12. Material Behavior

… under Operating Loads

This chapter deals with the interaction of material properties and engine-specific loads that are relevant to damage (Fig. "A pplication specific demands on aeroengines").
Comprehensively seen, turbine engines can probably be considered to be the most demanding technical machines. The spectrum of factors that affect them includes:

• Mechanical loads (constant, LCF, HCF, shocks)
• Thermal stress (from very low temperatures in the compressor to extremely high temperatures in the hot parts)
• Operating times (civilian overhaul intervals of several 10,000 hours)
• Atmospheric influences (corrosion, erosion, lightning, hail; see Volume 1)

Despite these demands, engine parts must be as safe as possible at the lowest possible weight, high degrees of performance (aerodynamic, thermodynamic, mechanical), and at the limits of current strength tolerances (low weight demands, low safety factors).
Taking advantage of engine part properties near tolerance limits is only possible while maintaining the most stringent quality standards and safe design (understanding the loads and damage mechanisms that determine the life spans of the engine parts), while also using stable, optimized manufacturing processes and extensive experience.
Therefore, it is natural that, in the interest of preventing damage, turbine engine engineering must intensively concern itself with damage-relevant material behavior under operating conditions and loads.