Joining of Dissimilar Materials for Lightweight Construction in Automotive, Aerospace and Shipbuilding
Lightweight constructions are currently of high interest for several industrial applications, like automotive, shipbuilding and aerospace, in order to meet the environmental requirements according to the reduction of the CO2-emissions. This demand can be met by replacing heavier material with lighter ones. One of the resulting relevant dissimilar material combinations is made of steel and aluminum alloys. However, the welding of these material combinations is characterized by a poor weldability, due to different physical properties and the formation of hard and brittle intermetallic phases, which may lead to cracks. The laser welding may be more suitable compared to other fusion welding process, due to its specifically advantages regarding high welding speed, low distortion and the controlled melting of the both different materials. In addition, owing to prominent strength and stiffness properties, continuous glass and carbon fiber reinforced composite structures are recognized as having a significant lightweight construction potential for a wide variety of applications. The use of composites based on thermoplastic matrix materials is a growing trend in particular in the aerospace sector. Significant advantages of this material class compared to thermoset systems are nearly unlimited storage times of semifinished products, flame retardant properties, higher impact tolerances and mainly the weldability. In this context, laser welding of thermoplastic composite parts becomes increasingly important as a controllable and reliable joining technique. A novel generation of thermoplastic stiffening panels has been developed, consisting of hybrid composite structures, which are based on a carbon fiber reinforced supporting structure and a glass fiber reinforced face sheet. Application examples and further potential of these laser technologies for lightweight construction will be presented.
The Latest Actions of Technology Research Association for Future Additive Manufacturing (TRAFAM)
Technology Research Association for Future Additive Manufacturing (TRAFAM) was carried out the following two projects(A) and (B) in order to develop the innovative Additive Manufacturing systems that would meet the world’s highest standards and the manufacturing technologies for high-value-added products. The results obtained in FY2017 are as follows:
(A) Next-generation industrial 3D printers project
(1) TRAFAM is currently developing Powder Bed Fusion and Direct Energy Deposition types of metal AM machines with electron or laser beams. The EB-PBF machine with an electron gun and electron optic system for 6kW was developed by JOEL, and also the large-scale (Build size: 500 x 500 mm) EB-PBF machine were developed by Tada Electric.
(2) The LB-DED machine with high performance nozzle was developed by Toshiba, and also the hybrid-type LB-DED machine with a monitoring and feedback system was developed by MHI.
(3) The large-scale (build size: 600×600) LB-PBF machine was developed by Matsuura.
(4) The multi-physics model in the PBF system was constructed to simulate the melting and solidification phenomena at a microscopic level by using a super computer.
(5) The thermal elastic-plastic simulation program was developed by using the inherent strain method in order to predict the deformation of the parts fabricated by directed energy deposition (DED). The results analyzed by the inherent strain method coincided considerably with those of the thermal elastic-plastic FEM analysis by optimization of the inherent strain of materials.
(B) Development of 3D printing systems for sandcasting cores and molds
The first and large AM machine with the organic binder and coated sand was developed by FY2016, and then the desired value of build speed (100,000 cc/h) and work size (more than 1000×1000 x600 mm) was achieved. In FY2017, the large-scale machine (work size: 1800x1000x750 mm) was developed.
Integration of the “nano-function” into products is still limited due to drawbacks of gas phase and chemical synthesis methods regarding particle aggregation and contamination by adsorbates causing deactivation of the building blocks´ surface. In addition, thermodynamically-controlled synthesis methods naturally facelimited access to alloy nanoparticle systems with miscibility gaps.
As an alternative synthesis route, nanoparticle generation by pulsed laser ablation in liquids has proven its capability to generate ligand-free colloidal nanoparticles with high purity for a variety of materials.1,2 Good reproducibility and significant up-scaling of nanoparticle generation wereachieved recently by a continuous flow synthesis using a high-power ultrafast laser system leading to productivities of up to 4 g/h colloidal nanoparticles.3The transferability of this synthesis route to a variety of materials and liquids further enabled high-throughput screening of molar fraction series of e.g. water oxidation catalysts.4Alloynanoparticles series (i.e., AgAu, NiMo, AuFe, AgNi, FeNi) were synthesized and their phasestructure as well as their application potential will be discussed. Interestingly, on the one hand, phasediagram seems to play a role in ruling the nanoparticles crystal structure and phasesegregation, but at the same time,unusualstructures difficult to access by conventional synthesis methods are yielded,indicating kinetic control.5
In this talk, laser synthesis of colloidswill be introduced at the example of metal and alloy nanoparticles, including the resulting material properties. Application of these laser-generated nanoparticles by supporting them on carrier structures for heterogeneous catalysis2, or in biomedicine6will be demonstrated.
5 years of CIM-Laser: industrial impact, UK strategy development and new research directions
The EPSRC Centre for Innovative Manufacturing in Laser-based Production Processes (CIM-Laser), a collaboration between Heriot-Watt, Cranfield, Cambridge, Manchester and Liverpool Universities was funded in 2012 with a £5.6M grant from EPSRC for a period of 5 years. In this timeframe CIM-Laser has funded 47 projects and engaged with >20 industrial partners. Our research has spanned many different industrial sectors (from aerospace to medical) and scales (from microns to metres). In addition to our research portfolio, we worked closely with the Association of Industrial Laser Users and a wide range of stakeholders to develop Lasers for Productivity – a UK Strategy,which was launched in 2018 at the Houses of Parliament.
In this presentation I will focus on some of the key impacts arising from the Centre’s research, including, for example, directly written holograms for anti-counterfeiting (now being commercialised by Sisma); the development of a 4-laser system for additive manufacturing (commercialised by Renishaw in their Quad laser AM machine); and Wire + Laser Additive Manufacture, now being developed as part of the EPSRC wire-based AM Programme Grant, NEWAM.