[en] Environmental concerns are increasing within the industy, especially in the automotive industry. On one hand, they are making efforts to reduce the CO2 emissions and on the other hand, they are working in the development of the electric vehicles which do not produce emissions. In order to reduce emissions, the fuel consumption of the engines must be reduced and one of the strategies that they are following is focused in lightweighting. Regarding the electric vehicles, one of the limitations that they have is the range limitations, which partly are due to the high weight of the battery pack. Therefore, lightweight strategy is something that is in mind of the OEMs of actual vehicles and electric vehicles. However, safety of the passengers must be ensured in spite of reducing the overall weight of the vehicle. For this reason, over the last decades, there is a huge research about lightweight materials with higher mechanical properties. Composite materials are some of them. The actual impact structures are made of metallic materials such as steel and aluminium. In the present thesis, impact structures made of composite materials are analysed and developed in order to reduce the weight of the component and increase the energy absorption capabilities in a crash scenario. The influence of the reinforcement type and the laminate stacking secuence in energy absorption capabilities of the material is analysed. Unidirectonal and bidirectional E-glass fibres and bidirectional basalt fibres are used in order to maximize the absorbed energy and determine which the best reinforcement material for this application is. Another parameter that have been analysed in the present investigation is the effect of the fibre volume fraction in energy absorption capability. It has been found that there is an optimum fibre content value which maximizes the energy absorption of the structure during the crushing process. Most of the research has been focused in analysing the influences of the different parameters in the crushing stage of a unitary semi-hexagonal profile. However, combination of semi-hexagonal profiles as honeycomb concept, allows designing and manufacturing different impact structures optimized for each type of vehicle, depending the characteristics and energy to be absorbed in each case. For this reason, the effect of the geometry due to the combination of the semi-hexagonal profiles has been also analysed. The results have shown that increasing the corrugation level of the structure, the specific energy absorption capability of the structure is higher. The experimental development of automotive components is expensive. Therefore, using an accurate numerical model that is capable to predict the behaviour of a composite structure during crushing process, experimental costs can be overcome. In consequence, a numerical model that is capable to predict accurately the crushing behavior of a composite structure has been developed. Once the numerical model has been validated with experimental results, a numerical optimization of the semi-hexagonal geometry has been made by finite element analysis. One of the limitations of the composite materials is the lack of productivity due to the manufacturing processes. In this line, the crush properties of the material manufactured by a new process which is under development by Mondragon Unibertsitatea have been characterized. The new manufacturing process is based on the traditional pultrusion process but with alternative UV curing system. The curing of the material is done out of the mould and this allows manufacturing the material in a continuous and automatized way, with higher productivity than the traditional pultrusion process. The crushing properties of the material manufactured by UV pultrusion have been compared with the properties of the material manufactured by vacuum assisted infusion process and hand lay-up process. The results have shown that the materal properties of UV pultrusion are similar or even higher than the properties of the same material manufactured by other processes. Finally, real composite impact structures manufactured by UV pultrusion process have been integrated in an electric light truck vehicle prototype in order to test them in a real crash test scenario. The results have validated the high energy absorption capabilities of the composite structures in a crash scene. The absorbed specific energy quantities have been significantly higher comparing with the metallic impact structures.

