During surgical procedures, the heat development of bone cutting can lead to thermal cell necrosis and secondary implant instability. Therefore, fundamental knowledge on heat development and temperature control is crucial. This paper investigates the basic principles of the machining of cortical bone in an orthogonal cutting process. Cutting forces, temperature elevation and chip formation were measured in real time for two different rake angles and six different cutting depths. A non-linear relationship between cutting depth and cutting forces as well as temperature elevation was found. A linear correlation between cutting forces and temperature elevation of both bone chip and workpiece was determined (R 2 = 0.8697) An increasing rake angle lowered cutting forces and temperature elevations significantly and was explained using a fracture mechanics approach. Additionally, a new method to calculate the fracture toughness of (quasi-)brittle materials from orthogonal cutting tests was introduced. Recent advances in numerical modeling of bone cutting have been summarized by Marco et al. [15] but there are only limited models for the cutting of brittle or quasi-brittle materials [16].However, compared to metals, cortical bone is a very different material with a quasi-brittle and not ductile behavior. It is anisotropic with osteons (∅ 200 µm)

No abstract

No abstract

Air traffic is expected to double over the next 20 years and Flightpath 2050 targets to a 70 % reduction of CO2 and a 90 % reduction of NOx. Optimization of future aircraft engines often is dominantly driven by a focus on the reduction of fuel burn and emissions during operation. To identify additional environmental improvement potential a full Life Cycle Analysis (LCA) shall be aspired also including Materials, Processes and Resources, Manufacture and Production, Lifetime Services as well as Reuse, End-of-Life and Recycling. Core engine components, for example integral rotors, are comprised of Titanium-or Nickel-alloys and require complex manufacturing processes. A geometry design model of a compressor blisk is introduced which is employed as basis for a future LCA approach focusing on materials, processes and resources as well as manufacture and production. The model is a carrier for challenging manufacturing features such as large blade twist, high aspect ratio and small blade gaps. In addition to the geometry model, a first set of multiple technology scenarios and their process chains will be introduced which will serve as base for a future LCA.