In the end, the chassis design is compared for weight, torsional stiffness and. Lelchuk, increasing the accuracy in calculating the loads in tractortrailer chassis and other structures on the basis of distribution curves of operational failures, collection. Everything ive seen and read about testing torsional rigidity uses this method, but some of the judges is design gave us a ton of flak for this. It can be seen that linear torsion stiffness is preferred in order to more accurately predict the chassis behavior. A comprehensive list of torsional rigidity the technical. The torsional stiffness is desired to be as high as possible since low torsional stiffness may cause resonance or vibration. The stiffness obtained from the developed stiffness model and finite element analysis fea is a close match, which proves the validity of the proposed model. It is generally thought that if torsional and vertical bending stiffness is satisfactory, then the chassis structure is expected to perform well. Jan 04, 2016 often the torsional stiffness or torsional rigidity of a car chassis is measured. Also the reasons for seeking a linear torsion stiffness value are presented. The torsional stiffness of the chassis with various combinations of added members in the front clip area, engine bay, roof area, front window and the area behind the roll cage was predicted using finite element analysis. Design methods to improve torsional rigidity fictiv. Design of a winston cup chassis for torsional stiffness. Design and analysis of space frame chasis for formula.
Pdf torsional stiffness improvement of truck chassis using. Torsional analysis of open section thinwalled beams the main purpose of this paper is to present one approach to the optimization of thinwalled i, z and channelsection beams subjected to constrained torsion. Lastly we predict those members that have a large effect on the overall stiffness of the chassis. Pdf chassis torsional rigidity analysis for a formula sae. The main differences are the specific material property to be used shear modulus of rigidity and the polar moment of inertia which is very similar to the area moment of inertia used in bending. Analysis of the cross member designs used for improving. A study on torsional stiffness of the competition gokart frame. Torsional rigidity has not yet been tested due to insufficient time to manufacture the rigging to do so. Appendices that provide detailed expressions for evaluating torsional parameters and determining torsional effects in a range of design situations. This paper focuses on the different design of chassis used in fsae competition and its behaviour when the chassis is employed with front. Abaqus was used as it is a powerful engineering simulation.
Often the torsional stiffness or torsional rigidity of a car chassis is measured. A study on torsional stiffness of the competition gokart. High stiffness improves the responsiveness of the vehicle and allows for more. What is the typical bending stiffness and torsional stiffness. Note all individual drawings will be in a zip file attached as a pdf in the end. Understanding chassis torsional stiffness plays a major role in. If you look around on the web youll find race car chassis design papers indicating torsional stiffness for that particular framemeasurement mode, but they arent comparable to other measurement modes done differently.
In this work, vehicle road load significance of the heavy vehicle ladder type chassis frame torsional stiffness studied, and the two method analysed to obtain. The result shows that the torsional stiffness of the frames with larger kingpin width is better than those with extra members. Pdf methods to determine torsion stiffness in an automotive. There are certain cases when calculated the torsional stiffness of a part might be useful.
This figure is very useful for designing the chassis, and dictates a design that both maximizes stiffness. Mike parzych, product marketing manager at gam explains that torsional rigidity is the ability of an object to resist torsion or in laymans terms twisting, due to an applied torque. Paper open access design and optimization of fsae chassis. While many factors may be involved, coupling torsional rigidity is very important to machine designs as. Design and analysis of space frame chasis for formula student.
Pdf chassis torsional rigidity analysis for a formula. Optimization of heavy duty truck chassis design by. There are several reasons for which high chassis stiffness is preferable. There are several types of heavy duty truck chassis that used in malaysia and no information about the. Aug 28, 2016 with respect to tyre profile i doubt the citroen 2cv or renault 4 had much torsional stiffness given how light they were but they had very long travel, low rate suspensions too. The term chassis stiffness or rigidity generally indicates resistance to bending or flexing while torsional stiffness indicates resistance to twisting. An integral part of the truck is the chassis frame. Being the main load bearing structure of the truck, wellconditioned design of the chassis frame is paramount to the success of the truck as a whole. Products that are subject to a torsional load often require analysis similar to what we use for bending stiffness. The problem on the chassis is the deflection on the chassis whereas higher displacement will affect the torsional stiffness of the truck. The torsional stiffness is one of the most important properties of chassis that significantly affect its dynamic characteristics such as handling and rollover. Torsional stiffness increases and weight from several competing chassis designs are reported. Torsional stiffness is a suitable property for the comparison of frames.
