Research Article Sandwich Structured Composites for Aeronautics: Methods of Manufacturing Affecting Some Mechanical Properties Aneta Krzyhak, 1 MichaB Mazur, 2 Mateusz Gajewski, 2 Kazimierz Drozd, 2 Andrzej Komorek, 1 and PaweB PrzybyBek 1 1 Aeronautics Faculty, Polish Air Force Academy, Ulica Dywizjonu 303, No. 35, 08-521 Dęblin, Poland 2 Mechanical Engineering Faculty, Lublin University of Technology, Ulica Nadbystrzycka 36, 20-618 Lublin, Poland Correspondence should be addressed to Aneta Krzy˙ zak; a.krzyzak@wsosp.pl Received 9 February 2016; Revised 10 May 2016; Accepted 16 May 2016 Academic Editor: Linda L. Vahala Copyright © 2016 Aneta Krzy˙ zak et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Sandwich panels are composites which consist of two thin laminate outer skins and lightweight (e.g., honeycomb) thick core structure. Owing to the core structure, such composites are distinguished by stifness. Despite the thickness of the core, sandwich composites are light and have a relatively high lexural strength. hese composites have a spatial structure, which afects good thermal insulator properties. Sandwich panels are used in aeronautics, road vehicles, ships, and civil engineering. he mechanical properties of these composites are directly dependent on the properties of sandwich components and method of manufacturing. he paper presents some aspects of technology and its inluence on mechanical properties of sandwich structure polymer composites. he sandwiches described in the paper were made by three diferent methods: hand lay-up, press method, and autoclave use. he samples of sandwiches were tested for failure caused by impact load. Sandwiches prepared in the same way were used for structural analysis of adhesive layer between panels and core. he results of research showed that the method of manufacturing, more precisely the pressure while forming sandwich panels, inluences some mechanical properties of sandwich structured polymer composites such as lexural strength, impact strength, and compressive strength. 1. Introduction In the case of modern engineering materials included in aeronautical materials, apart from strength properties, low weight of the inal element is a crucial aspect. Such properties are directly connected with increasing operational properties of a given structure [1–3]. he most common purpose of man- ufacturing sandwich structures [4] is to obtain the greatest stifness at minimum total density (average). All the men- tioned parameters can have satisfactory values provided that the following conditions are met: produced structures will be distinguished by low quantity (density) of faults and lower amount of resin in the material. Improving these conditions of production is the scientiic objective of developing more efective and advanced manufacturing methods. he continu- ity of the sandwich structure is especially signiicant in aero- nautics, where a structural fault may lead to the failure of a ly- ing object in consequence of subsequently happening events. Values of distinctive parameters of an engineering mate- rial inluence possibilities of its later use. A proper knowledge of the material’s characteristics allows for producing an ele- ment of desirable properties with using speciied resources, in relation to the applied technology and the purpose of use in a speciic work environment. he essential characteristics of a structural material are its physical and mechanical properties. he knowledge of these characteristics allows for estimating the material’s reaction to mechanical loads, which occur during its later use in a speciic environment. Additionally, a proper durability of use is ensured [5–8]. Sandwich structures are light materials which show considerable stifness and high ratio of strength in relation to weight. he main concept of the sandwich panel is that exterior surfaces transfer loads caused by bending (lexural load and compression), while the core transfers load caused by shearing. Accordingly, the work mode of the sandwich Hindawi Publishing Corporation International Journal of Aerospace Engineering Volume 2016, Article ID 7816912, 10 pages http://dx.doi.org/10.1155/2016/7816912