Rollover Protective Structures Research Articles

Optimal design of earth-moving machine elements with cusp catastrophe theory application

This paper deals with the optimal design problem solution for the operator of an earth-moving machine with a roll-over protective structure (ROPS) in terms of the catastrophe theory. A brief description of the catastrophe theory is presented, the cusp catastrophe is considered, control parameters are viewed as Gaussian stochastic quantities in the first part of the paper. The statement of optimal design problem is given in the second part of the paper. It includes the choice of the objective function and independent design variables, establishment of system limits. The objective function is determined as mean total cost that includes initial cost and cost of failure according to the cusp catastrophe probability. Algorithm of random search method with an interval reduction subject to side and functional constraints is given in the last part of the paper. The way of optimal design problem solution can be applied to choose rational ROPS parameters, which will increase safety and reduce production and exploitation expenses.

A survey on fatal accidents for overturning of agricultural tractors in Italy

The government agencies that are responsible for labour safety frequently delay the publishing of the figures of the accidents occurred in agricultural sector, including those caused by the overturning of tractors. This is due to the time required to conclude the investigation of each fatal event. The elimination of this delay may not be possible. Thus, the statistics do not satisfy the requirements of effective surveillance of the trend of overturning accidents to implement prompt actions to increase safety. Many web portals have been created in these last years to support weekly or daily newspapers at the local level. A fatal accident due to a tractor overturning is considered to be a significant occurrence. Thus, from 2008 a web observatory was created to determine the current situation of accidents involving tractors that overturned. This method had a significant advantage for obtaining the trend of the statistics related to the main details of each event practically in real time, such as the age, gender and nationality of the victims; the month, day of the week and location of the accidents and the characteristics of the involved machinery. Eight hundred seventy-three fatal accidents were processed in Italy during the survey period. As expected, the average age of the victims was quite high (62 years old). 68 % of the overturning accidents occurred during field operations, and 32 % occurred during transport operations. Eighty-six percent of the fatal events occurred on slopes, but above all ROPS (Roll Over Protective Structure) protection was missing from 61 % of the involved tractors. In the majority of the cases, the tractors were old machines that did not operate in accordance with general and specific safety labour laws.

ROPS designs to protect operators during agricultural tractor rollovers

Although it is well known that properly used Rollover Protective Structures (ROPS) can virtually prevent agricultural tractor rollover fatalities, the U.S. still has hundreds of these fatalities per year. An estimated 1.6 million tractors are not equipped with ROPS. Many of these tractors do not have ROPS commercially available although they were originally designed to support a ROPS. Some tractors have foldable ROPS that are not used properly. Other ROPS, although meet appropriate performance standards, are not effective at eliminating continuous rolls.To meet this need, a Computer-based ROPS Design Program (CRDP) was developed to quickly generate ROPS designs based on agricultural tractor weights and dimensions. The ROPS designed with the CRDP for the Allis Chalmers 5040 tractor successfully passed the SAE J2194 static longitudinal, transverse, and vertical tests. A simple foldable ROPS lift assist was designed and tested to ease in the raising and lowering of ROPS; decreasing the raising torque from 90Nm to less than 50Nm, while also lowering the resisting torque to lower the ROPS. A model to determine the critical ROPS height CRH based on off-road vehicle dimensions and center of gravity (CG) height was developed and evaluated.

Farm Safety Practices and Farm Size in New South Wales

ABSTRACT Objective: There is some evidence to suggest that safety on small-area farms may not be high priority due to economic constraints and lack of knowledge. This has important ramifications for injury and economic burden. The objective of this research was to conduct a pilot study to investigate whether small- to medium-area farms implement fewer safety practices than large-area farms. Methods: Farmers were recruited from farm safety training days, field days, and produce stores in rural New South Wales (NSW), Australia. Small- and medium-area farms less than 500 ha (1235 acres) in size were aggregated for analysis and compared with large-area farms (≥500 ha) for survey items, including safety equipment owned and used, safety practices protecting children, barriers to improving safety, and causes of injury. Results: Overall, small/medium-area farms were found to own less safety equipment and to employ less safety practices than large-area farms. In particular, fewer tractors were fitted with rollover protection structures, there was less signage, less hearing protection, and fewer machinery guides. Injury rates were slightly less for small/medium-area farms, particularly involving vehicles. Small- and medium-area farmers were more likely to report lack of skills as barriers to making safety improvements. Conclusion: This pilot study found some evidence that small/medium-area farms implement fewer safety practices than large-area farms. A larger study is warranted to investigate this further, with particular focus on barriers and ways to overcome them. This could have important ramifications for government policies supporting struggling farmers on small/medium-area farms.

