TY - JOUR A1 - Dreßler, Martin A1 - Dombrowski, Felix A1 - Simon, Ulla A1 - Börnstein, Julian A1 - Hodoroaba, Vasile-Dan A1 - Feigl, Michael A1 - Grunow, Sabrina A1 - Gildenhaar, Renate A1 - Neumann, Martin T1 - Influence of gelatine coatings on compressive strength of porous hydroxyapatite ceramics N2 - Porous ceramics prepared by the foam replication technique have a high porosity and low mechanical stability. It has been reported that coating such porous ceramics with gelatin allows for an improved compressive strength. Little details regarding the influence of important gelatin parameters such as concentration, temperature and drying conditions as well as bloom number which is a measure of the gel rigidity, on this toughening effect are available. This paper investigates the influence of these parameters on compressive strength of gelatin coated porous hydroxyapatite ceramics. It was found that concentration in the gelatin sols has a marked impact whereas sol temperature, bloom number and differing conditions during subsequent drying have only little influence on the compressive strength of the coated ceramics. KW - Films KW - Composites KW - Strength KW - Apatite KW - Biomedical application PY - 2011 U6 - https://doi.org/10.1016/j.jeurceramsoc.2010.11.004 SN - 0955-2219 SN - 1873-619X VL - 31 IS - 4 SP - 523 EP - 529 PB - Elsevier Ltd. CY - Oxford AN - OPUS4-23216 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eisenacher, Germar A1 - Scheidemann, Robert A1 - Neumann, Martin A1 - Droste, Bernhard A1 - Völzke, Holger T1 - Dynamic crushing characteristics of spruce wood under large deformations N2 - An extensive series of large deformation crushing tests with spruce wood specimens was conducted. Material orientation, lateral constraint and loading rate were varied. Regarding material orientation, a reduction in the softening effect and the general force level was observed with a higher fiber-load angle. A comparison with characteristics gained by application of Hankinson's formula showed discrepancies in compression strength and the beginning of the hardening effect. Lateral constraint of the specimens caused a multiaxial stress state in the specimens, which was quantified with the applied measuring method. Further, a higher force level compared to specimens without lateral constraint and significant hardening effect at large deformations resulted. Thus, the influence of a multiaxial stress state on the force level could be determined. An increase in the loading rate led to higher force levels at any displacement value and material orientation. KW - Crushing test KW - Dynamic crushing characteristics KW - Spruce wood KW - Lateral constraint KW - Multiaxial stress state KW - Hankinson's formula PY - 2013 U6 - https://doi.org/10.1007/s00226-012-0508-5 SN - 0043-7719 SN - 1432-5225 VL - 47 IS - 2 SP - 369 EP - 380 PB - Springer CY - Berlin AN - OPUS4-27743 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Martin A1 - Herter, Jürgen A1 - Droste, Bernhard A1 - Hartwig, S. T1 - Compressive behaviour of axially loaded spruce wood under large deformations at different strain rates N2 - Impact limiting components of packages for the transport of radioactivematerials are often designed as wood filled steel constructions. Wood absorbs major part of the impact energy in order to minimise the impact load acting upon the containment. Dynamic impact experiments with wood filled impact limiters showed different crushing mechanisms for axially loaded wood depending on their lateral constraint. Tests on spruce wood samples (Picea abies) were performed in order to clarify the influence of strain rate from static to 30 s-1 on a) compression strength, b) stress at a global strain level of 50%, and c) energy absorption capacity at 50% deformation, including statistical evaluation of the results. Results were as follows: strain rate increase led to significantly higher compression strength, stress and strain energy at a strain level of 50%. Lateral strain restriction had no effect on compression strength; it had a significant effect on stress and strain energy at strain level of 50%. Therefore, the definition of a general yield curve for wood under large deformations is not possible, the yield curve has to be chosen taking into account lateral constraints. KW - Compression KW - Wood KW - Spruce KW - Picea abies KW - Impact PY - 2011 U6 - https://doi.org/10.1007/s00107-010-0442-x SN - 0018-3768 VL - 69 IS - 3 SP - 345 EP - 357 PB - Springer CY - Berlin ; Heidelberg AN - OPUS4-22980 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -