Analysis of collision performance of anticollision box made of steel–polyurethane sandwich plates

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Highlights

  • A new type of bridge pier anti-collision box was researched.

  • This anti-collision box has a special shape, and it is easy to deflect a ship's bow to avoid violent frontal collision.

  • The impact force of the anti-collision box and the pierand the energy absorbed by various parts of the system were studied.

Abstract

A finite element collision system model was established by using ANSYS/LS-DYNA for a new type of bridge anticollision device with stiffeners made of steel–polyurethane sandwich plates. The model is composed of the anticollision box, the bridge pier, and the ship. In this paper, a numerical dynamic calculation method was used to calculate the impact force of the box and the pier column, the collision depth of the ship, and the energy absorbed by various parts of the system in the most unfavorable frontal collision condition. Then, the influence of the different types and numbers of stiffening ribs on the anticollision performance of the system was analyzed, so as to properly arrange the stiffeners inside the box. The result shows that this kind of anticollision box can effectively protect the pier. When a frontal collision occurs, it can absorb >70% of the impact energy, while the pier only bears <10% of the impact energy. Among the various components of the anticollision box, the outer steel plate of the sandwich plate absorbs the most energy, and the inner steel plate absorbs the second most. The effect of setting the horizontal stiffeners on the impact force, impact depth, and absorption energy of each part of the system is larger than that of the vertical stiffeners, and the effect of improving the rigidity of the anticollision box is also better.

Introduction

A steel–polyurethane sandwich plate is a kind of composite sandwich structure made of upper and lower steel faceplates with a polyurethane core layer firmly bonded between the faceplates [1,2]. This two-layer structure of high-strength faceplates separated by an elastic core layer means that the faceplates are mainly subjected to impact and the sandwich layer mainly receives and transmits shear force, thereby consuming more impact energy [3,4]. The steel–polyurethane sandwich plate structure was first used in shipbuilding and repair and was subsequently used in the repair of steel bridge decks [[5], [6], [7], [8]], and it has been studied for use in explosion-proof structures [9,10].

In the past, the anticollision device of piers relied on itself to absorb energy to achieve the purpose of collision avoidance, this is a passive anticollision method that easily causes damage to the anticollision device. A composite anticollision box constructed with a steel–polyurethane sandwich plate is proposed in this paper. This is a new type of anticollision device that has obtained invention patents in China in recent years,such a device is suitable for bridges on inland waterways, and it has the advantages of high strength, high rigidity, light weight, good formability, and strong impact resistance compared with the traditional anticollision box [[11], [12], [13]]. The more prominent feature is that the circular curved box can rotate around the center point during collision, making it is easier to deflect a ship's bow to avoid violent frontal collision [14,15], with the most of the ship's kinetic energy remaining with the ship, this is an active collision avoidance method that minimizes damage to piers, ships and anticollision devices. Generally, when the ship's tonnage is less than 1000 tons, the bridge pier anticollision box made of a steel–polyurethane sandwich plate can meet anticollision performance without setting stiffeners in the box by properly adjusting the thickness of the sandwich plate. In this way, the amount of steel and welding work, as well as the box weight, can be effectively reduced, and the box can float up and down with the fluctuation of the water level, and this type of anticollision box has been researched and applied in recent years [16]. When the ship's tonnage exceeds 1000 tons, it is usually reasonable to increase the size of the box or properly set stiffeners inside the box. However, if the static load is used to calculate the collision between the bridge and the ship, the effects of dynamic loads may be greatly underestimated [17]. This study is to explore the dynamic performances of this anticollision box with internal stiffeners.

The following finite element collision system model including a ship hull, a box made of a steel–polyurethane sandwich plate, a rubber fender, and a bridge pier was established by using LS-DYNA software, and the numerical dynamic calculation was performed to obtain the dynamic time history curve of the impact force, impact depth, and energy change under the most unfavorable frontal collision. The influences of different types and quantities of stiffeners on the collision energy conversion during frontal collision of the sandwich plate anticollision box were analyzed to properly arrange stiffeners inside the box. Similar studies have been conducted on oblique collisions in which there are more collision opportunities.

Section snippets

Structure of the anticollision box

The shape and structure of this anticollision box is different from that of a conventional anticollision box. The box has a circular shape and a curved outer surface to make it easier to deflect a ship's bow, and the cross section of the box is oval to increase the rigidity of the box and make the box as high as possible above the water surface, as shown in Fig. 1, Fig. 2, Fig. 3. The following is an example to discuss the collision performances of this type of anticollision box.

Taking a

Calculation results and discussions

The frontal collision calculation of the ship was performed for the collision system shown in Fig. 7. The box structure and its internal total of 3 stiffeners were set in a horizontal direction, at up and down intervals of 100 mm, symmetrically arranged at half-height positions of the box, and the oval vertical stiffeners were placed every 30° in the circumferential direction, for a total of 12, as shown in Fig. 4. The ship speed, impact depth, impact force, and energy conversion process of

Effect of stiffeners on the anticollision performance of the box

To discuss the influence of stiffeners on the anticollision performance of the box, we compared and analyzed the various performances by changing the number of horizontal and vertical stiffeners.

Conclusions

In this paper, we analyzed the influence of a different number of stiffeners inside the box on the anticollision performance of the box in a frontal collision between a ship and an anticollision box. We reach the following conclusions:

  • (1)

    A pier anticollision box made of a steel–polyurethane sandwich plate can absorb 71.2% of the impact energy, and the maximum impact energy of the bridge pier is only 6.4%, which indicates that this kind of anticollision box can effectively protect the pier.

  • (2)

    Among

Author statement

Chenglin Shan: conceptualization, resources, data curation, investigation, writing - original draft, writing - review &editing.

Declaration of Competing Interest

I declare that this paper has no relevant conflicts of interest with others.

Acknowledgment

This work is supported by the National Natural Science Foundation of China (Grant No. 51278201).

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