WO2023014312A1

WO2023014312A1 - System enabling use of porosity embodiments in passive collision security members in vehicles

Info

Publication number: WO2023014312A1
Application number: PCT/TR2021/051113
Authority: WO
Inventors: Murat YAZICI; Hakki ÖZER; Harun GÜÇLÜ; İbrahim Kürşad TÜRKOĞLU
Original assignee: Bursa Uludağ Üni̇versi̇tesi̇
Priority date: 2021-08-04
Filing date: 2021-11-02
Publication date: 2023-02-09

Abstract

Invention is a system providing enhancement of vehicle collision members performance and comprises crash box (1) enhancing energy absorption nature and having lattice geometry hybrid composite syntactic foam filling, sandwich crash box (2) enhancing energy absorption nature and having lattice geometry hybrid composite syntactic foam multi-layer core, close profile cross-section bumper beam (3) enhancing bending rigidity and energy absorption nature, with auxetic geometry hybrid composite foam material filling, open profile cross-section bumper beam (4) of sandwich structure enhancing bending rigidity and energy absorption nature, having core made from auxetic geometry hybrid composite foam material, anti-intrusion bar (5) enhancing bending rigidity and energy absorption nature, with auxetic geometry hybrid composite foam material filling, anti-intrusion bar (6) of sandwich structure enhancing bending rigidity and energy absorption nature, having core made from auxetic geometry hybrid composite syntactic foam material.

Description

SYSTEM ENABLING USE OF POROSITY EMBODIMENTS IN PASSIVE COLLISION SECURITY MEMBERS IN VEHICLES

The Field of the Invention

Invention relates to a system providing enhancement of performance of vehicle hitting members.

Invention relates to vehicle collision members with improved collision performance filled with hybrid composite syntactic foam structures made from syntactic foam basis core structures reinforced with short fibres and filled with such foam structures and designed as Meta materials.

Background of the Invention

Today improving automotive industry conducts various studies to achieve new emission values. Primary one of them is to reduce weight. Conventionally lighter materials having the same strengths can be used instead of parts made from metal materials. For this purpose, metals having high strengths, foam filled sandwich embodiments, composite materials are alternative options thereof.

Today motor vehicles are inevitable transport vehicles. Traffic accidents occur due to various reasons such as carelessness, driving under alcohol, travelling at over speeding speeds etc. Although measures against such accidents are taken, life and property loss occur. Therefore, active and passive security measures are needed.

Basic duty of collision members in vehicles is to minimize stroke effect and elastic wave occurring during collision on the vehicle and passenger. In such cases, it is targeted to absorbed kinetic energy of vehicle in balanced and continuous way. Security members of vehicle for front collision: bumper beam and crash box. Basic duty of bumper beam is to minimize effect of front hitting of vehicles (collision with another vehicle, hitting rigid barriers, poles or trees and similar objects not having cutting effects etc.) on passengers and drivers inside vehicle life cabinet (inside vehicle) such as threatening to life, injury, or danger by absorbing them. In case of front collisions of vehicles, basic safety members are collision safety members provided inside the door. This member is called anti intrusion bar. It functions as absorbing hitting energy in case of side hitting with door and prevents damage to passenger or driver. In both cases safety members are preferred as members in form of open or close cross-section profile or pipe. While profiles in bumper beam and door bars tend to be exposed to force in bending direction, in crash box they are exposed to press force in axil direction. Passive safety members exposed to force in bending direction mainly functions as transfer of the force at the highest level possible and with minimum displacement to both ends (supports). Both ends of bumper beam are connected to crash box. Both ends of door bar are connected to columns A and B. Thus, coming force should be transmitted to crash boxes at minimum displacement and minimum bending deformation and stroke energy from deformation onto crash boxes is expected to be absorbed. On anti-intrusion bar force is carried outside of passenger or driver’s life volume and coming stroke energy is aimed to be met by help of side columns. Due to additional weight caused onto vehicle by all such collision members, vehicle manufacturers try to minimize the thickness of bumper beam, crash box and antiintrusion bar as much as possible for sake of reducing weight of such members. As this weight minimizing process is applied without comprising from expected energy absorption and bending rigidity values it remains at a certain limit and cannot be minimized to the least values.