Developing and evaluating a finite element model for predicting the two-posts rollover protective structure nonlinear behaviour using SAE J2194 static test

This research focuses on applying Non-linear Finite Element (FE) techniques to predict ROPS force-deflection curves under the simulated standardised static tests. The Society of Automotive Engineers (SAE) J2194 ROPS static standard test was selected for this study. According to the SAE J2194 standard, ROPS must be capable of absorbing predefined levels of energy under longitudinal (rear) and transverse (side) load tests before collapsing as well as avoiding large deformations that infringe upon the driver's clearance zone or leave the clearance zone unprotected. A nonlinear finite element approach was used to predict the response of two rear-mount two-post ROPS under simulated side and rear test conditions for Allis Chalmers 5040 and Long 460 tractors. The ROPS were designed with the Computer-based ROPS Design Program using a bolted corner bracket assembly to simplify the ROPS design process. The recommended FE model (ASTM, C3D10M, 0.01) was found to predict the ROPS performance deflection (RPD) with average error less than 10% compared to experimental test measurements. The FE model predicted the ROPS behaviour under rear loads more accurately than under side loads. The developed FE model based on measured stress-strain curves from test specimens was found to predict the ROPS behaviour more accurately than the FE models developed based on the Ramberg-Osgood material model.

Research on a rollover protective technique for a vibroseis truck based on reliability analysis

Rollover accidents occur frequently in the process of vibroseis truck driving, which endangers the drivers and apparatus. Therefore, we first study the driving stability of vibroseis trucks to determine the limit state function of stable driving. Then, the stable driving reliability analysis of the vibroseis truck could be performed under complicated road stimulation. The analysis results show that the risk of rollover still exists, so it is necessary to install a rollover protective structure (ROPS) on the vibroseis truck. Therefore, we establish a systematic and scientific evaluation index system of safety protection and performance. Then, based on the finite element analysis (FEA) technology, we perform the dynamic simulation analysis of vibroseis truck rollover with and without the ROPS. The ROPS would play a significant role in protecting the vibroseis truck. The research results also provide scientific guidance for the similar design of vehicle anti-rollover structure in the field.

Hazard Identification and Risk Assessment for Improving Farm Safety on Canadian Farms.

Agriculture is one of the most hazardous industries worldwide. The number of serious accidents on farms, despite sophisticated technology, development of effective prevention methods, and high-quality training and improved skill levels of farmers, is still very high. The purpose of this study was to develop and apply a generic farm safety protocol to hazards that have been identified in previously published literature and demonstrate the potential benefits of such a protocol with a view to raising awareness of farm safety. Hazards in agriculture were categorized, and literature highlighting the risks associated with hazards was collated. A protocol was developed and applied to establish the likelihood of a hazard causing injury and the consequence of that injury should adverse effects of hazards be realized. The results indicated farm ownership, farm being used as a primary residence, and missing rollover protective structures as the greatest farm risks with expected likelihood and extreme consequence such as death or permanent disablement. Other hazards that require immediate attention while developing mitigation strategies include accident history and existing medical conditions of the farmer, working environment (i.e., alone and isolated), water bodies in the proximity of the farm, lack of periodic machine maintenance, uncovered power take-off and other rotating parts of the tractor, missing safety decals, auger entanglements, and unprotected use of pesticides. Intervention strategies may be guided by considering the results presented in this study. Moreover, farm safety specialists should increase their efforts to promote effective injury prevention methods and enforce safe work environments. The developed protocol addresses almost all common aspects of farming hazards and can be used to mitigate risks associated with hazards in any farm setting.

