Browse Topic: Rollover protective structures
Off-road trucks, tractors and earth-moving machines are at high risk of accidents involving falling objects or rollovers. Therefore, these machines need proper protective structures to protect operators. This study investigates the crashworthiness optimization of a hydraulic excavator cab roof rail based on an improved bi-directional evolutionary structural optimization (BESO) method considering two different load cases (a lateral quasi-static load and an impact load from the top of cab, respectively). In the crashworthiness optimization problem, a weighted summation of external works done by the two different load cases is treated as the objective function while the volume of design domain is treated as the constraint. A mutative weight scheme is proposed to stabilize the optimization and balance the two load cases. Finite element (FE) model is established and two prototypes are fabricated based on the optimal design. Explicit FE analysis is used to predict the performance of roll-over protective structure (ROPS) and falling-object protective structure (FOPS) under standardized laboratory test. The smooth evolution histories of reaction forces demonstrate the effectiveness of mutative weight scheme. The simulation-based test results for the ROPS and FOPS have a close agreement with the experimental test results. The accuracy and efficiency of the FE analysis are high enough to predict the behaviors of ROPS and FOPS under the laboratory tests.
Tractor weight transfer is the most common farm-related cause of fatalities nowadays. As in India it is getting mandatory for all safety devices across all HP ranges. Considering any changes in the weight from an attachment such as Rops, PTO device, tow hook and draw bar etc. can shift the center of gravity towards the weight. center of gravity is higher on a tractor because the tractor needs to be higher in order to complete operations over crops and rough terrain. Terrains, attachments, weights, and speeds can change the tractor’s resistance to turning over. This center of gravity placement disperses the weight so that 30 percent of the tractor’s weight is on the front axle and 70 percent is on the rear axle for two-wheel drive propelled tractors and it must remain within the tractor’s stability baseline for the tractor to remain in an upright position. In our present study formulating the prediction of tractor CG by using a modified excel spreadsheet package employing the parameters of the model, tractor CG were then determined. Finally, the effects of changes in the parameters of the model were evaluated and results of the analyses indicate the changing the tractor CG about the x-axes and y-axes have an influence on the weight distribution of the tractor from front and rear wheel, whereas increasing the tractor weight percentage on the front wheel have an benefit of tractor less lifting on the front end.
An All-Terrain Vehicle (ATV) as defined by the American National Standards Institute (ANSI) is a vehicle that travels on low pressure tires and with a seat that is straddled by the operator, along with the handlebars for steering control. A roll cage can be defined as a skeleton of an ATV. It forms a structural base and 3-D shell around the driver. In case of impacts and roll over incidents, the roll cage is responsible for the protection of driver. The objective is to design, analyze and optimize the roll cage under a set of particular rules given by Society of Automotive Engineers (SAE). The static analysis is carried out using CATIA V5 software for different collisions like front, side, rear and roll over. The main objective of the analysis is to obtain a roll cage enough strong to bear such adverse conditions as well as light in weight for better performance. The safety of roll cage can be ensured by obtaining optimum factor of safety.
Tractor roll over is the most common farm-related cause of fatalities nowadays. ROPS (Roll-Overprotective Structures) are needed to prevent serious injury and death. It creates a protective zone around the operator when a rollover occurs. In India the ROPS is getting mandatory across all HP ranges except narrow track. In the present study states the customized ROPS application for configurable design such as Automated safety zone for all homologation standards, ROPS A0-D excel calculator for selection of material at concept stage and bolt calculator for selection of size. For the above applications below aspects need to consider such as Tractor weight, Rear housing mounting, Operator seat index position (SIP), Seat reference points (SRP) and all ROPS homologation standards. This ROPS application is to reduce the timeline, manual error and ensure the reliability of the modular optimal design for various platforms and variants. Nowadays it is important to perform configurable design at the concept design phase across variants/platform wise including all individual parts (both assembly & child part) so that we can optimize the varieties of material and thickness used, which will reduce the development & validation cost and shorten the time-to-market in later stages. Stochastic design optimization is then performed to reduce the weight of ROPS and ensure the robustness with reliability of the modular optimal design also in this paper. A ROPS design application is an example to demonstrate the proposed methodology by using NX10 - Automation, MathApps for bolt Calculator and ROPS A0-D excel calculator for determine the energy absorption capacity of the ROPS. Application results provide us the review and feedback on the safety and rigidity of the optimized ROPS for different platforms.
