Prediction of holz pattern shifts in convergent beam diffraction

In general, diffraction patterns from the higher-order Laue zones are shifted with respect to the zero-order pattern. Expressions for the shift ( t ) have been derived in terms of the indices [u, v, w] of a zone, the interplanar spacing ( H ), and a reciprocal lattice vector [ g _L (hkl)] in a holz. The resulting vector possesses the direction of t in terms of a zolz reciprocal lattice vector and has a magnitude which is a fraction of that of the zolz vector. Hence, the calculation of t allows quantitative determination of the location of specific planes in a holz with respect to the zolz, thus simplifying the determination of plane indices consistent with those used in the zolz. The expressions for determining t for cubic, hexagonal close-packed (hep), tetragonal, orthorhombic, and monoclinic crystal types are presented in a table and, when applied, allow calculation of t expressed as a fraction of a zolz vector. An example for graphite is presented to illustrate the use of the equation, and t vectors for several zones for the simple cubic system are tabulated.     

Materialwissenschaftliche Analyse des Abbindeverhaltens von Holzklebstoffen am Beispiel von 1K-PUR

The curing of wood adhesives has so far been evaluated on a basis of parameters, which offer process optimization only to a small degree. However, the curing becomes analyzable in detail by using oscillation measurements and a test setup adapted to the bonding process. With time sweep measurements, the adhesion process can be divided into characteristic ranges of molecular and structural processes. This method is presented and analyzed using a polyurethane prepolymer for joining wood-based materials.     

Verbunddecken aus Stahlfaserbeton und Holz

Composite Floors made of Steel Fibre Reinforced Concrete and Timber For many years the timber‐concrete composite construction is known and approved particularly with regard to the revaluation and strengthening of timber beam ceilings. The benefits are an obvious increase of the load bearing capacity, a reduction of the deflection, a better vibration behaviour of the ceiling and an improvement of building physical properties like sound insulation and fire resistance. The reinforcement of the concrete slab is necessary, but leads to a large slab thickness in connection with the necessity of a sufficient concrete cover and to disadvantages during the execution of construction work. Therefore it is reasonable to replace the conventional reinforcement by steel fibres. This paper reports on two building projects and their associated experimental pre‐tests, in which steel fibre reinforced concrete was applied for the strengthening of timber beam ceilings.     

Langzeitverhalten geklebter Bauteile aus Holz und hochfestem Beton bei natürlichem Klima

Longterm‐behavior of glued full‐scale specimens made from wood and high performance concrete at natural climate conditions The advantages of the construction materials wood and concrete could be used effectively in wood‐concrete‐composite constructions. The composite structure shows optimized load carrying capacity, a better vibrational behavior, higher noise protection and a higher thermally activatable mass in comparison to constructions that are entirely made from wood. Mechanical fasteners or form fitting connections are state‐of‐the‐art for connecting timber to concrete. This leads to more or less flexible bond. By using the adhesive technology a ”rigid bond“ can be achieved and it is possible to combine the advantages of a ”dry construction method“ with the advantages of the prefabrication. The questions of the production technology and the short‐term behavior of glued wood‐concrete composite constructions were answered yet at the department of timber structures at the University of Kassel. Knowledge of long‐term behavior was missing for an application in construction practice. This was studied in the last three years in detail. The experimental und numerical investigations on full‐scale specimens and the conclusions for a practical application are reported in the following article.