Stress of dynamic loaded protection cab ROPS of truck

The paper describes the design geometry, calculate deformation, deformation energy and stress safety of extended hydraulically lifted ROPS frame lorry TATRA by FEM according to Australian Standard AS 2294.2-1997 Earth-moving machinery-Protective Structures, Part 2: Laboratory tests and performance requirements for roll-over protective structures and by international Standard ISO 3471: 2008 (E) for the proposed design solution.

The Effect of Speed on Foldable ROPS Actuation Forces.

The number of fatalities caused by tractor rollovers has decreased in recent years, but the number of fatal tractor rollover accidents with a folded-down rollover protective structure (ROPS) has increased. Operating a ROPS-equipped tractor in low overhead clearance zones is difficult and sometimes impossible. The foldable ROPS (FROPS) was designed to solve the rigid ROPS problem, but lowering and raising a conventional FROPS is a time-consuming and strenuous process. After operators fold down a FROPS to pass a low overhead clearance zone, some prefer to leave it in the folded or inoperative position, increasing the risk of a rollover fatality. The actuation forces for raising and lowering a FROPS are not well known and may be influenced by actuation speed. A completely randomized block design with two blocks, five levels of speed, and multiple replications was conducted to investigate the effect of speed on actuation torque. The blocks were two sizes of tractor FROPS. The test included five levels of speed, including two levels of static measurement and three levels of dynamic measurement. A variable-speed motor system was used to control the speed for raising and lowering the FROPS. The actuation torque is a function of the FROPS upper part shape, dimensions, material density, turning acceleration, and friction. A theoretical model was developed to predict the actuation torque based on the FROPS shape, dimensions, and material density. For one ROPS, due to friction, the dynamic actuation torque was greater for raising and less for lowering than the theoretical torque. Indicator variable regression was used to analyze the effect of speed on actuation torque. Results showed that speed had a significant (p > 0.05) effect on actuation torque. Although there were statistically significant differences between the dynamic actuation torques, these differences were relatively small and negligible compared to the differences between the static torques.

Narrow-Track Agricultural Tractors: A Survey on the Load of the Hand-Operated Foldable Rollbar.

To protect the driver in case of a tractor overturn, narrow-track tractors (used in vineyards and orchards) can be equipped with a rollover protective structure (ROPS) consisting of a two-pillar front-mounted foldable rollbar. The transition from the horizontal (rest) to the vertical (protection) position of this ROPS is performed manually by the driver. In addition to the time spent performing this task many times each day, a moderate physical load is required, given that these rollbars often have a mass of some tens of kilograms. In practice, neglect and poor attention to safety lead to the foldable rollbar remaining continuously in the rest position rather than being moved to the vertical (protection) position. Several rollover accidents have been fatal for the driver because the tractor, although equipped with a two-pillar front-mounted ROPS, had the rollbar in the horizontal position at the time of the event, thus assuring no protection to the driver. This issue is quite serious. To remove at least one of the problems for the proper management of this type of ROPS, the OECD has recently updated its Code 6 by introducing an optional test addressing the manual handling of front-mounted rollbars, providing a maximum load of 100 N. Several tests were conducted on new rollbars to ascertain the accuracy of this limit. The 100 N value was generally exceeded, which is cause for criticism. Indeed, a more appropriate reference for manual handling in this case would be the higher loads (up to 250 N) already provided by other standards for non-continuous tasks.

Tractor ROPS and Stability Research: Introduction to this Special Issue.

Agricultural production has clearly benefited from the development of the tractor. The tractor provides a traction device and mobile power source. However, operating large equipment with high clearance on uneven ground leads to stability and overturn issues. Around the world, tractor overturns are still a leading cause of agricultural production fatalities. This special issue of the Journal of Agricultural Safety and Health focuses on recent research on tractor ROPS (rollover protective structures) and stability. Engineers and scientists in both Italy and the U.S. have been working on these topics, attempting to solve old problems and address rising issues. Understanding the factors leading to tractor instability, investigating the structures protecting the operator, and examining the continuous roll potential will all lead to increased operator protection and reduced fatalities.