Figure 1 shows an example of front collision safety members bumper beam and crash box used for cars; Geometry of beam profile has various close cross-sectional applications. Crash box has flat, conical, corrugated and with edge cutting embodiments. Both profiles are used as hollow in general. In various patents and some top segment vehicles metal or polymer basis foam filling samples are seen. Various open or close cross-sectional profiles are used in anti-intrusion bar. While increasing bending strengths at open profiles is relatively difficult, higher weights are achieved in close profiles.

In existing embodiments and studies automotive sector is interested in use of composite materials, for instance, with production of polypropylene matrix composite bumper beam reinforced with carbon and glass fibre, weight is decreased by 33 %, energy absorption increased by 14 % and reduction in occurring displacement is 8 %. Another example is use of aluminium matrix syntactic foam material resulting in more energy absorption at high speeds. In addition, there are also studies based on improvement of compressed bars placed inside collision member and use of expandable foam sticks in parts where the arms meet outer structure. Another example is the studies made for improvement of absorption by giving variable wavy form to collision member. The waves here occur at weak points. In general studies are based on geometric structures and material change of collision member. In the related art it is seen that production of said geometry forms is difficult and studies for minimizing weight are inadequate. During search of the matter, an application numbered EP2809556B1 and entitled “Energy absorbing assembly and methods of making and using the same” was seen. The system discloses use of polymer or metal syntactic foam filling in energy absorption members in vehicles as filler. The system does not disclose an embodiment having lattice and auxetic core structure superiorities and advantages provided by hybrid syntactic foam materials.

Another study encountered during search of the matter is the application numbered DE102020201772A1 and entitled “Crash box fur ein Kraftfahrzeug”. The system relates to crush box collision safety member filled with auxetic core structure. In the system crush box is filled with auxetic core structure not lattice core structure. Therefore, it does not have an advantage that can provide a structure allowing high energy absorption by allowing large deformations inward of the lattice core structure.

Another study encountered during search of the matter is the application numbered WO2020139239A1 and entitled “Impact damping crash box guiding torsion action”. System relates to crush box and added production method comprising lattice structure in various intensity and sizes in various areas and a production method thereof. The solution offered with the system has limited application. It is not appropriate for serial production.

Another study encountered during search of the matter is the application numbered US20160089817A1 and entitled “Method for fabricating a sandwich box impact beam”. System relates to a sandwich structured bumper beam. The primary function expected from bumper beams is to divide into equal values and transmit high bending rigidity and force at minimum deformation onto crush boxes on both sides. The invention protects a bumper beam to help energy absorption deformation.

As a result, due to above-described disadvantages and inadequacy of existing solutions, it has been necessary to make development in the related art.

Aim of the Invention

The invention has been developed with inspiration from existing situation and aims to eliminate the above-mentioned disadvantages.

Polymer and light metal matrix materials that can be produced as meta material (material with designable cross-section geometry) is obtained by adding very low density hollow glass, light metals or ceramic bubbles, contribution of light-weight short fibres of high stregth fibres such as glass, carbon or basalt etc. into the light-weight hybrid syntactic foam materials with required integrity and increased strength were obtained. Thus, collision members used are exposed to plastic deformation and energy thereof is absorbed. Hollow areas inside the collision members (bumper beam and crash box) are used and use of foam materials improves collision members mechanic features.

The invention is achieved as a synthesis of studies taking several years. In a study Yazici (2016) added hollow glass micro ballons into a matrix comprising of rigid polyurethane polymer and silicone mixture and obtained syntactic foam and showed that the strength and energy absorption amount displayed by the foam under high speeds is 9 times higher than polymer of very high resistance very well-known such as Polyurea by SHPB (Split Hopkinson Press Bar) experiments. Ozer et al. (2016) took a further step in the study and showed that used materials developed by Yazici (2106) in bumper beam and crash box as filling material and that when said passive safety members used in vehicles against front impact energy absorption performance is 8 times higher when aluminium profiles are preferred it is 10 times better. This shows that even in case of reduction of vehicle profile weights at said levels, use of filling in vehicle safety will not result in any reduction. Ozer et al. (2107) took one step further and instead of filling inside of crash box entirely, they showed differences of reinforcing in various values and geometries in proportional rates. In conclusion, it is shown that syntactic filling developed by Yazici (2016) improves vehicle safety considerably without causing an increase in weight.

