Lightweight Design Concepts Research Articles

Multidisciplinary design optimization of large wind turbines—Technical, economic, and design challenges

Wind energy has experienced a continuous cost reduction in the last decades. A popular cost reduction technique is to increase the rated power of the wind turbine by making it larger. However, it is not clear whether further upscaling of the existing wind turbines beyond the 5–7MW range is technically feasible and economically attractive. To address this question, this study uses 5, 10, and 20MW wind turbines that are developed using multidisciplinary design optimization as upscaling data points. These wind turbines are upwind, 3-bladed, pitch-regulated, variable-speed machines with a tubular tower. Based on the design data and properties of these wind turbines, scaling trends such as loading, mass, and cost are developed. These trends are used to study the technical and economical aspects of upscaling and its impact on the design and cost. The results of this research show the technical feasibility of the existing wind turbines up to 20MW, but the design of such an upscaled machine is cost prohibitive. Mass increase of the rotor is identified as a main design challenge to overcome. The results of this research support the development of alternative lightweight materials and design concepts such as a two-bladed downwind design for upscaling to remain a cost effective solution for future wind turbines.

Self-adaptive formation of uneven node spacings in wild bamboo.

Bamboo has a distinctive structure wherein a long cavity inside a cylindrical woody section is divided into many chambers by stiff diaphragms. The diaphragms are inserted at nodes and thought to serve as ring stiffeners for bamboo culms against the external load; if this is the case, the separation between adjacent nodes should be configured optimally in order to enhance the mechanical stability of the culms. Here, we reveal the hitherto unknown blueprint of the optimal node spacings used in the growth of wild bamboo. Measurement data analysis together with theoretical formulations suggest that wild bamboos effectively control their node spacings as well as other geometric parameters in accord with the lightweight and high-strength design concept.

Joining zone design for electromagnetically crimped connections

Space frames and multi-material structures are innovative designs to reduce the weight of a vehicle. But both lightweight design concepts have complex demands on joining technologies with the result that conventional processes are often pushed to their technological limits. Joining by electromagnetic crimping provides an interesting alternative to connect such structures without penetration or external heating. During electromagnetic crimping, pulsed magnetic fields are used to form a profile made out of an electrically conductive material into form-fit elements, like grooves, of the other joining partner. Thereby, an interlock is generated, which enables a load transfer. However, existing joint design methodologies require either extensive experimental studies or numerical modeling. To facilitate the connection design, an analytical approach for the prediction of the joining zone parameters with respect to the loads to be transferred is presented in this article. For the validation of the developed approach, experimental studies regarding the load transfer under quasi-static tension are performed. The major parameters considered in these investigations are the groove dimensions and its shape. In order to reduce the mass of a structure, hollow mandrels can be applied. To analyze how the reduced compressive strength of such inner connection elements influences the joining behavior and the load transfer of electromagnetically crimped connections, experimental studies are performed subsequent to the studies on the general groove parameters. Based on the obtained results, design strategies and a process window for the manufacturing of such joints are developed. To show the potential of electromagnetic form-fit joining, example connections joined in accordance with the established design guidelines are tested under quasi-static and cyclic loading.

Analytical methodology for the process design of electromagnetic crimping

Modern lightweight design concepts, like the space frame design and multi-material structures, have complex demands on joining technologies, and conventional processes are often pushed to their technological limits. An interesting alternative for connecting extruded aluminum profiles without heating or penetration is joining by electromagnetic crimping. Compared to adhesive bonding and welding, the process also requires a less extensive joining zone preparation. However, existing process design methodologies require either extensive experimental studies or sophisticated numerical modeling. Therefore, an analytical approach for the determination of process parameters, like the applied charging energy, is presented in this article. Besides groove geometry and workpiece properties, the model also considers the electrical characteristics of the electromagnetic forming equipment. Experimental studies of the joining process are performed to verify the developed model. Additionally, the electromagnetic crimping operation is numerically modeled for a more detailed analysis of this process.