This paper discusses a simplified analytical/experimental method for evaluating and designing large buses and motor coaches for rollover protection. The proposed method makes use of the work-energy principle in analyzing the energy-absorbing capacity of the roof and sidewall structure of the vehicle. The basic structural unit is treated as a nonlinear, elastoplastic, 4-bar linkage, with the links connected at hinge points. During rollover, the deformation of the structure is focused at these hinge points and energy absorption is achieved through plastic bending and rotation of the hinge material. The proposed method allows the evaluation and design of these plastic hinges to achieve the energy-absorbing requirements for the vehicle. This paper demonstrates the proposed methodology by evaluating an exemplar large bus design against the European ECE-R.66 rollover design standard. This same vehicle was similarly evaluated in a referenced study, using the finite element analysis (FEA) method. The objective of both studies was to determine a minimum weight solution for the vehicle structure. The minimum weight solution must satisfy both the minimum energy absorption requirements and the structural deformation limitations placed on the design by the ECE-R.66 standard. Both a baseline design and an optimized (minimum weight) design were evaluated in this study. The baseline design served as a reference point in determining the weight-saving potential for the vehicle. The FEA results show a weight-saving potential of 78 kg (172 lb) while the simplified, 4-bar linkage model gives a slightly heavier design with a weight-saving potential of 34 kg (77 lb), indicating that the proposed method of analysis is slightly conservative compared to the FEA method.
Finite Element Analysis (FEA) is a numerical method to find solutions to real world problems and is now commonly used for product development. Various finite element analyses are performed to validate the system performance. Many finite element codes are also available for this purpose. Now-a-days, product development not only deals with the validation of design performance, but also focuses on design optimization. Methods such as one-factor-at-a-time (OFAT) experiments are generally used in which one input factor is varied at a time and its effect on system performance is studied. Design of Experiments (DOE) is a systematic approach in which more than one input factors are purposefully varied to study their effect on system performance. Finite Element Analysis and Design of Experiments approach can be used in combination for design optimization. This paper deals with the process for design optimization that can be followed using FEA and DOE in conjunction. This methodology is explained with an example of structural optimization of rollcage having an objective to minimize the mass of rollcage structure. A finite element model is built and different simulations are performed as required for the DOE study. A screening DOE is performed to discard the unnecessary variables and then a detailed DOE study is performed. Correlations and interactions are extracted from the study to find the relationship between design variables and responses. Inferences are drawn based on these relationships and various designs are made. The optimized design is thus reached and a mass reduction of 22% is achieved.
This SAE Standard applies to an overhead cover installed on a protective frame or enclosure conforming to SAE J2194 or alternately SAE J1194 and the following additional requirement of a drop test to verify the effectiveness of the overhead cover in protecting the operator from falling objects. The test procedures and performance requirements outlined in this document are based on currently available engineering data.
Roll-over protective structures (ROPS) are safety devices which provide a safe environment for the tractor operator during an accidental rollover. The ROPS must pass either a dynamic or static testing sequence or both in accordance with SAE J2194. These tests examine the performance of ROPS to withstand a sequence of loadings and to see if the clearance zone around the operator station remains intact in the event of an overturn. In order to shorten the time and reduce the cost of new product development, non-linear finite element (FE) analysis is practiced routinely in ROPS design and development. By correlating the simulation with the results obtained from testing a prototype validates the CAE model and its assumptions. The FE analysis follows SAE procedure J2194 for testing the performance of ROPS. The Abaqus version 6.12 finite element software is used in the analysis, which includes the geometric, contact and material nonlinear options. Simulation results such as plastic deformation and energy absorption during the sequence of loading conditions were compared with the results of prototype testing. Reasonably good correlation was observed between the experimental and FE results, which shows that the FE model is validated against the experimental model.