[eu] Ingurugiroarekiko ardura geroz eta handiagoa da industriako hainbat sektoretan, bereziki automobilgintzan. Alde batetik CO2 emisioak murriztea dute helburu eta bestetik, auto elektrikoen garapenean dabiltz burubelarri lanean. CO2 emisioak murrizteko motorren kontsumoa gutxitu beharra dago eta hori lortzeko estrategietako bat autoen pisua murriztean datza. Auto elektrikoei dagokienez, eragozpen handienetako bat hauek duten autonomia mugatua da, hein handi batean bateriek duten pisu altuaren eraginez. Hori dela eta, autoen pisua murriztearen estrategia gaur egungo autoak eta auto elektrikoak garatzen dituzten fabrikatzaileen agendetan txertatuta dago. Aitzitik, autoen pisu murrizketak ezin du inolako eraginik izan bidaiarien segurtasunean. Arrazoi hori medio, azken hamarkadetan ikerketa ugari ari dira egiten propietate hobeak dituzten material arinen inguruan, autoaren pisua murrizteaz gain bidaiarien segurtasuna hobetzeko asmoz. Material hauen artean aurkitzen dira matrize polimerodun material konposatuak eta hain zuzen ere, ikerketa hau mota honetako materialetan oinarritzen da. Gaur egungo autoetako inpaktu egitura gehienak altzairua edo aluminioa bezalako material metalikoz eginda daude. Tesi honetan berriz, material konposatuz eginiko inpaktu egiturak aztertzen eta garatzen dira. Modu honetan osagai hauen pisua murrizteaz gain, auto istripu batean sortzen diren energia kantitate handiagoak xurgatzeko ahalmena lortzen da. Alde batetik zuntz mota ezberdinek eta zuntz hauen sekuentziak, egituraren energia espezifikoa xurgatzeko ahalmenean duen eragina aztertzen da. Horretarako, norabide bakarrean eta bi norabidetan zuzendutako beira zuntzak eta bi norabidetan zuzendutako basalto zuntzak erabiltzen dira, zuntz material egokiena aukeratu eta egituraren energia xurgatzeko ahalmena hobetzeko asmoz. Lan honetan azterturiko beste faktore bat, zuntz portzentaiak egituraren kolapso portaeran duen eragina da. Emaitzak aztertuz, egituraren energia xurgatzeko ahalmena maximizatzen duen zuntz portzentaia jakin bat dagoela ondorioztatu da. Ikerketaren zati handi bat, hainbat propietatu aldatuz egitura semi-hexagonal unitario batek kolapsorako duen portaera aztertzean oinarritu da. Hala ere, perfil semi-hexagonal hauek abaraska kontzeptuan oinarrituta konbinatuz auto ezberdinentzako baliagarriak izan daitezkeen egitura modularrak garatu ahal izatea da ideia Laburpena vi nagusietako bat. Hori dela eta, perfil hauek konbinatuta lortzen diren geometria ezberdinek energia xurgatzeko ahalmenean duten eragina aztertu da. Egituren ondulatze maila handitzen doan heinean egituraren xurgamen ahalmena handiagoa dela ikusi da. Entsegu experimentalek duten kostu ekonomiko altua dela eta, gaur egun automozioko osagai gehienen garapen ia guztia simulazio numeriko bidez burutzen da. Arrazoi hori medio, egiturak entsegu experimentaletan kolapsoan erakutsi duen portaera zehaztasunez aurreikustea ahalbideratzen duen herraminta numeriko bat garatu da. Behin entsegu experimentaletako emaitzak numerikoki balidatu ostean, perfil semi-hexagonalaren sekzioaren optimizazio bat egin da simulazio numeriko bidez, energia xurgapen ahalmen handiena duen geometria aurkitzeko asmoz. Material konposatuen muga handienetako bat, gaur egungo fabrikazio prozesuen produktibitate falta da. Muga hau gainditzeko asmoz, Mondragon Unibertsitateak garapen fasean daukan prozesu berri baten bidez fabrikatutako materialaren kolapso propietateak aztertu dira. Prozesu berri hau, pultrusio prozesu tradizionalean oinarriturik dago. Aitzitik, materialaren ontze prozesua moldetik kanpo ematen da eta ontze sistema termikoa izan beharrean, izpi ultramore (UV) bidezkoa da. Modu honetan, material konposatuzko perfilak modu automatizatu, jarrai eta automozio industriak behar duen kadentzietan fabrikatzeko gai da prozesu hau. UV bidezko pultrusio prozesuarekin fabrikatutako materialaren propietateak, huts-poltsaz lagunduriko infusio prozesuarekin eta esku-kontaktu bidezko prozesu tradizionalarekin fabrikatutako materialen propietateekin alderatu dira. Lortutako emaitzen arabera, prozesu berriarekin fabrikatutako materialaren propietateak maila berean edota maila altuagoan daudela ikusia. Azkenik, auto elektriko baten prototipo batean, UV pultrusioz fabrikatutako inpaktu egitura erreal batzuk integratu dira kondizio errealak simulatuko dituen istripu entsegu experimental bat burutzeko. Emaitzen arabera, material hau aplikazio hauetarako baliagarria dela egiaztatu da. Istripu entseguan xurgatutako energia kantitateak, material metalikoz