Unintentional drop of munitions could be encountered during the storage, transportation, and loading processes. In such an impact, malfunctioning of crucial components of munitions is the worst scenario that may be encountered and level of loads should not reach to critical levels. From two possible methods, experimental one is not frequently applied owing to high cost of money and time. On the contrary, particularly in last couple of years, interest is shifted to numerical simulations such as finite element method. In this thesis, foam materials will be investigated as energy absorbers to reduce the effect of loads during the impact. However, modeling the behavior of foam materials by FE codes is a challenging task. In other words, more than a few material parameters which are not commonly specified in literature are sufficient to represent the behavior of foams in an appropriate way. For this reason, material characteristics of the selected two foam materials, expanded polypropylene and v polyethylene, have been obtained in this study. Characterization of EPP and PE is followed by the selection of the appropriate material models in LS-DYNA which is a nonlinear explicit finite element code. Drop tests of munitions on which initially specified foam materials are integrated were done to identify the load levels. Validation of drop tests which are explained in detail in this thesis has been accomplished by LS-DYNA. Final section of the thesis is related to optimization of the foam geometry which will provide reducing load levels to allowable limits. After optimization studies, three alternative geometries which succeed in to reduce loads to allowable load levels were reached. Finally, one of three alternatives is selected considering cost and manufacturing difficulties.

Arbetet syftar till att ta fram en hållbar infästning för virveldämpare till SSRS drönare av modell flygande vinge. Drönaren är specifikt framtagen för att användas till maritima sök och räddningsuppdrag och för att bidra till att utöka den svenska kustens säkerhet. Arbetet studerar ett landningsscenario för drönaren och utifrån detta tas en ny infästning fram. Infästningen av virveldämparen skall vara lätt att hantera för personalen, kräva minimalt med reparation och hålla för 50 landningar. Infästningen skall kunna utlösa och separera virveldämparen från vingen om det under landningen uppstår så stora krafter att dessa komponenter riskerar att ta skada. Arbetet följer DRM-struktur och syftar till att ta fram en prototyp med hjälp av en uttömmande idégenerering utförd med metoderna Speedstorming, Brainstorming och SCAMPER. Konceptsållningen sker med hjälp av anpassade poängsättningsmetoder och Pugh-analys. Det resulterande konceptet bestämmer vilka dimensioner som krävs för att kunna utföra hållfasthetsberäkningar på den valda infästningen, därefter skapas en prototyp vilken används för att utföra hållfasthetstester. De utförda beräkningarna och testerna gav olika resultat och den därav dragna slutsatsen medförde att materialegenskaper rörande elastisk deformation och variabler på hållfasthetstestet ej har beaktas. Testerna visade att den framtagna prototypen av expanderad polypropen hanterade de förutsedda krafterna väl även om testerna inte kunde utföras under helt verklighetstrogna landningsförhållanden. Slutresultatet av projektarbetet är att den framtagna infästningen av virveldämparen har, utifrån tillgängliga testningsmetoder, påvisat önskade egenskaper och att utförligare tester behöver genomföras för att avgöra om den uppfyller samtliga produktkrav. / This work is aimed at producing durable attachments for winglets on a drone, model flying wing, owned by the SSRS. The drone is specifically developed to be used for maritime search and rescue missions and to contribute to increasing the security along the Swedish coast and major inland lakes. During this work only one landing scenario by the drone was studied while creating the attachments, which required to be easy to handle, minimal to no repair work and a durability for 50 landings. The attachments also need to be able to release in case of excessive force during landing which risks jeopardizing the integrity of the wing or winglet. The work followed the DRM-structure and aimed to create a prototype through an exhaustive idea generation technique in three steps using the methods Speedstorming, Brainstorming and SCAMPER. All of these methods go through voting, Pugh analysis and concept screening. After one concept had been singled out its dimensions were decided on and used in calculations to determine its strength. From this information a physical winglet attachment prototype made of expanded polypropylene was created and used in strength and durability tests. Calculations and tests were found to have varying results and the conclusion was made that the material properties regarding elastic deformation and test variables most likely had not fully been taken into account. The tests failed to generate a realistic landing scenario given the requirements but still gave a positive result concerning the prototype's ability to absorb shock loads at landing. This work has resulted in a preliminary winglet attachment prototype which through testing has shown satisfying shock absorbing abilities, and that further testing is required to decide whether the attachment can meet all of the set product requirements.