@misc{12918, author = {{Frühwald-König, Katja}}, location = {{Merzenich-Bürgewald}}, title = {{{Holz = Baustoff der Zukunft! Moderner Holzbau: Neue Werkstoffe und Bearbeitungsverfahren - Neue Wege gehen und Grenzen überwinden}}}, year = {{2025}}, } @misc{12919, author = {{Frühwald-König, Katja}}, location = {{NRW-Stage auf der Ligna Hannover}}, title = {{{Impulsvortrag auf der Podiumsveranstaltung}}}, year = {{2025}}, } @misc{13480, author = {{Frühwald-König, Katja}}, location = {{Rheda-Wiedenbrück}}, title = {{{Holzwerkstoffe aus Monokotyledonen - Potenziale, Herausforderungen und Zukunftsperspektiven}}}, year = {{2025}}, } @misc{11789, author = {{Frühwald-König, Katja}}, location = {{Lemgo}}, title = {{{Forestry and Timber Industry in the Context of the Bioeconomy of North Rhine-Westphalia}}}, year = {{2024}}, } @misc{11792, abstract = {{To facilitate the drying process and enhance the properties of oil palm wood, oil palm boards were mechanically pre-dewatered and thermo-hygro-mechanically (THM) densified. The thickness of the boards was reduced with compression ratios of 40%, 60% and 75%. Since densified wood tends to recover from compression, especially under humid conditions, this study examined the set-recovery and the hygroscopic behavior of THM densified oil palm wood. The equilibrium moisture content (EMC), differential swelling and swelling coefficient, linear swelling and shrinkage as well as the differential swelling anisotropy were determined under climate conditions with different relative humidity (RH) (20°C/35% RH, 20°C/65% RH and 20°C/85% RH). The maximum swelling was measured after water soaking and the remaining set-recovery was evaluated after re-drying at 103°C. The EMC was reduced by the THM process by around 20%. In the direction of compression (thickness), the densified specimens show higher values for all analyzed swelling and shrinkage parameters than the undensified specimens from the equivalent position within the trunk. The maximum swelling in thickness of 22–38% during water soaking is mostly reversed by shrinkage during re-drying and a comparably low remaining set-recovery of 3–8% is measured at oven dry condition.}}, author = {{Kölli, Nathan and Frühwald-König, Katja and Hackel, Martin}}, booktitle = {{Wood Material Science & Engineering}}, issn = {{1748-0280}}, keywords = {{Densification, set-recovery, swelling and shrinkage}}, pages = {{1--12}}, publisher = {{Taylor & Francis}}, title = {{{Hygroscopic behavior of thermo-hygro-mechanical (THM) densified oil palm sawn timber}}}, doi = {{10.1080/17480272.2024.2381100}}, year = {{2024}}, } @misc{11823, abstract = {{This study investigates the macromechanical and micromechanical behavior of oil palm wood by testing the elastomechanical properties in bending, compression parallel and perpendicular and tension parallel and perpendicular to the vascular bundles of small-size test specimen depending on the position within the trunk, the density and the number of vascular bundles per unit area as well as the plantation site. All properties tested show a much higher exponential increase with the density, following power law relationships with exponents > 1, than common wood species and a significant gradient over both trunk height and cross section. Oil palm wood can be seen as a unidirectional long-fiber-reinforced bio-composite, if vascular bundles are considered as reinforcements (fibers) and parenchymatous ground tissue as matrix. The adapted rule-of-mixture based on the number of vascular bundles per unit area can be confirmed for the density, but not for the tensile properties, because the number of vascular bundles per unit area and share of fibers within the bundles is greater in the periphery than in the trunk central tissue. Furthermore, cell wall thickening over time is more pronounced in the peripheral than in the central tissue and more at the bottom than near the top. Different from small test specimens from common wood species, the compression strength exceeds the tensile strength: fc,0 : fm : ft,0 is 1.4 : 2.2–1.2 : 1. The performance indices for minimum weight design by Ashby and coworkers are comparable to that for coconut and date palm wood.