models. As such, it is referred to as a single-DOF equivalent kinematic (SEK) joint. The primary application of this joint is in the reduction of complex multibody systems, specifically vehicle suspensions. The first formulation of the joint is developed using the user interface of MapleSim. Starting with a planar particle joint, the theory is extended to a full 3D rigid body constraint. At each development stage, the joint is successfully validated against conventional models in both Adams and MapleSim. This formulation of the joint results in the kinematic pair being represented by a system of differential algebraic equations (DAEs) which is not the desired functionality, and so a second formulation is developed. By removing the constraint of using the MapleSim user interface, the formulation can be developed from first principles. Using the path-length as the coordinate for the joint, and the Frenet-Serret equations to compute the motion and reaction spaces, the kinematic pair can be represented by a single ordinary differential equation (ODE). The theory is implemented in the MapleSim source code using the symbolic computing language Maple. The theory of the SEK joint can be extended to create different joints. The first is the compliant SEK joint. In this version of the joint, the body is constrained to move along a spatial path using a simple linear bushing model. The compliant SEK joint is useful for modeling the suspension systems of passenger cars as bushings are used extensively in these systems to increase passenger comfort. The second extension is to add an additional DOF to the SEK joint to created the double-DOF equivalent kinematic (DEK) joint. The DEK joint is useful for modelling steered suspension systems as the steering introduces an additional DOF to the suspension. The envelope of motion for the steered wheel is a surface rather than a spatial line. Once the joints are successfully validated, three example applications of the joint are shown. In the first, rigid, compliant and steered suspension models are developed and compared against high-fidelity models in Adams/Car and MapleSim. Next, a full vehicle model is assembled using the suspension models and compared against an equivalent high-fidelity full vehicle model built in MapleSim. The comparisons show the accuracy of the SEK joint as well as the simulation speed improvements it can offer compared with conventional modelling techniques. The second example, from the domain of biomechanics, shows a knee model created using the SEK joint. Finally, a roller coaster model is created to demonstrate the flexibility of the path generation algorithm to create splines that represent complex paths

Geometry optimization of double wishbone suspension system via genetic algorithm for handling improvement

Motion control, stability maintenance and ride comfort improvement are fundamental issues in design of suspension systems in off-road vehicles. In this paper, a double wishbone (DW) suspension system, mostly used in off-road vehicles, is modeled using ADAMS software. Geometric parameters of suspension system are optimized using genetic algorithm (GA) in a way that ride comfort, handling and stability of vehicle are improved. Simulation results of suspension system and variations of geometric parameters due to road roughness and different steering angles are presented in ADAMS and effects of optimization of suspension system during various driving maneuvers in both optimized and non-optimized conditions are compared. Simulation results indicate that the type of suspension system and geometric parameters have significant effect on vehicle performance

A Methodology for Parameter Estimation of Nonlinear Single Track Models from Multibody Full Vehicle Simulation

In vehicle dynamics, simple and fast vehicle models are required, especially in the framework of real-time simulations and autonomous driving software. Therefore, a trade-off between accuracy and simulation speed must be pursued by selecting the appropriate level of detail and the corresponding simplifying assumptions based on the specific purpose of the simulation. The aim of this study is to develop a methodology for map and parameter estimation from multibody simulation results, to be used for simplified vehicle modelling focused on handling performance. In this paper, maneuvers, algorithms and results of the parameter estimation are reported, together with their integration in single track models with increasing complexity and fidelity. The agreement between the multibody model, used as reference, and four single track models is analyzed and discussed through the evaluation of the correlation index. The good match between the models validates the adopted simulation methodology both during steady-state and during transient maneuvers. In a similar way, this method could be applied to experimental data gathered from a real instrumented car rather than from a multibody model

