Roll Over and Falling Objects Protective Structures – ROPS and FOPS

Reading Time: 4 minutes

INTRODUCTION

Accidents such as rollovers and falling objects on a vehicle, unfortunately, occur constantly and can lead to physical harm to the passengers. It can be said that some environments are more suitable for such occurrences, such as in a mining plant.  In these environments it is common for mined materials to fall, either during its transportation or even in events like landslides. 

In order to mitigate the risks and reduce the consequences of these claims, many companies need and opt for the installation of auxiliary reinforcement structures, usually inside their vehicles (commercial or off-road), known as ROPS – Roll Over Protective Structure and FOPS – Falling Objects Protective Structure

Understand, through this article, which are the main functions of these structures and learn more about one of KOT Engenharia’s success cases in the analysis of a protection system.     

Figure 1: Illustration of a truck rolled over [1].

ROPS

Targeting the increased internal safety in the vehicle’s cabin, the ROPS concept was created. This structure has the objective of preserving  the operator’s cabin in case a roll over accident takes place involving a car, truck, construction or mining vehicle, etc.

Figure 2: Broken tree fallen over a parked car [2].

FOPS

On the other hand, FOPS has the main objective of ensuring the safety of the machine and vehicle operators in case of an accidental object displacement. These elements can consist of rocks, tree branches, logs, among others. 

CASE STUDY

Aiming to comply with its client’s request, KOT has developed an internal structure project for ROPS and FOPS for a commercial pickup. The concept tried to respond to the requirements declared by the Brazilian Regulation for roll over protective structures, the NBR-03471 [3] and the ISO 3449 [4], which establish application criterion for protective structures against falling objects.

The first stage of the project development was the computational modeling of the cabin, accomplished using software like SolidWorks, FEMAP and LS-DYNA. The ROPS was projected based on some preliminary definitions and the initial concept can be seen on Figure 3.

Figure 3: CAD sketch of the ROPS in lattice pattern [1].

Following these definitions, the initial selection of the transversal section of the pipes used was accomplished after a model elaborated in barred elements. The yield limits were defined considering the failure criteria by a von Mises flow. Figure 4 represents the highest yield found after the application of the loads in accordance with the regulation.

Figure 4: von Mises’ yield criterion for ROPS [1].

With the intent of enabling the assembly of the ROPS in the cabin of the original vehicle, the project established the use of under-assembly, as can be seen in Figure 5.

Figure 5: Assembly diagram of the ROPS [1].

For the protection from falling objects the same roll over protection analysis was carried out, and for the new structure the same ROPS verifications took place.  

Figure 6: von Mises’ yield criterion for ROPS and FOPS [1].

The material considered in the analysis for the cabin structure was a bilinear elasto-plastic behaving steel. This result is in accordance with the characteristics obtained from the technical literature in regards to structural steel for bodywork and complementary data provided by the producer.

The next stages of the project revolved around the realization of simulations with lateral, vertical and longitudinal loads, as defined in the regulations in place. All the virtual tests were approved, thus qualifying the ROPS and FOPS for use. 

The projected structure aligns its structural performance for the loads to which it can be subjected during the event of an accident, as well as presenting geometric compatibility so that there is no interference with the truck’s original cabin structure. Implementing this type of structure can reduce the consequences of a disaster and, in the same proportion, reduce the risk of fatalities.

Conclusions

By reading this article, it is possible to conclude that the engineering knowledge can also be used in the mitigation of fatalities in the event of accidents. KOT has the knowledge needed to apply it, being also able to evaluate different operation contexts and contribute to the results.

Get in touch with KOT’s specialists team!

KOT Engenharia’s Team

With over 27 years of history and various services provided with excellence in the international market, the company promotes the integrity of its clients’ assets and collaborates in solutions to engineering challenges. For this integrity, it uses tools for calculation, inspection, instrumentation and monitoring of structures and equipment.

References:

[1] KOT Engenharia’s archives

[2] Jin, Michael (2020). Disponível em: <https://unsplash.com/photos/mCj7atG0nEc>

[3] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 03471: Máquinas Rodoviárias – Estruturas Protetoras Contra Acidentes Na Capotagem – Ensaios de laboratório e Requisitos de Desempenho. 1999.

[4] Norma Mercosul. NM ISO 3449. Máquinas rodoviárias – Estruturas protetoras contra objetos cadentes – Ensaios de laboratório e requisitos de desempenho (ISO 3449:2005,IDT)

Leave a Reply

Your email address will not be published. Required fields are marked *