Several studies have been made on three-dimensioned lattice structure sandwich structures and ultra-light weight thermoplastic composite base sandwiches were developed and elasto-plastic behaviours have been suggested by experiments. Thus, it is displayed that high energy absorption capability is provided (Ece Seving, Static and dynamic study of very light sandwich plates of multi-layer pyramid lattice cores of continued continuous fibre reinforced thermoplastic composite base”, BUll, FBE master’s degree Thesis, Advisor: Prof. Dr. Murat YAZICI, 2019).

A doctorate thesis conducted under advisory of Prof. Yazici suggests design of meta materials and suggests different auxetic structured meta foams. Auxetic structures are materials having negative poisson ratio. This means that when an external load affects, expansion in material in vertical directions in line of influence does not exist in contrary material runs inwardly. Experimental studies on such auxetic structured core sandwiches showed that sandwich structures have bending rigidity increasing very much without any increase in weight in respect to conventional sandwiches (Ibrahim Kurgad Turkoglu, “investigation of behaviour of thermoplastic sandwich Structures with auxetic core geometries produced by 3-Dimensional additive manufacturing method under static and Dynamic loads””, BUU FBE PhD Thesis, Advisor: Prof. Dr. Murat YAZICI, 2020).

Primary aim of the invention is to provide a system providing enhancement of performance of vehicle hitting members.

Another aim of the invention is to provide a system providing obtain of a superior featured bumper beam and door bar due to both energy absorption nature and nature of capability to transfer force to supports with less displacement because of increase in bending rigidity because of passive safety members foam structure crashing upon decreasing cross-sectional wall thickness of bumper beam and door bars by means of filling porosity structures of auxetic feature in various geometries into profile spaces independent of beam profile so to increase high bending rigidity expected from bumper beam and door bar at a very high rate.

Another aim of the invention is to create a system providing obtaining auxetic meta foam from fibre reinforced glass or ceramic ballonet additive polymer or metal base syntactic foam.

A further aim of the invention is to design a system providing enhancement of absorption rate with filling by three dimensioned lattice geometry polymer or metal base fibre reinforced syntactic foam structures and reduction in weight due to ultra-light structure of design.

Another aim of the invention is to create a system providing production of light-wight lattice structure from fibre reinforced glass or ceramic ballonet additive polymer or metal base syntactic foam material.

A further aim of the invention is to enable production of three-dimensioned lattice structures or designed auxetic foam structure from hybrid syntactic foams by additive manufacturing technology.

A further aim of the invention is to enable production of three-dimensioned lattice structures or designed auxetic foam structure from hybrid syntactic foams by conventional form giving or additive techniques.

A further aim of the invention is to enable production of three-dimensioned lattice structures or designed auxetic foam structure from hybrid syntactic foams by injection and rotation casting techniques.

A further aim of the invention is to create a system having additional deformation and energy absorption mechanism characterized by each bar member forming lattice structure has syntactic foam feature. Another aim of the invention is to create a system appropriate for serial production because of easy to fill syntactic foam feature lattice structures produced by forming onto one another and thus easily ordering inside crash box.

A further aim of the invention is to provide specifications of passive safety members as listed below.

- Bumper beam: Having high bending rigidity in the beginning, capable to display crashing behaviour at final stage

- Crash box: Crash box capable to display deformation at maximum level and having varying absorption mechanisms for very high energy absorption

- Anti intrusion bar: Side door bar should also be capable to display high bending rigidity like bumper beam. It is expected to transfer hitting force to poles next to door without bending.

To achieve above mentioned aims, the invention is a system providing enhancement of performance of vehicle collision members. Accordingly, the system comprises;

• Crash box enhancing energy absorption nature and having lattice geometry hybrid composite syntactic foam filling,

• Sandwich crash box enhancing energy absorption nature and having lattice geometry hybrid composite syntactic foam multi-layer core,

• Close profile cross section bumper beam enhancing bending rigidity and energy absorption nature, with auxetic geometry hybrid composite foam material filling,

• Open profile cross section bumper beam of sandwich structure enhancing bending rigidity and energy absorption nature, having lattice made from auxetic geometry hybrid composite foam material,

• Anti intrusion bar enhancing bending rigidity and energy absorption nature, with auxetic geometry hybrid composite foam material filling,

• Anti intrusion bar of sandwich structure enhancing bending rigidity and energy absorption nature, having lattice made from auxetic geometry hybrid composite syntactic foam material.