Problem-plagued effort last year spurs Baja SAE team from VIT University of India to overhaul itself and its car. THIS ARTICLE ISN'T A THRILLING DISCOURSE ABOUT ENGINEERING INNOVATION and game-changing technology. It most definitely isn't a dramatic rags to riches story. Neither is it a satirical piece on the often erroneous experiments that make Baja SAE a fantastic platform for students to learn and thrive in the automotive industry. Rather, this story is the firsthand account of how a Baja SAE team from India with international ambitions is turning its fortunes around through a complete perspective change, calculated risk-taking and, of course, a touch of luck.
Within the exploration and resources sector some companies have required the fitment of Roll Over Protective Structures (ROPS). The issues with respect to: no ROPS, internal ROPS or external ROPS are discussed. The practical experience of designing, testing, fitting external ROPS in southern Africa are detailed as well as the investigation and analysis of a number of rollover crashes of vehicles fitted with the external ROPS and injury outcomes are compared with USA rollover injury data.
A cabin on an agricultural tractor is meant to protect the operator from harsh environment, dust and provide an air conditioned space. As it is an enclosed space, cabin structure should be a crashworthiness structure and should not cause serious injury to operator in case of tractor roll over. There are International standard like OECD Code 4, SAE J2194 which regulates the crashworthiness of this protective structure. The roll-over protective structure (ROPS) is characterized by the provision of space for a clearance zone large enough to protect the operator in case of tractor overturn. None of the cabin parts should enter into the clearance zone for operator safety. In addition to meeting ROPS test criteria, the cabin structural strength should be optimized for the required tractor life. In this paper, simulation process has been established to design an agricultural tractor cabin structure and its mountings to meet the above requirements. A Design Verification Plan (DVP) has been developed consisting of 3 load cases. Loads and boundary conditions have been arrived at based on the OECD Code 4 and road & field excitations. Design acceptance criteria have been formulated for clearing the ROPS test and durability for the tractor life. Virtual validation has been done by performing (i) A non-linear elasto-plastic simulation in ABAQUS for ROPS test and (ii) Static & modal analysis in MSC Nastran for durability. For ROPS test, equivalent plastic strain approach has been used for predicting the crack initiation and for durability analysis, fatigue based approach has been used for predicting the life. Lab test has been done for the ROPS test and has been correlated with CAE results. At the end, further design iteration has been done for mass and cost reduction. Biggest challenge in this work was to meet the above criteria within the constraint of material availability and manufacturing limitation.
A number of performance and safety related aspects of motorsports have begun to receive increased attention in recent years, using the types of engineering analysis common to other industries such as aerospace engineering. As these new engineering approaches have begun to play a larger role in the motorsports industry, there has been an increase in the use of engineering tools in motorsports design and an increase in the inclusion of motorsports in the engineering education process. The design, modeling, and analysis aspects of a recent project examining the design of roll cages for American short-track open-wheel racing cars will be discussed in this paper. Roll cage structures were initially integrated into cars of this type in the 1960s. Countless lives have been saved and serious injuries prevented since the introduction of cages into these types of cars. However, the general configuration of these cages has not seen significant change or improvement in the four decades since their introduction. Crash tests conducted in the past two years have demonstrated the potential for the driver's helmet to impact an external barrier and also indicated that some tubes and joints in the cage structure may be excessively loaded in certain crash scenarios. Recent innovations in engineering design techniques involving the utilization of Three Dimensional (3D) Finite Element Modeling (FEM) and Finite Element Analysis (FEA) have opened opportunities for engineering analysis which could improve the design of these roll cages. This paper will discuss how the motorsports engineering students and faculty of the Motorsports Engineering program at Indiana University Purdue University Indianapolis (IUPUI) have utilized traditional research, modeling, and analysis approaches from academia to assist in the design of new aspects of competition vehicles aimed at increasing safety.