}}, author = {{Frühwald-König, Katja and Heister, Lena}}, booktitle = {{European journal of wood and wood products : Holz als Roh- und Werkstoff }}, issn = {{1436-736X}}, keywords = {{MECHANICAL-PROPERTIES, STEM, FAILURE}}, publisher = {{Springer}}, title = {{{Macro- and micromechanical behavior of oil palm wood (Elaeis guineensis JACQ.): tensile, compression and bending properties}}}, doi = {{https://doi.org/10.1007/s00107-024-02131-w}}, year = {{2024}}, } @misc{12028, abstract = {{Since the early 2000s, forest owners in Central Europe have increasingly planted Nordmann fir (Abies nordmanniana (STEV.) SPACH) and Noble fir (Abies procera REHD.) for Christmas trees, intending to convert them into high forests. Climate-related damage, especially since 2018, has significantly reduced spruce populations, requirering a shift towards climate-adaptable tree species in future forests. Additionally, to reduce CO2 emissions from construction, there's a push for expanding timber construction, requiring non-spruce species for load-bearing products and applications. Although Nordmann and Noble fir are potential alternatives to spruce, they are not yet integrated into European standardization for load-bearing construction. Therefore, an assessment of German-origin Nordmann and Noble fir for use in glued laminated building products (GLT and CLT) is underway. Kiln-dried lamellas are graded visually and by machine using longitudinal vibration, with selected lamellas tested for tensile strength. Various mechanical properties are determined using non-destructive and destructive methods to establish input parameters for Finite Element Analysis (FEA). }}, author = {{Frühwald-König, Katja and Hackel, Martin and Kipp, Dennis and Lüke, Karin and Stracke, Felix Leonard and Burghaus, Noah and Wieland, Stefanie}}, booktitle = {{Proceedings of the 23rd International Nondestructive Testing and Evaluation of Wood Symposium}}, keywords = {{Nordmann fir, Noble fir, grading, elastomechanical properties, ultrasonic testing, vibration measurement}}, location = {{Campinas, Sao Paulo, Brasil}}, pages = {{192--204}}, publisher = {{United States Department of Agriculture (USDA)}}, title = {{{Nordmann and Noble fir Lamellas for Structural Purposes – Grading and Determination of Elastomechanical Properties by Non-Destructive and Destructive Testing}}}, year = {{2024}}, } @misc{12029, abstract = {{Following storm and calamity events in Europe since the early 2000s, many forest owners decided to establish Christmas tree plantations featuring Nordmann fir (Abies nordmanniana (STEV.) SPACH) and Noble fir (Abies procera REHD.), which are currently transformed into high forests. Climate-related forest damages and calamities result in significant depletion of spruce since 2018. Future forests should be characterized by a climate-adaptable variety of tree species. Nordmann and Noble fir represent possible alternatives to spurce, however from European origin they are not yet integrated into European standardization and therefore cannot be used for load bearing construction products. Consequently, an assessment of the potential of Nordmann and Noble fir of German origin for use in Glued Laminated Timber (GLT) is conducted. Selected tensile, compression, shear, and bending properties in various anatomical directions are determined on small, defect-free samples with destructive and non-destructive methods to establish input parameters for Finite Element Analysis (FEA).}}, author = {{Hackel, Martin and Frühwald-König, Katja and Burghaus, Noah and Stracke, Felix Leonard}}, booktitle = {{Proceedings of the 20th Annual Meeting of the Northern European Network for Wood Science and Engineering (WSE2024)}}, location = {{Edinburgh, Scotland}}, publisher = {{Edinburgh Napier University }}, title = {{{Nordmann and Noble fir -Determination of Elastomechanical Properties by Non-Destructive and Destructive Testing}}}, year = {{2024}}, } @misc{11112, author = {{Frühwald-König, Katja}}, location = {{Großenmarpe}}, title = {{{Potenziale der Nutzung klimastabiler Holzarten – Was braucht es für die Nutzung unserer zukünftigen Holzarten?