The effect of the welding parameters and the coupling agent on the welding of composites

Abstract

This paper presents an experimental investigation of the welding of a glass-fiber-reinforced PP composite. The goals of this paper are to investigate the issues of local changes of the welding strength that depend on the heating time and the coupling agent (MAPP). Composite samples were prepared by using an extruding (for mixing) process and a hot-press method. The PP matrix was reinforced by unidirectional short glass fibers. The welding process for the specimens was carried out using a non-contact heated tool butt welding process. Tensile and fatigue tests were conducted to investigate the effects of the heating time parameter and the coupling agent. The highest weld strength dependent on the heating time was achieved with 94 % relative to the base strength of the material. The fatigue behavior of short-fiber-reinforced thermoplastic composites (polypropylene/20 % of volume fractions of E-glass fiber) is presented in terms of stress versus the number of cycles to failure. The specimens were fatigue tested at various percentages of their static tensile strengths at a load ratio R = 0.1 and frequency f= 5 Hz. An indefinite fatigue life was obtained at 35 % of the static damage initiation load for glass-fiber-reinforced specimens. Then, these specimen's maximum welding strengths and fatigue properties that were dependent on the heating time were compared. Keywords: plastic material, composite, heated tool, welding process, reinforcement, fatigue, polypropylenê lanek predstavlja preiskavo varjenja PP kompozita, oja~anega s steklenimi vlakni. Cilj~lanka je bil preiskati vpliv lokalnih sprememb na trdnost zvara, ki je odvisna od~asa ogrevanja in sredstva za spajanje (MAPP). Kompozitni vzorci so bili pripravljeni z uporabo metode ekstruzije in vro~ega stiskanja. PP osnova je bila oja~ana z usmerjenimi kratkimi steklenimi vlakni. Postopek~elnega varjenja vzorcev je bil izveden z brezkontaktno ogrevanim orodjem. Izvedeni so bili natezni preizkusi in preizkusi utrujenosti, da bi ugotovili vpliv~asa ogrevanja in sredstva za spajanje. Najve~ja trdnost zvara v odvisnosti od~asa ogrevanja je bila 94 % trdnosti osnovnega materiala. Obna{anje pri utrujanju termoplasti~nega kompozita (polipropilen/20 % prostorninskih dele`ev E-steklenih vlaken), oja~anega s kratkimi vlakni, je prikazano na krivulji utrujanja kot odvisnost napetosti od {tevila ciklov. Utrujenost vzorcev je bila preizku{ana pri razli~nih odstotkih stati~ne natezne trdnosti, pri hitrosti obremenjevanja R = 0,1 in frekvenci f = 5 Hz. Zdr`ljivost na utrujanje s steklenimi vlakni oja~anih vzorcev je bila dobljena pri 35 % nazivne stati~ne obremenitve. Primerjane so bile maksimalne trdnosti zvarov, z obna{anjem pri utrujanju v odvisnosti od asa ogrevanja.