Different roof strength methods are applied on the 2003 Ford Explorer finite element (FE) model to achieve the current Federal Motor Vehicle Safety Standard (FMVSS) 216 requirements. Two different modification approaches are utilized. Additionally, the best design of each approach is tested dynamically, in rollover and side impact simulations. In the first approach, several roll cage designs are integrated in all pillars, roof cross-members, and in the side roof rails. A roll cage design with a strength-to-weight ratio (SWR) of 3.58 and 3.40 for driver and passenger sides, respectively, with a weight penalty of 18.54 kg is selected for dynamic test assessments. The second approach investigates different localized reinforcements to achieve a more reasonable weight penalty. A localized reinforcement of the B-pillar alone with a tube meets the new FMVSS 216 requirements with a weight penalty of 4.52 kg and is selected for dynamic analyses. The two selected reinforcement designs are tested in a dynamic unconstrained rollover crash under different pitch angles while using common rollover initial conditions. Based on the limited dynamic analysis, the localized reinforcement has proved to be an effective approach for front row seat protection. However, passengers in the rear seats are better protected by the roll cage solution. Additionally, side impact analysis is examined for both approaches. Overall, the influence of both reinforcement methods on the side impact is small and therefore deemed acceptable. These methods can be incorporated in vehicle's roof structure or taken into consideration for future vehicle designs.
One of the most common events of injuries and deaths in mining activities is the vehicle rollover, for example, the rollover of pickup trucks used to carry freight and workers through this environment or out of it. One way to prevent these fatalities is the use of rollover protective structures (ROPS) which are safety devices fitted internal or externally to vehicles in order to provide protection to driver and passengers during an accidental rollover. The design of these devices is quite complex since it must be carried out analytical and numerical analyses and finally experimental tests. This latest is destructive and expensive since it is necessary a specific apparatus mounted in a large test field. The most widely used test for rollover in the automotive industry is the FMVSS-208 (U.S. Government) or SAE J2114-2011. In order to save time and reduce cost with prototypes this paper deals with modeling and simulation of a rollover dolly test of a pickup truck model according to the above cited regulation using the nonlinear finite element method (LS-DYNA® software). The aim is to execute an analysis of the energy involved in the rollover process contemplating both kinetic and impact energy using the virtual model. The outputs of this model: internal (stored) energy due to impact and translational velocity of the CG vehicle were accomplished to provide input information for use in future work in virtual rollover tests with ROPS.
The purpose of this SAE Information Report is to provide concepts for rational selection and application of materials for Rollover Protective Structures (ROPS) and Falling Object Protective Structures (FOPS) and to provide information about the properties that should be considered in selecting and utilizing material in protective structures. While other materials could conceivably be used successfully, this report is limited to a consideration of steel with discussion on its mechanical properties and processing characteristics. Emphasis is placed on the toughness aspect (ability to resist brittle fracture) as this property is of paramount importance to structure integrity. It is emphasized that specific values for material properties have relevance to performance only in conjunction with specific design considerations such as structure size or weld joint detail and location. Because there are many design-material systems which can be successfully employed to achieve the prescribed performance of protective structures, this report does not make categorical selection of steels.
Over the last twenty years, large improvements in occupant safety have been made in NASCAR®'s (National Association for Stock Car Auto Racing, Inc.) racing series. While proper occupant protection requires both occupant restraint and preservation of sufficient occupant survival space, this study is focused mainly on the latter of these two necessities. The NASCAR tubular vehicle chassis has evolved through the years to provide improved protection for the driver in rollover incidents. The chassis has continued to progress over time to improve its strength as unique crashes sometimes highlighted opportunities for advancement. Recent enhancements tested using computer modeling, quasi-static testing, and full scale drop tests have improved the roof structure of the stock car chassis. These improvements have been incorporated into the 2013 NASCAR Sprint Cup and Nationwide Series cars.
Rollover Protective Structures (ROPSs) are used in off-highway vehicles to protect operator in case of accidents involving overturning of vehicle. The role of a ROPS is to absorb the energy of Rollover without violating the protected operator zone. The performance of a ROPS is determined by its ability to absorb energy under prescribed loading conditions. The performance depends upon design parameters, such as tube thicknesses, material grades, ROPS tube cross-sections, etc., that define the structure. In this paper, we describe a method that uses Design of Experiments (DOE) to determine the correlation between the performance of a ROPS for a small tractor and its critical design parameters. The correlation results are discussed for two types of loading conditions, namely “front push loading” and “side push loading”. The correlation obtained is further used to identify the optimal design parameters for maximum energy absorption under constraints on allowable deflections.
This SAE Standard applies to General-Purpose Industrial Machines described in Category 2 of SAE J1116, but excludes skid steer loaders (covered by SAE J1388). Protection for the operator of an attachment (for example, a backhoe) is excluded from the scope of this document.
Items per page:
50
1 – 50 of 195