Chores at Times of Fatal or Serious Injuries Associated with Tractor Overturns with and without Rollover Protection

This study describes chores when farmers were either fatally or seriously injured and required emergency medical treatment as a result of overturns of tractors with or without rollover protective structures (ROPS). Data from the 2002 Kentucky Farm Tractor Overturn Survey were used for this study. The data were collected by a telephone survey of a population-based random sample of 6063 (7.98%) of Kentucky’s 76,017 farm operators as listed in the Kentucky Agricultural Statistics Service database. Of farm operators interviewed, 551 (9.1%) reported 603 overturns and 5512 (90.9%) reported no overturns in the history of their farm, covering a period from 1925 to February 2002. Only the latest overturn was considered to improve recall accuracy. In addition, since the 1925 to 1959 time period had only 49 (8.1%) of the overturns reported, (14 farmers did not provide the year of most recent overturn); only data from the 1960 to 2002 period (approximately 41 years) were used. After making these adjustments, incidents evaluated included 25 cases (one fatal and four serious nonfatal injuries) that involved ROPS-equipped tractor overturns and 88 cases (24 fatal and 64 serious nonfatal injuries) that involved non-ROPS tractor overturns. Chores at highest risk for tractor overturns were identified for which educational and ROPS retrofit interventions could be emphasized. The highest frequency of overturn-related fatalities and nonfatal injuries were associated with hay harvesting, rotary mowing, and on-farm travel chores. These three chores represented 68.2% of fatal events and 50.0% of permanent and 56.6% of temporary disability overturn incidents. Tragically, in countries such as India and China with emerging mechanization, a large majority of tractors are produced without ROPS that can be expected to result in the same overturn-related epidemic of deaths experienced in highly mechanized countries, despite evidence of the protection provided by ROPS.

Enhanced non-linear material modelling for analysis and qualification of rollover protective structures

Finite element simulations of a rollover protective structure are an important aspect in its design, as it provides a means of structural integrity qualification prior to the required destructive testing. A good understanding of the rollover protective structure behaviour under simulated loading offers engineering practitioners the opportunity to optimize the design. The testing conditions, which are outlined in the applicable standards, result in plastic deformation of the rollover protective structure, associated with material hardening of various areas of the structure. An accurate description of the material behaviour is important for finite element simulations of the structural response. This research examines some of the hardening models commonly used in simulations of rollover protective structures, which are available in most finite element commercial software, including linear and multi-linear isotropic and kinematic hardening models and non-linear kinematic hardening models. The numerical performance of the plasticity models in representing the material behaviour was compared with the experimental data for commonly used rollover protective structure material. Analysis revealed the potential benefits and drawbacks of the various models. Moreover, a damage-induced softening model was implemented at the structure joints in conjunction with the non-linear hardening models. Enhanced computational results were obtained through this modelling variation, highlighting the importance of material modelling at the primary structure and the joints of a rollover protective structure.

The NIOSH CROPS Demonstration Project: A Study in New York and Virginia with an Emphasis on Youth.