Economically Viable Lightweight Design Concept for a Hybrid B-pillar

Dr.-Ing. Thomas Muhr is General Partner of the Mubea Group in Attendorn (Germany). Johannes Weber, B. Eng. is Project Leader at the Mubea Carbo Tech GmbH in Salzburg (Austria). Dipl.-Ing. (FH) Andreas Theobald is Team Leader within the CAE at the Edag Engineering AG in Fulda (Germany). Dr.-Ing. Martin Hillebrecht is Head of the Competence Center Lightweight Design, Materials and Technologies at the Edag Engineering AG in Fulda (Germany). Economically Viable Lightweight Design Concept for a Hybrid B-pillar

Innovative Lightweight Design Concepts for Hoods

Innovative Lightweight Design Concepts for Hoods

Lightweight Design Concept for a Vehicle with Low CO2 Emissions

Lightweight Design Concept for a Vehicle with Low CO2 Emissions

Toward a Lightweight Design Philosophy for High‐Speed Sealift Ships

AbstractThe US Navy's new Center for Innovation in Ship Design (CISD) completed in 2004 a Concept Formulation (CONFORM) study, under the sponsorship of the Naval Sea Systems Command, of a lightweight High‐Speed Sealift (HSS) Ship as part of the Navy's Sea Basing concept studies. The objective of the ship CONFORM study was to develop design concepts that would reduce weight in order to facilitate higher speeds. These lightweight design concepts were looked at in the context of total‐ship concepts. CISD investigated both near‐term product and process technologies, where the Navy would have enough confidence to begin the design of a lightweight high‐speed ship within 5 years. Importance was given to developing a lightweight, high‐speed design philosophy consisting of a Sea Basing “System of Systems” (SOS) approach driven by a Concept of Operations (CONOPS). This top‐down approach, or systems architecting, included functional analyses to determine necessary military capabilities, functional allocation of these capabilities to the various component systems of the Sea Basing System, and concept design analyses to determine the best total ship architecture for a lightweight, HSS ship. Concurrent with the SOS top‐down approach was a bottom‐up approach of assessing emerging technologies that would enable optimum total ship architectures for lightweight, high‐speed ships. The ship CONFORM study was conducted by the Light Weight, Total Ship Architecture, Design Concepts Innovation Cell, a multi‐disciplinary team comprised of ship designers, structural engineers, shipbuilders, and student interns. By applying a top‐down, systems engineering process of functional analysis and functional allocation, the Innovation Cell quickly learned that the easiest way to reduce ship weight was to allocate ship functions to the Sea Base through Operational Innovations. The authors highlight that many traditional shipboard systems and equipment that a transport ship would normally carry to provide necessary services aboard the ship would have to be located on and provided by the Sea Base. Also, the derivation, rationale, and validity of every explicit and derived design requirement were questioned. Because hull structure is the largest contributor to full‐load displacement, emphasis was placed on taking advantage of new manufacturing technologies and joining methods such as laser welding to enable the development of near‐term, innovative, and lightweight structural design concepts such as sandwich panels. The authors discuss the significant weight reductions and cost/producibility aspects of these innovative structural design concepts, as well as the results of a peer review by the Navy's technical authorities. In addition to describing this lightweight, high‐speed design philosophy, rationale is also presented that leads to the overwhelming conclusion for the need to develop a near‐term, lightweight, high‐speed, oceangoing Innovative Naval Prototype ship. Technical aspects of the prototype ship are presented to support the objective to capitalize on large‐scale, transformational system technologies, such as long slender stabilized monohull forms, 60–70‐MW axial flow waterjets, and lightweight structures, in order to resolve important technical and operational problems that will enable significant gains in Sea Basing warfare capabilities.

The future of adhesive bonding as a joining technique

The future of structural adhesive bonding as a joining technique in automobile construction has only just begun. Modern lightweight design, safety and modular concepts can no longer do without adhesively bonded joints and the strength they provide in a crash scenario.