Journal of KONES Internal Combustion Engines 2003, vol. 10, 3-4 ANALYSIS OF DEFORMATION IN COMPOSITE PISTONS OF A DIESEL ENGINE Andrzej Niewczas, Cezary Sarnowski Department of Internal Combustion Engines, Lublin University of Technology Poland, Nadbystrzycka 36 Str., 20-618 Lublin, tel. (+48 81)5381258 e-mail: cezar@archimedes.pol.lublin.pl; niewczas@archimedes.pol.lublin.pl Abstract The paper presents some results of simulational research of composite pistons used in a direct injection diesel engine. Pistons were locally reinforced with Al 2 O 3 in the area of piston crown. An optimization attempt applied to piston shape and dimensions of preforms sealed in pistons is also presented, in respect of existing thermal loads and respective temperature distribution as well as distribution of stress and strain with regard to direction of de- formation relatively to global coordinate system. ANALIZA ODKSZTAŁCEŃ TŁOKÓW KOMPOZYTOWYCH DO SILNIKA O ZAPŁONIE SAMOCZYNNYM Streszczenie. W referacie przedstawiono wyniki badań symulacyjnych tłoków kompozytowych do silnika o zapłonie samo- czynnym z wtryskiem bezpośrednim, zbrojonych lokalnie Al 2 O 3 w obrębie korony. Przedstawiono również próbę optymalizacji kształtu tłoka i wymiarów preform zatapianych w tłokach ze względu na występujące obciążenia cieplne i odpowiadające im pola temperatur oraz rozkłady naprężeń i odkształceń, z uwzględnieniem ukierunkowa- nia odkształceń w stosunku do osi globalnego układu współrzędnych. 1. Introduction Pistons are among most mechanical and thermal loaded components of internal combus- tion engines. They have to meet very high demands regarding dimensional stability, strength and durability. It is hard to meet these requirements using classical materials and technolo- gies. Nowadays, the most often used are aluminum alloys founded in metal moulds with cast iron or steel inserts [4]. One of solutions providing required functional parameters of the pistons can be application of composite materials. Composites, comparing to presently used materials, have very advan- tageous features, like lower coefficient of thermal expansion and higher values of strength parameters [1, 5]. The paper presents some results of simulational research of pistons locally reinforced with composite AK12+Al 2 O 3 in the area of piston crown. The aim of research was to analyze the influence of local reinforcement of piston crown on thermal deformations and determine suit- able constructional proportions of preforms used in production of composite pistons for direct injection diesel engine, operated under severe conditions. 2. Research object and method of investigation Research was done using numerical models of pistons used in a DI diesel engine. Models were prepared on the basis of piston with 90 mm diameter for one cylinder test engine. Evaluation was done using serial production piston as a reference and modified pistons. Modification of the piston construction consisted in local introduction of composite material