The agriculture, forestry, and fishing (AgFF) industry sector has had the highest rate of work-related deaths over the past several years. Tractors are the single largest source of occupational fatalities in this industry sector, and tractor rollovers are the largest category of tractor fatalities. The risk of death due to tractor rollovers has been found to be reduced considerably when rollover protective structures (ROPS) are used in conjunction with seatbelts. Increasing the number of tractors with ROPS and seatbelts is one way in which tractor rollover fatalities can be mitigated. The NIOSH cost-effective rollover protective structure (CROPS) project was designed as a demonstration project to determine if CROPS, a type of ROPS, could be retrofitted in the field and were acceptable to farmers. To this end, the CROPS project was successful, with 50 tractors being retrofitted with CROPS in the field. All study participants were asked to complete a pretest, test, and posttest regarding the CROPS retrofit demonstration and their knowledge and attitudes toward ROPS. CROPS demonstrators were the participants who retrofitted their tractors with CROPS. Demonstrators were asked to recruit three to five other participants, known as observers, to watch the demonstration. The rationale was to generate interest in ROPS/CROPS among other farmers and community leaders. Overall, 16% of the participants had youth operating tractors on their farms. Participants reported that 44 youth operated tractors on their farms, more than 25% of these young tractor operators were 4 to 10 years old, and half of the youth operating tractors on participant farms were 13 years old or younger. Only one participant group (demonstrators) included individuals who had all of their tractors protected with ROPS/CROPS for young tractor operators (28%), but they accounted for only one farm each among the New York and Virginia demonstrators. The survey question on ROPS importance did not show an overall increase after respondents participated in the CROPS demonstration project. However, one Virginia observer asked to become a Virginia demonstrator and installed a CROPS on his tractor. Additionally, the questions on attitude toward ROPS showed a general increase in mean scores, with the some of the lowest response categories on the follow-up survey not being selected by respondents, indicating a potentially positive impact on participants' safety attitudes toward ROPS. For the safety attitude questions, the majority remained the same. This study indicates there is still much work to be done to reduce the number of deaths in production agriculture due to tractor rollovers. CROPS could be a valuable addition to the efforts of retrofitting ROPS on tractors in order to reduce the number of deaths due to tractor rollovers.

The CROPS Curriculum Experiment: Evaluating the Farm Safety Knowledge Gained Among Secondary Appalachia Youth

Rural youth in poverty stricken Appalachian communities are the highest at-risk population for tractor rollover accidents (Cole, 2007). The Apprenticeship of Observation theory (Lortie, 1975) concludes that the “apprentice” learns from watching those perceived to be the teacher and their work and so mimic their actions. Thus, farm youth who often overlook safety precautions believe farm accidents are simply a way of life. This project was partially funded through the Southeast Center for Agricultural Health and Injury Prevention. The funds assisted in the development of a Cost-effective Rollover Protective Structure (CROPS) curriculum. A total of 54 (N = 54) secondary agriculture mechanics students, served as the treatment group (n = 31) and control group (n = 23). The treatment group received farm safety instruction from their secondary agriculture teacher through the use of the CROPS curriculum while the control group received their farm safety instruction from their secondary agriculture teacher who taught, only, to reach the required state standards. Results from the quasi-experimental design study revealed a statistically significant gain in farm safety practices from the treatment group as compared to the control group. Recommendations to the participants, future participants, and research are also included.

Simulation and Analysis of a Rider’s Risk of being Mechanically Asphyxiated as a Result of a Quad Bike Rollover

From 2001 to 2013, over 181 people have died in quad bike (commonly referred to as All Terrain Vehicles or ATVs in the USA) incidents in Australia; 45% of fatalities are work related and 55% are from recreational use. Quad bikes are the leading cause of injury and death on Australian farms. In 2011 alone, there were 23 quad bike related fatalities and 18 of these occurred on a farm. Deaths due to rollover account for about half of the quad bike fatalities and 90% of rollover deaths occur on farms. The Heads of Workplace Health and Safety (HWSA) Trans-Tasman Working-Party on ‘Quad Bike Safety’ inquired whether it was: “… reasonably practicable for a device to be developed that when fitted to quad bike reduces the potential for death and/or serious injury caused by entrapment beneath an overturned vehicle? ” The options which have been considered to protect riders in the event of a quad bike rollover are: Personal protective equipment; Active riding; Crush Protection Devices (CPD); Roll Over Protective Structures (ROPS) without restraint; and ROPS with restraint. Post rollover entrapment of the torso by a quad bike can result in mechanical asphyxia. 9,600 simulations (6 x 1,600) using PC-Crash were conducted to comparatively evaluate quad bike rollovers which could result in mechanical asphyxiation. The simulations illustrate the effectiveness and benefits of CPD (Quadbar or Lifeguard); ROPS without restraint and ROPS with restraint (Polaris Sportsman Ace) over the basic quad bike in terms of the rider being entrapped beneath an overturned quad bike and mechanically asphyxiated post rollover.