Some modeling guidelines are presented for both frames in isolation as well as the. The torsional stiffness of the chassis with various combinations of added members in the front clip area, engine bay, roof area, front window and the area behind the roll cage was predicted using. In general, torsional stiffness of the frame should be higher than roll stiffness. Pdf design of a winston cup chassis for torsional stiffness. This project investigates the effects of chassis torsional rigidity on vehicle handling and performance for the university of michigans formula sae racecar with the goal of determining a. But torsional stiffness is given more weightage as the total cornering traction is the function of lateral weight transfers 2. Student 1,2department of mechanical engineering 1,2dypiet pimpri, pune abstractin automotive industry, weight reduction is important and active demand because of payload capacity improvement, fuel efficiency and emission reduction. Best way to test simulation and physical chassis torsional. Since it is a twodimensional structure, its torsion rigidity is lower than other chassis. Its main purpose is to securely carry the determined load under all designed operative situations. Analysis of torsional stiffness of the frame of a formula. Torsional forces are experienced by the chassis because of suspension systems. We simulate and physically test our chassis torsional rigidity by the textbook method of securing the rear and applying a weight to a lever arm secured to the front suspension, all done with solid links.
Pdf chassis frame torsional stiffness analysis ijsrd. The most important key performance indicators were found to be weight, torsional stiffness and the torsional stiffness to weight ratio. In the conventional design procedure the design is based on the strength and emphasis is then given to increase the stiffness of the chassis. Stiffness is the resistance of the frame to torsional loads. Methods to determine torsion stiffness in an automotive. Nov 05, 2014 archives for torsional stiffness guest blog. Torsional stiffness does not affect the lateral acceleration of the car, yaw and other properties at steady state turns. Proceedings of the allunion sciencetechnology conferenceproblems of mechanical fatigue in russian, moscow, 1965. Torsional stiffness of the frame has no fixed value with respect to the roll stiffness of the suspension, which should be exceeded. This figure is very useful for designing the chassis, and dictates a design that both maximizes stiffness and reduces weight. Lack of chassis torsional stiffness affects the lateral load transfer distribution, it. This of course assume sthat you test technique is correct, it is easy. The chassis frame is the backbone of a heavy commercial vehicle hcv. Studies have been carried out to investigate the effects that the torsional stiffness resistance to distortion about the longitudinal axis of a vehicle chassis has on.
Apr 03, 2007 because there is no absolute method of making the measurement. Normally the chassis are designed on the basis of strength and stiffness. The formulation is restricted to the torsional analysis of open section thinwalled beams. Reduction of the chassis frame weight represents one of the keys to reaching this goal, but. The total stiffness of the chassis can be found out by, the stiffness of the cockpit is an important component as safety comes first. Teams evaluate the torsional stiffness of the frame to determine the designs quality and find out whether the frame is rigid enough compared to the roll stiffness of the suspension. Figure 29 fully assembled torsional stiffness measuring device on the 2015 fsae chassis. Thus, it should be rigid enough to withstand the various forces acting on it. I want to know how to calculate torsional stiffness of a structure when applying t torque. According to these sources, torsional stiffness should. The resulting data can be analyzed to study the linearity of the torsion stiffness function. The mock up chassis has now become a prototype chassis see photo sf front, and although several of the tube joints are not properly made, some tube sizes are still to be decided, and all the joints are only partially welded, i conducted a torsion test of the chassis see photo torsion test.
The torsional stiffness of several chassis was compared together with the weight comparison in order to get the best design of chassis that has high torsional stiffness and low weight. In automotive industry, weight reduction is important and active demand because of payload capacity improvement, fuel efficiency and emission reduction. The considered cantilever beam, of the length l is subjected to the constrained torsion because of the fact that its one end is fixed and the other free end is loaded by a concentrated torque m. Computational analysis and optimization of torsional. It is usually measured in units of nmdeg or lbftdeg. It comes in many con gurations, where the needs of the customer are re ected in the payload that the frame is tted with and what combination of driving condition and speed it. The major area of concern in the truck chassis was structural resonance at 52 hz, experienced during the torsional and bending modes. Fea was used to analyze the torsional stiffness of the chassis. Torsional stiffness of a tractortrailer chassis springerlink. Torsional stiffness measuring device washington university open. The objective of this study was to develop a stiffness model to select an optimum cross section with determined torsional stiffness. Torsion stiffness is an important characteristic in chassis design with an impact on the ride and comfort as well as the performance of the vehicle 5,6,10. Chassis rigidity is found to decrease exponentially with increasing torsional stiffness.