The structural and characteristics features of the invention and all advantages will be understood better in detailed descriptions with the figures given below and with reference to the figures, and therefore, the assessment should be made taking into account the said figures and detailed explanations. Brief Description of the Drawings

Figure 1 shows an example of front collision safety members bumper beam and crash box used for cars,

Figure 2 shows an illustrative view of anti-intrusion bars.

Figure 3A shows view of flat hexagonal honeycomb filling (or core) geometry forming filling structure.

Figure 3B shows a view of re-entrant auxetic filling or (core) geometry.

Figure 3C shows view of re-entrant core sandwich beam of 3-point bending test deformation.

Figure 4A shows a view of double arm auxetic filling or (core) geometry.

Figure 4B shows view of double arm core sandwich beam of 3-point bending test deformation.

Figure 5A shows a view of tetrachiral auxetic filling or (core) geometry.

Figure 5B shows view of tetraciral core sandwich beam of 3-point bending test deformation.

Figure 6 shows illustrative of sandwich structure model having lattice geometry core.

Figure 7A shows view of sandwich material core having two folding placed pyramidal lattice structure.

Figure 7B shows analysis results of structural finite members displaying high deformation capability.

Figure 8 shows sample of sandwich crash box inside filled with lattice geometry core structure formed from bar members in syntactic foam structure.

Figure 9 shows view of sample bumper beam filled with auxetic meta material with syntactic foam feature core.

Figure 10 shows illustrative view of a sample filled with auxetic meta material of syntactic foam filled in open and closed profile cross-section dimensioned anti-intrusion bar.

Figure 1 1 shows illustrative view of a sample filled with auxetic meta material of syntactic foam filled in open profile cross-section bumper beam and close profile cross section anti-intrusion bar.

Description of Part References 1 . Crash box

2. Sandwich crash box

3. Close profile cross-section bumper beam

4. Open profile cross-section bumper beam 5. Close profile cross-section anti-intrusion bar

6. Open profile cross-section dimension side door stroke bar anti-intrusion bar

7. Vehicle body plate

8. Lattice structure filling

9. Crash box body 10. Upper plate

A: A cross-section 20 502. Hollow sphere

B: B cross-section 503. Short fibre reinforcement

C: C cross-section 504. Sandwich back plate

D: D cross-section 801. Unit lattice I: I length 802. Unit lattice matrix

H: H height 25 803. Short fibre

0: 6 angle 804. Hollow micro sphere

501 . Matrix

Detailed Description of the Invention

In this detailed description, the preferred embodiments of the system being subject of the invention have been described only for purpose of better understanding of the matter. Invention is a system providing enhancement of performance of vehicle collision members. Accordingly, the system comprises crash box (1 ) enhancing energy absorption nature and having cage geometry hybrid composite syntactic foam filling, sandwich crash box (2) enhancing energy absorption nature and having cage geometry hybrid composite syntactic foam multi-layer core, close profile bumper beam (3) enhancing bending rigidity and energy absorption nature, with auxetic geometry hybrid composite foam material filling, open profile bumper beam (4) of sandwich structure enhancing bending rigidity and energy absorption nature, having core made from auxetic geometry hybrid composite foam material, side door stroke bar (5) enhancing bending rigidity and energy absorption nature, with auxetic geometry hybrid composite foam material filling, side door stroke bar (6) of sandwich structure enhancing bending rigidity and energy absorption nature, having core made from auxetic geometry hybrid composite syntactic foam material.

Invention is disclosed by use of information and findings obtained from scientific studies. Basic arguments forming scientific basis of invention and obtained because of scientific studies are listed below:

- Auxetic meta structures (having negative poisson ratio) : Have high compression and bending strength and are light-weight because of porosity structure.

- Lattice structures: Have high deformation capability. Thermoplastic composite base lattice structures show high deformation but occurring deformation returns to a level close to initial form after release of load. Cage structures display varying mechanical behaviour during deformation. Main behaviour of them is twisting and plastic deformation behaviour.

- Syntactic foams: Syntactic foams are closed cell, convenient for serial production, are of varying values of density at desired area and high energy absorption capability and particularly has Strain Rate accuracy.

Information from our basic studies is given below.