VIRTUAL SIMULATION OF ROPS ON THE CABIN STRUCTURE

Rollover protective structure is an additional safety structure provided to safe guard the driver/occupant operating the heavy machinery, which are basically used in the mining, forests, material handling, agriculture and rural areas operation in non uniform surface, large weight and high center of gravity make this susceptible to dynamic stability. The risk for rollover of earth movers are being increased day by day. Under these conditions the rollover protective system is to protect the occupant and driver. The model of ROPS is created by using CAD software. Meshing is created by using HYPERMESH software. FEA analysis of ROPS is carried by using the ABAQUS software. This paper deals with the energy absorbed by the ROPS during the rollover of a vehicle in different Loading conditions and Deflection of ROPs well within the safe limit accordance to the ISO 3471:2008.

Development of an automatically deployable roll over protective structure for agricultural tractors based on hydraulic power: Prototype and first tests

An inadequate use of the deployable Roll Over Protective Structure (ROPS) in agricultural tractors contributes to fatalities in rollover events. To help to resolve this problem, an automatically deployable ROPS was designed, constructed and tested. The prototype, called HydraROPS, established two assistance levels for the elevation of the foldable ROPS. In the first level, the driver decides to change the ROPS’ position and this change is made using the manual activation on the board. In the second level, an automatic change to the operative position occurs in situations of impending rollover, without the intervention of the driver. In this level, it automatically sends a phone message with the GPS location to contact emergency response personnel. The tractor’s hydraulic power was used to move the protective structure. In order to increase the deployment speed of ROPS, a pressure accumulator was included in the hydraulic circuit. The deployment time of the ROPS without the pressure accumulator was 2.599s and with the pressure accumulator 0.743s. The results of the research show that the pressure accumulator assembled in the hydraulic circuit reduced the deployment time of ROPS by 71%; and that the electronic control system can correctly predict overturn. HydraROPS has the advantage compared to other automatic deployment devices of protective structures that can be installed on tractors equipped with a certified rollover protective structure. The installation in marketable tractor models does not modify the protection structure; therefore a new certification of the protection structure is not necessary.

Advanced design for vibroseis truck's ROPS and its secure and protective performance analyses based on dynamics simulation research

This research develops a design methodology for the vibroseis truck rollover protective structure (ROPS) and analyses its safety and protective performance with dynamics simulations. A new ROPS with the vertical anti-rolling over property is designed. For the typical field working conditions, we perform the stability study on the vibroseis truck and find its threshold function by using rollover dynamics. With the proposed protection and performance evaluation criteria, we analyse the protection performance of the new and old ROPS with finite element (FE) dynamics simulation. Then, the stress to strain, impact deformation, impact acceleration and interior energy distribution law are obtained during the process of the truck rolling over. The effect of the structure on its protective performance is also found. These analyses result in an optimal design of ROPS. The results will improve the safety of vibroseis trucks and then enhance the technology of oil and gas exploration equipment.

A multibody approach applied to the study of driver injuries due to a narrow-track wheeled tractor rollover

This paper proposes the use of the multibody approach to evaluate the severity of the injuries to the driver associated with rollover of an agricultural tractor. A simple rollover accident of a narrow-track wheeled tractor was simulated in the multibody-FEM Madymo environment and the biomechanical damage to the operator with and without 2-point pelvic restraint was analysed. The structure of the tractor was considered to be unbendable, whereas i) infinitely rigid, ii) clay-based and iii) sand-based soils have been studied. The obtained results highlight the important role played by the seat belt in confining the farm operator within the safety volume maintained by the rollover protective structure (ROPS) of the tractor so that the injuries are reduced. The deformation of the soil produces lower acceleration and velocity values than those obtained with a rigid soil. On the other hand, as soil plastic deformations increase, the penetration of ROPS into the soil also increases, thus reducing the safety volume of the tractor and increasing the probability of interactions between the operator and the soil.