Thermoplastic Composites for Integrally Woven Pressure Actuated Cellular Structures: Design Approach and Material Investigation

The use of pressure-actuated cellular structures (PACS) is an effective approach for the application of compliant mechanisms. Analogous to the model in nature, the Venus flytrap, they are made of discrete pressure-activated rows and can be deformed with high stiffness at a high deformation rate. In previous work, a new innovative approach in their integral textile-based manufacturing has been demonstrated based on the weaving technique. In this work, the theoretical and experimental work on the further development of PACS from simple single-row to double-row PACS with antagonistic deformation capability is presented. Supported by experimental investigations, the necessary adaptations in the design of the textile preform and the polymer composite design are presented and concretized. Based on the results of pre-simulations of the deformation capacity of the new PACS, their performance was evaluated, the results of which are presented.

Microstructural Evaluation of a 5052 H34 Aluminum Alloy Used in Multilayered Armor

Among the aluminum alloys, the 5052 has been extensively investigated aiming at high rate deformation applications, owing to its high mechanical strength, plasticity and toughness. In this work, the microstructure and microhardness of a 5052 H34 alloy were investigated. This alloy was subjected to ballistic impact with 7.62 mm ammunition as back layer of a multilayered armor system composed of a ceramic and a composite material. An increase in the microhardness was observed. However, changes in the microstructure were not significant. The fracture aspect of the alloy in the high deformation rate was compared to that of a tensile tested sample. A stronger plastic behavior was verified in ballistic tested samples.

Electromagnetic Embossing of Optical Microstructures

Electromagnetic forming (EMF) is a high-speed forming process that is already established in the macroworld. Due to its advantages like high deformation rate and cheaper tools, it is introduced to microforming. In this research, the replication of prismatic optical microstructures is investigated. EN AW-1050A (Al99.5) micrometal sheets with a thickness of 50 μm and 300 μm are electromagnetically micro-embossed. With this technique, it is possible to successfully replicate triangular cross section micro V-grooves of 86.6 μm in width and 24.1 μm in depth with an average surface roughness of Sa = 44 nm. The microstructures of the embossing tool are generated by diamond micro chiseling (DMC), a novel machining process to produce microstructures with discontinuous geometry, like miniature cube corner retro reflectors and V-grooves with well-defined endings.

Effect of Hot Deformation Temperature on Texture Formation Regularity of CGO Silicon Steel under High Deformation Rate

The influence of hot deformation temperature on microstructure and texture of CGO silicon steel under the condition of a high deformation rate (100 s-1) was studied by SEM and EBSD techniques. The results indicate that the typical microstructures at room temperature consist of ferrite and pearlite under different hot deformation temperatures. The higher deformation temperature is beneficial to obtain a more uniform recrystallization microstructure and lower pearlite content. Cubic texture{100}001and rotated cubic texture{100}011are dominant texture components in the tested steels, and{111}112texture inγfiber is also strong, the intensity of which is higher than that of{111}110texture. Goss texture{110}001is weak. With the rising of the hot deformation temperature,{100}011texture decreases firstly and then increases at 1100°C. When the hot deformation temperature raises from 800°C to 900°C,{111}112texture shows an increasing trend, while{111}110texture content is stable. When the temperature further increases to 1100°C and 1150°C,{111}112and{111}110textures are slightly weakened.

Texture Formation of α2-Ti3Al during Hot Forming of γ-TiAl Based Alloys

ABSTRACTIn the present study the α2 and the γ texture in a Ti-45Al (at.%) alloy were analyzed by means of x-ray diffraction after hot deformation. The initial Ti-45Al powder compact exhibits a random texture and shows a relatively high amount of α2 phase (about 34 vol.%). Various hot compression tests were performed at temperatures ranging from 700 °C to 1100 °C with strain rates of 5·10–4 s–1 and 5·10–2 s–1 up to a true deformation of ε = –1.Depending on the deformation temperature the γ-TiAl deformation texture consists of pure deformation components (700 °C) or components completely related to dynamic recrystallization (1100 °C). In contrast to the γ phase the α2 phase shows no remarkable changing of the deformation texture with increasing temperature. The α2 deformation texture basically consists of a similar component as it is known from hexagonal α-Ti, namely a tilted basal fiber. However, a significant influence of the deformation rate on the α2 texture formation is observed at temperatures above 800 °C. With increasing deformation temperature the α2 texture strengthens by applying a high deformation rate, whereas it weakens for a low deformation rate. This contrary behavior is attributed to the interaction of the α2 and γ phases during texture formation.