1,721,243 research outputs found
Adaptive, Tolerant and Efficient Composite Structures - Introduction
No full textPolymer composites offer the possibility for functional integration since the material is produced simultaneously with the product. The efficiency of composite structures raises through functional integration. The specific production processes of composites offer the possibility to improve and to integrate more functions thus making the structure more valuable. Passive functions can be improved by combination of different materials from nano to macro scale, i.e. strength, toughness, bearing strength, compression after impact properties or production tolerances.
Active functions can be realized by smart materials, i.e. morphing, active vibration control, active structure acoustic control or structure health monitoring.
The basis is a comprehensive understanding of materials, simulation, design methods, production technologies and adaptronics. These disciplines together deliver advanced lightweight solutions for applications ranging from mechanical engineering to vehicles, airframe and space structures along the complete process chain.
The book provides basics as well as inspiring ideas for engineers working in the field of adaptive, tolerant and robust composite structures
Nanoscaled Boehmites Modes of Action in a Polymer and its Carbon Fiber Reinforced Plastincs
No full textSurface Quality of Carbon Fibre Reinforced Nanocomposites: Investigation and Evaluation of Processing Parameters Controlling the Fibre Print-Through Effect
No full textThe chapter investigates the effect of the essential manufacturing parameters on the surface quality of uncoated carbon fibre reinforced composites (CFRP) used as car body panels with visible surfaces (Class A properties). A series of CFRP laminates maunfactured by the RTM technique are investigated varying in the fibre volume content (30–60%), reinforcement material (woven fabrics vs. unidirectional fibre reinforcements), curing temperatures (40–120 °C), additives (SiO2-nanoparticles as matrix fillers) and using a surface finish applied as an in-mould coating. The laminate surfaces are characterized by roughness analysis (white-light interferometry) and wave-scan measurement to quantify the influence of the different manufacturing parameters on the surface quality. Especially the used resins are intensively characterized concerning thermal properties (CTE) and total resin shrinkage. These results correlate very well with the performed analysis of surface roughness. It is found that the fibre print through effect is significantly reduced by realising low total resin shrinkage and an even distribution of resin and fibres at the surface. Thus, using of unidirectional fibre reinforcement (no weft or sewing threads; very fine filaments), low curing temperatures (slow curing processes) and an in-mould coating are most successful for reduction of fibre print through effect and getting surface similar to Class A properties. In addition, the surface quality is quite positively affected by the application of nanoparticles and also strongly controlled by roughness of tooling
Fundamental characterization of epoxy-silica nanocomposites used for the manufacturing of fiber reinforced composites”
No full textNanocomposites based on silica nanoparticles and high performance epoxy resins are investigated for their suitability as a new type of matrix for fibre-reinforced polymers (FRP) using injection technologies (LCM). The key focus is on the determination of the pro-cessing parameters at varying silica nanoparticle content. The homogeneous distribution of the nanoscaled silica in the epoxy matrix is proven by Photon Cross Correlation Spectroscopy (PCCS) and Scanning Electron Microscopy (SEM) analysis. Depending on the silica content of the composite, its stiffness, strength and toughness can be increased significantly compared with the neat resin. The mechanical performance is discussed by failure mechanisms based on the analysis of the fracture surface morphology. Moreover, resin shrinkage and the thermal expansion are significantly reduced both important for lowering internal stress in FRP. The injectability of the nanocomposite for the purpose of lamination using the LCM technology is nearly unaffected. Epoxy-silica nanocomposites are now proven to be a new high performance polymer matrix for FRP structures manu-factured by the low cost LCM technique
Nanoscaled Boehmites' Modes of Action in a Polymer and Its Carbon Fiber Reinforced Plastic
No full textAdvanced Flame Protection of CFRP Through Nanotechnology
No full textThis chapter refers about the optimization of fire resistance of CFRP. For this optimization the most promising nano scaled additives are used and varied regarding the particle content, size and effect of flame retardancy. One major challenge
is to optimize the particle dispersion and to determine the optimal particle concentrations in consideration of the effect of flame retardancy and the resulting material properties. Additionally a fire testing method has to be determined that resolves the potentially small differences in the used variations. Therefore standard fire and mechanical test's are used as well as a simple thermal material method, given with the thermo gravimetric analysis (TGA) including a single differential thermal analysis (SDTA) that also suits for a fast comparison of the materials fire properties. Hereby obtained results are compared and a related behaviour of the fire properties can be shown between tandard fire te ts and thermal material tests using the TGA-device
Boom Concept for Gossamer Deployable Space Structures
No full textDeployable structures are necessary to realize large but weight-efficient space systems. DLR provides a deployable mast that can be used either at once to realize e.g. long dipole antennas of some ten meters or to setup structures that use this mast as basic building block structure. This section shall, therefore, enable a basic insight on the concept and of the resulting challenges. Moreover, a deploy-ment test series under weightlessness is presented and evaluated to show possible concepts of deployment control and demonstrate the potentials
- …
