Mechanical Behavior of Materials

• Prof. Dr.-Ing. habil. Benoit Merle

• 4 SWS lecture with hands-on sessions (6 ECTS)
• Language: english
• Time: TBA

• B.Sc. / M.Sc. Maschinenbau, or Wirtschaftsingenieurwesen mit Schwerpunkt Maschinenbau
• Vertiefung Nachhaltige Werkstoffe und Fertigungsverfahren (ab dem 5. Semester)
• Erasmus students

Whether in aerospace, energy generation, or automotive design, materials determine the efficiency, durability, and safety of components. Selecting the right material and developing better ones both require a quantitative understanding of the mechanical behavior of materials across length scales, from the atomic scale to the manufactured component.

This module explains the mechanisms governing deformation, fracture, fatigue, and creep and shows how this knowledge is used to predict the service life of real components and to design nextgeneration materials.

Topics covered:

• Fundamentals: stress and strain, engineering vs. true values, mechanical testing methods and their limitations
• Elasticity: atomistic origin, Hooke's law, elastic anisotropy, textured polycrystals, composites
• Viscoelasticity: rheological models, stress relaxation, damping
• Plasticity: yield criteria, flow curves and hardening laws, Considère criterion and necking, Bauschinger effect, plastic anisotropy and formability
• Dislocations: Burgers vector, dislocation types, Peach–Koehler force, Taylor hardening
• Deformation of crystalline materials: slip systems in fcc, bcc and hcp, critical resolved shear stress, Schmid factor, single and multiple slip, Taylor factor, texture effects, twinning
• Strengthening mechanisms: work hardening, solid-solution and precipitation hardening, Orowan bypass, strength–ductility trade-off, Hall–Petch relation
• Fracture: theoretical strength, Irwin and Griffith criteria, linearelastic and elastic-plastic fracture mechanics, K, J and CTOD, R-curves, brittle-to-ductile transition, Weibull statistics, toughening mechanisms
• Fatigue: S–N curves, Basquin and Coffin–Manson laws, crack initiation and Paris crack-growth law, damage-tolerant design, corrosion fatigue and hydrogen embrittlement
• Creep and strain-rate dependence: creep curves, power-law and diffusional creep, grain-boundary sliding, deformationmechanism maps, Larson–Miller extrapolation, activation energy and activation volume, superalloys

The lecture is accompanied by an integrated exercise class in which the concepts are applied hands-on, including computer-lab sessions with Jupyter notebooks, problem classes, and visits to the mechanical testing laboratories.

Upon successful completion, students will be able
to: 

• explain the concept of common mechanical properties
• link mechanical properties with microstructural processes and deformation mechanisms
• apply materials science properties to predict deformation and failure of technical components
• select materials for specific applications
• conduct damage analyses using case studies