Syntactic foams closed cells structures produced by additive hollow micro ballons made from materials such as glass, ceramic, plastic etc. selected conveniently according to matrix material (polymer, metal, ceramic). For that reason, they are called as foam. When a load is applied thereon it goes under deformation and it has high energy absorption nature subject to its capability to display energy consumed upon breaking of micro ballons therein and plastic deformation by material forming matrix. They are ultralight materials. For instance, density of syntactic foam of high energy absorption feature developed by Yazici (2016) is 0.252 g/cm3 while pressure resistance is 8.5 MPa. Such values display performance much superior than Polyurea used in several various applications (density 1 g/cm3, Compression strength 5.38 MPa) because of having very high dynamic impact strength. Material integrity is ended under influence of breaking microballons. For that reason, the disclosed invention has high strength short fibre reinforcement such as short carbon, glass, basalt etc. inside syntactic foam. Thus, while material integrity is maintained an essential loss is not encountered in crash behaviour. In this invention, high weight advantage is achieved by means of obtaining high bending rigidity and thus reducing thickness by means of filling close profile cross-section bumper beam (3) profile inside and close profile cross-section anti-intrusion bar (5) inside by auxetic foam structure made from hybrid composite syntactic foam material.

In our invention, high weight advantage is achieved by means of obtaining high bending rigidity and thus reducing thickness by means of production of open profile cross-section bumper beam (4) and open profile cross-section anti-intrusion bar (6) as sandwich structure where use thereof is required and obtaining inside in auxetic foam structure made from hybrid composite syntactic foam material.

Core structure or profile inner filling is honeycomb, corrugate or square structure. Such structures have advantage of production of filling from hybrid composite syntactic material. Our invention also covers such embodiment.

Figure 3A shows details of a unit normal filling cell structure having honeycomb geometry and production from hybrid composite syntactic foam. Figure 3B shows details of one unit cell of re-entrant core structure having auxetic behaviour and production from hybrid composite syntactic foam. Figure 3C shows a sample of permanent deformation after three point bending test of sandwich material having re-entrant core.

Figures 3A, 3B, 3C, 4A, 4B, 5A and 5B show varying auxetic fillings. Inner structure of each filling comprises of hybrid composite syntactic foam material as shown in details in Figure 3A and Figure 5A. With mechanic behavioural advantages of core or filling materials structures produced from hybrid composite syntactic foam material enables novel and superior material and structure by combining capabilities of ultra-light, high deformation features of syntactic foams, high rigidity, easy producible and known current all production techniques in comparison to conventional foams.

Figure 4A and Figure 5A give samples for use of auxetic structures having double arm and tetrachiral square geometry. In case such geometries are profile inside filling or open profile cross-section structure in bumper beams and anti-intrusion bars, they are formed in sandwich structure and in case of forming core, higher rigidity and resistance limits are achieved than current filled or non-filled all bumper beams and side door bars, and in case of exposing to deformation, higher energy absorption is achieved. In addition, production of said core structures from hybrid composite syntactic foam materials provides additional lightness and high energy absorption advantage. The invention is a unique invention by having all such advantages.

Figure 5A shows an illustrative embodiment of auxetic structures of tetrachiral square geometry. Matrix (501 ) is material forming main phase in composite structure. It provides keeping together the additives put therein (fibre, micro ballons etc.) and fulfilment of expected function by composite structure (syntactic foam is also in composite structure). Hollow spheres (502) are added into matrix (501 ) made from polymer, ceramic or metal material and density of material is reduced, and closed cells syntactic foam (composite material) is obtained. It breaks at a certain load value and energy absorption and syntactic foam structure higher deformation is enabled. Short fibre reinforcement (503) is high strength fibres cut in short length. It is used to increase strength-of matrix (501 ). It is desired to be higher from a certain length (critical fibre length) and lower than a certain value. Sandwich lower plate (504) is very light and of increased bending rigidity material obtained by combining very light core material between back and front plates. The surface plate of sandwich material exposed to load is called front plate and plate remaining under core material in loading direction is called back plate.