What is the typical bending stiffness and torsional. Torsional stiffness and natural frequency analysis of a formula sae vehicle carbon fiber reinforced polymer chassis using finite element analysis manuel herrmann finite element is used to predict the torsional stiffness and natural frequency response of a fsae vehicle hybrid chassis, utilizing a carbon fiber reinforced polymer sandwich. Pdf chassis frame torsional stiffness analysis semantic scholar. Reduction of the chassis frame weight represents one of the keys to reaching this goal, but requirements on chassis frame stiffness generally make any weight reduction difficult. Torsional stiffness of chassis frame is necessary to overcome the various load coming on it due to the uneven road surfaces, road camber, loads while negotiating a turn etc. Optimization of torsional stiffness for heavy commercial. Computational analysis and optimization of torsional stiffness of a formulasae chassis 2014010355 one of the key aspects of designing a race car chassis is torsion stiffness roll stiffness. So the chassis seldom took the pounding from the tyres that modern. Adequate torsional stiffness is required to have good handling characteristics. Pdf chassis frame torsional stiffness analysis semantic. The problem of finding the compromise between stiffness and. This of course assume sthat you test technique is correct, it is easy to get big errors in this test both in real life and fea. Based on the simulation result, the multi holes model is the best design due to the highest of torsional stiffness and the lowest mass.
Methods to determine torsion stiffness in an automotive chassis. Much effort has been made to predict the torsional stiffness of alternative winston cup chassis designs using finite element analysis fea 3,4,5,6. This led to the conclusion that, having a torsional stiffness of more than 3 times the roll stiffness, easily adds more. For one, in order calculate the natural frequencies of a part you need to determine the stiffness of the part. Pdf torsional stiffness improvement of truck chassis. Pdf chassis frame torsional stiffness analysis ijsrd journal.
Chassis torsional stiffness jig final design report by raymond deng. Designers strive to develop a chassis design with a high value of roll stiffness to counter the forces applied by the suspension during cornering while. A sample simulation is performed using finite element analysis fea. The more sources one looks for, the more recommendations one can find 25. This model examines the frame and overall chassis torsional stiffness relative to the suspension spring and antiroll bar rates. For performance cars this stiffness number is very important. One of the primary customer wants defined for the chassis is a high stiffness to weight ratio. To obtain good handling performances in the vehicle all we need is the optimum torsional stiffness with lightness in weight and accurate weight distribution along. With respect to tyre profile i doubt the citroen 2cv or renault 4 had much torsional stiffness given how light they were but they had very long travel, low rate suspensions too. I want to know how to calculate torsional stiffness of a structure when applying t torque, i want also to know how to get it as kn. A finite element model is next developed to enable the analysis of different frame concepts. It is universally recognized that torsional stiffness is one of the most important properties of a vehicle chassis, 1. Daniel, similarly to the reply to your other thread, the yield stress and uts of the material do not affect its behaviour in the linear, elastic region i. On the other hand if you want to determine the angle of twist of an object that is made out continue reading torsional stiffness.
The section with the maximum torsional stiffness was used for framelevel optimization to improve the torsional and lateral stiffness of the overall chassis frame. The bending stiffness is usually numerically smaller than the torsional stiffness in those units. Empirical determination fo the chassis torsional stifness. With this in mind the goal of design is to increase the torsion stiffness without significantly increasing the weight of the chassis. Design, analysis and testing of a formula sae car chassis. Section 3 discusses the design of beams for combined bending and torsional effects, principally in relation to straight i section beams. Specifically, the one with width of 828 mm is the best type of frame, and the torsional stiffness is 31. The main disadvantage of the ladder frame is its low torsional rigidity. Using torsional stiffness to measure torsional rigidity in. This project investigates the effects of chassis torsional rigidity on vehicle handling and performance for the university of michigans formula sae racecar with the goal of determining a chassis stiffness design target. The torsional stiffness of each frame type is determined and compared with each other. Torsional analysis of open section thinwalled beams.
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