Multi-Body Vehicle Dynamics Modeling for Drift Analysis

One area of vehicle handling performance that has been the focus of an OEM{'}s (Original Equipment Manufacturer) engineering effort is within the realm of vehicle straight-line performance. As the name implies, straight-line performance is determinant on the vehicle{'}s tendency to resist vehicle lateral drift when being driven straight. Vehicle lateral drift is a condition where the driver must apply a constant correctional torque to the steering wheel in order to maintain a straight line course. A full vehicle model was developed to simulate the influences of suspension parameters on vehicle drift. Adams 2010 was chosen as the multi-body dynamics (MBD) software for this research for its ability to develop a full vehicle high fidelity model without the need for physical test data. The model was created from standard Adams/Car suspension templates modified to accommodate the subject vehicle. The front suspension sub-assembly model was built upon the front MacPherson strut suspension template. Likewise, the rear suspension sub-assembly model was created from the rear multi-link suspension template. The tire model used in the full vehicle model was based on the Pacejka 2002 formulation. A model of a similar tire was generated using a custom spreadsheet based on the PAC2002, a slightly modified version of the Pacejka 2002 formulation found within Adams/Car. A virtual tire test rig and a 6/7-DoF model were created to understand and verify the behaviour of the generated tire models. The virtual tire test rig was used to compare the outputs of the PAC2002 tire model to the calculated values from a custom tire property spreadsheet. The 6/7-DoF model was used to test and verify the effect of the tire{’}s residual lateral forces. The full-vehicle model was verified using the parallel wheel travel and opposite wheel travel suspension analyses. The parallel wheel travel analysis was used to tease out binding issues within the designed travel of the suspension. The opposite wheel travel analysis was used similarly for anti-roll bar systems. Simulations based on the industry standard vehicle drift tests were run to understand the effect of certain vehicle suspension geometry on vehicle drift, namely the vehicle{’}s front and rear camber and toe angles. The full-vehicle model was also subjected to straight-line performance simulations with various road bank or crown angles. The results were compared with industry-standard vehicle drift test data gathered by the OEM on their own test track. The results indicate that the direction of vehicle pull matches with the OEM test data, but the magnitudes differ in both the positively and negatively banked road simulation results. It is likely that the difference in vehicle drift is due to the lack of steering data obtained for the full-vehicle model

Design and Analysis of Suspension System for a Formula SAE Race Car

The objective of this project is to further optimize the suspension system of a Formula SAE race car with steering system included. The suspension system is designed based on unequal length double wishbone suspension system. Several changes had beenmade for the new car with the usage of hybrid composite-spaced frame chassis and single cylinder engine. Thus, new design concepts has been introduced to suit the changes made for the vehicle which include the changes in mounting points, weight distribution, suspension kinematics plane,and steering geometry. The scope of study consists of modeling the suspension and steering components by using computeraided softwaresuch as CATIA. In addition, the Finite ElementAnalysis (FEA) is performed by using CATIA which could give instantaneous yet accurate results. Dynamics analysis will compromise the usage ofADAMSCAR software which can simulate the whole suspension and steering system behavior according to the track layout which will make better understanding regarding the study. Although the fabrications of the actual product will not being carried out, the fabrication method will be inserted together in this study as reference for future planning. Based on the designing and analysis performed, the calculated roll center height and static camber angle ofthe vehicle at the static position is -68mm from the ground and - 0.5 degree respectively. In addition, the maximum lateral load transfer being transferred during cornering with radius of7.5 meters is 91.82 N. The dynamics analysis performed in ADAMSCARS shows remarkable results in open loop step steer simulation. These results provide better understanding of the vehicle performance during the autocross events

New dynamic modeling and pratical control design for MacPherson suspension system

The ride quality, handling, and stability are three main issues in vehicle suspension design. Different suspension systems have been designed in the past to fulfil these conflicting requirements. One of the popular suspension systems integrated in small and midsize passenger cars is MacPherson suspension system. A suspension system is either passive if a conventional damper is incorporated or is semi-active with a variable damper. A new control oriented dynamic model of the MacPherson suspension system is developed in this thesis to consider the effects of the suspension structure on the dynamic response and a new kinematic model is proposed to investigate those suspension kinematic parameters affecting both handling performance and stability of the vehicle. The performance of MacPherson suspension system under alternative hybrid semi-active controls is evaluated. It is shown that the contribution of different control strategies on the ride quality enhancement of the vehicle could be similar whereas their effectiveness on the performance of suspension kinematc parameters is completely different. Using the H {592} robust control theory, a full state feedback controller is designed to improve MacPherson suspension specifications. The gain of the controller is optimized so that the trade-off between the requirements is achieved. To be more practical and to reduce the design cost, H, output feedback control theory is employed to design a controller with the minimal cost design. To optimize the controller gain, the LMI and Genetic Algorithm optimization tools are used. It is shown that the output controller can improve the suspension performance close to that of a full state feedback controller. A magnetorheological damper with continuously variable damping is considered as the actuator to the system. In order to tune the current signal of the damper so as to track the desired force calculated from the controller unit, a mathematical dynamic model of the damper is required. For modelling the damper, the MR damper is characterized by a piece-wise polynomial model which is identified by using the data acquired from various tests in the laboratory. The dynamic behaviour of the MR damper on control performance is investigated. The Hardware-in-the-Loop Simulation is made and the effectiveness of the controllers is evaluated through experiments