Wood - The Internal Optimization of Trees

Mit mehr als 100 schönen wie amüsanten Zeichnungen und viel didaktischem Geschick zeigen die Autoren, daß die Innenarchitektur der Bäume optimal an die Belastung angepaßt ist. Die Holzqualität ist da am höchsten, wo dem Baum die meiste Gefahr droht, wo also in seinem Inneren die größten Spannungen wirken.

With more than 100 drawings, both beautiful and amusing, and with a lot of didactic skill the authors show that the interior architecture of trees is adapted to external loading in an optimum way. Wood quality is highest at places of maximum loading.

Contenu
1 Introduction.- 2 Mechanical Fundamentals.- 2.1 External Loading and Internal Stresses.- 2.2 Thermal Expansion and Thermal Stresses.- 2.3 The Finite-Element Method (FEM).- 2.4 Notches and Notch Stresses The Component Killers.- 2.5 Crack Propagation.- 2.6 The Main Mechanical Aspects.- 3 The Mechanical Self-Optimization of Trees Five Theorems.- 3.1 The Five Theorems.- 4 The Principle of Minimum Lever Arms.- 4.1 Negative Gravitropism.- 4.2 The Flexibility Strategy.- 5 The Axiom of Uniform Stress.- 5.1 The Undisturbed Design.- 5.2 Repair Growth.- 5.3 Computer-Aided Optimization CAO.- 6 Parallel Fiber and Force Flow Arrangement.- 6.1 The Principal Stress Trajectories are Shear-Free Lines.- 6.2 Computer-Aided Internal Optimization CAIO.- 6.3 Spindle Shapes Advantages and Problems.- 6.4 Fiber Deviations.- 6.4.1 Mechanically Controlled Spiral Grain.- 6.4.2 Genetically Programmed Spiral Grain.- 6.4.3 The Risks of Spiral Grain.- 7 Tree Rings and Force Flow.- 7.1 Longitudinal Tree Ring Arrangement.- 7.2 Tangential Tree Ring Arrangement.- 8 Growth Stresses.- 8.1 Qualitative Description.- 8.2 Longitudinal Stresses.- 8.3 Lateral Stresses.- 8.4 Selected Techniques for Measuring Growth Stresses.- 8.4.1 Visual Evaluation.- 8.4.2 Measurement of Growth Stresses with an Increment Borer.- 8.4.3 Growth Stress Measurement with Prismatic Samples.- 8.4.4 Growth Stress Measurement Between Two Pocket Holes.- 8.4.5 Single-Hole Growth Stress Measurement.- 8.4.6 Tangential Growth Stress Measurement on Radial Saw Cuts.- 9 Stress-Controlled Strength Distribution.- 9.1 The Wood-Concrete Analogy.- 9.2 Radial Transverse Strengths and Hazard Beams.- 9.3 Tangential Transverse Strengths in Leaning Trees.- 9.4 Strengths in the Residual Walls of Hollow Trees.- 10 Cracks.- 10.1 FrostCracks.- 10.2 Shear Cracks.- 10.3 Enclosed Bark.- 10.4 Hazard Beams.- 10.5 Ring Shakes.- 10.6 Grown Cracks on the Upper Sides of Branch Joints.- 10.7 T-Cracks.- 10.8 Drought Cracks.- 11 Final Remarks Review and Outlook.- Reference.