What expected from crash box (1 ) is deformation of high amount. Here crash box (1 ) inside is filled with filling geometry having varying lattice geometry. Three-dimension lattice geometry is produced from hybrid composite syntactic foam material. Thus, high deformation capability of lattice geometry and hybrid composite syntactic foam is combined, and maximum level collision energy expected from crash box is converted into deformation energy and thus absorption is achieved. As seen in Figure 7A and Figure 7B, when number of layers is increased, deformation amount of lattice core structure increases in proportion. Form where such structures are placed into sandwich crash box (2) is shown in Figure 8. Unit lattice (801 ) is the structure forming a unit cell in three-dimension lattice system and lattice form because of repeating big or small forms. Unit lattice matrix (801 ) is syntactic foam formation made by means of adding hollow micro spheres (804) into unit lattice matrix (802) made from polymer, metal, or ceramic material. More than one reinforcement material can be added to said unit cage matrix (802) subject to place of use. For instance, while hollow micro spheres (804) provide lightness and energy absorption, high strength is achieved when short fibre (803) is reinforced. Figure 8 shows sandwich crash box (2) filled with lattice structure filling (8). Vehicle body plate (7) is the plate where crash box (2) is connected. Sandwich crash box (2) is connected to bumper beam via front plate (10)

In case of any impact the invention helps absorption of current kinetic energy before transmission into inner parts of vehicle. Additionally, allowing designs helping reduction of weight, the current protection function is improved. Maintaining protective function of collision members appropriate for serial production, it helps cost reduction in manufacturing.

References

1 - Yazici, M. (2016) “A Novel High Strain Rate Sensitive Rigid Polyurethane Resin Based Syntactic Foam”, Acta physica polonica A, 129(4), 613-615.

2- Ozer H., Can Y. , Guglu H., Karen I. , Yazici M. (2016) “A Novel High Strain Rate Sensitive Rigid Polyurethane Resin Based Syntactic Foam”, OTEKON 2016.

3- Ozer H., Can Y., Yazici, M. (2017) “Investigation of the Crash Boxes Light Weighting with Syntactic Foams by the Finite Element Analysis”, Acta Physica Polonica A, 132(3), 734-737.

4- Turkoglu i.K. (2020) “Investigation of behaviour of thermoplastic sandwich Structures with auxetic core geometries produced by 3-Dimensional additive manufacturing method under static and Dynamic loads” PhD Thesis, Advisor: Prof. Dr. Murat YAZICI.

5- Seving E. (2019) “Static and dynamic study of very light sandwich plates of multi-layer pyramid cage cores of continued fibre reinforced thermoplastic composite base”, Master Thesis, Advisor: Prof. Dr. Murat YAZICI.

Claims

1. A system providing enhancement of performance of vehicle collision members and characterized by comprising;

• crash box (1 ) enhancing energy absorption nature and having lattice geometry hybrid composite syntactic foam filling,

• sandwich crash box (2) enhancing energy absorption nature and having lattice geometry hybrid composite syntactic foam multi-layer core,

• close profile cross-section bumper beam (3) enhancing bending rigidity and energy absorption nature, with auxetic geometry hybrid composite syntactic foam material filling,

• open profile cross-section bumper beam (4) of sandwich structure enhancing bending rigidity and energy absorption nature, having core made from auxetic geometry hybrid composite syntactic foam material,

• Anti-intrusion bar (5) enhancing bending rigidity and energy absorption nature, with auxetic geometry hybrid composite syntactic foam material filling,

• Anti-intrusion bar (6) of sandwich structure enhancing bending rigidity and energy absorption nature, having core made from auxetic geometry hybrid composite syntactic foam material.

2. The system according to claim 1 and characterized in that, syntactic foam structure forming core structures being of random 3-dimenison reinforced hybrid or plain structure with short fibre.

3. The system according to claim 1 and characterized in that, syntactic foam structure forming core structures having polymer and/or ceramic and/or metal main phase.

4. The system according to claim 1 and characterized in that, auxetic fillings being of tetrachiral square/honeycomb/ corrugate /square structure.

5. The system according to claim 1 and characterized in that said lattice structure being pyramidal.

6. The system according to claim 1 and characterized in that, syntactic foam structure forming lattice structures being matrix of main phase. The system according to claim 1 and characterized by matrix forming main phase of composite structure comprises hollow spheres added thereinto and reducing density of material and providing obtain of closed cells syntactic foam (composite material). The system according to claim 1 and characterized by matrix forming main phase of composite structure comprises fibre reinforcement enhancing strength of matrix.