}}}, year = {{2024}}, } @misc{11113, abstract = {{When oil palm lumber is considered for load-bearing products such as glued laminated timber (GLT), defined strength and stiffness values are required. In this investigation, combined GLT from oil palm wood is tested in compression parallel and perpendicular and glulam lamellas in tension parallel to the vascular bundles. Strength and Young´s modulus in compression and tension parallel increase with the density by power law relationship. In contrast to dicotyle­dons, the strength in construction size exceeds that of small, defect-free test specimens (compression strength perpendicular), are in the same range (tensile and bending strength parallel) or only a little below (compression strength parallel). The specimen size does not influence the strength. The ratio of fc,0 : fm : ft,0 is 1.2 : 0.8 … 1.7 … 2.6 : 1 and fc,0 : fc,90 = 2.7 … 13.0 … 32.6 : 1 for ρ = 200 … 400 … 600 kg/m³; the ratio of Ec,0 : Em : Et,0 is 1.2 : 1.3 : 1 for ρ = 400 kg/m³. Ashby´s performance indices for minimum weight design rise with the density; the strength-density performance indices are comparable or only slightly lower than that for structural size softwood, whereas the modulus-density performance indices are much lower. The challenge in use of oil palm wood for load-bearing construction products is the low stiffness.}}, author = {{Frühwald-König, Katja and Heister, Lena}}, booktitle = {{Wood material science and engineering}}, issn = {{1748-0280}}, keywords = {{Oil palm wood, compression, tension, strength, young’s modulus, digital image correlation, glued laminated timber}}, number = {{5}}, pages = {{1101--1116}}, publisher = {{Taylor & Francis}}, title = {{{Compression properties of glued laminated timber and tensile properties of gluelam lamellas from oil palm wood}}}, doi = {{10.1080/17480272.2024.2303627}}, volume = {{19}}, year = {{2024}}, } @misc{11114, abstract = {{Oil palm wood is mainly low in density and since strength and stiffness correlate with density, this study aimed to enhance the properties of oil palm wood through thermo-hygro-mechanical (THM) densification. In contrast to other studies using small laboratory-sized specimens, this study examined the densification of oil palm boards in sawn timber dimensions of 2.0 m length. Modulus of elasticity (MOE) and modulus of rupture (MOR) in bending, shear strength and shear modulus parallel by two-plate shear test and Young’s modulus in the three main directions as well as shear modulus in the three planes by ultrasonic testing were determined at densified and undensified specimens. The bending properties were increased to considerably higher levels and a compression ratio of 60% showed higher MOE and MOR values than that of 40%; whereas for boards of the inner part of the trunk, a compression ratio of 60% showed better results than that of 75%. The shear properties were only slightly increased through densification. Densification can improve the properties of oil palm wood. However, the wide range of density and properties found in natural oil palm wood is also present in densified oil palm wood.}}, author = {{Kölli, Nathan and Frühwald-König, Katja}}, booktitle = {{Wood material science and engineering }}, issn = {{1748-0280}}, keywords = {{Bending strength, densification, e-modulus, g-modulus, shear strength}}, pages = {{1--18}}, publisher = {{Taylor & Francis}}, title = {{{Elasto-mechanical properties of thermo-hygro-mechanical (THM) densified oil palm sawn timber}}}, doi = {{10.1080/17480272.2024.2317977}}, year = {{2024}}, } @misc{9188, author = {{Heister, Lena and Frühwald-König, Katja}}, booktitle = {{Proceedings of 2nd World Conference on Byproducts of Palms and Their Applications}}, editor = {{Jawaid, Mohammad and Midani, Mohamad and Khiari, Ramzi}}, isbn = {{978-981-19-6194-6}}, issn = {{2662-317X }}, location = {{online}}, pages = {{29--44}}, publisher = {{Springer Nature}}, title = {{{Glued Laminated Timber from Oil Palm Timber – Beam Structure, Production and Elastomechanical Properties}}}, doi = {{10.1007/978-981-19-6195-3_3}}, volume = {{19}}, year = {{2023}}, } @misc{10332, author = {{Frühwald-König, Katja}}, location = {{Oberkochen}}, title = {{{Holz = Baustoff der Zukunft! }}}, year = {{2023}}, } @misc{10333, abstract = {{The wood from oil palm trunks exhibits significant variations in distribution of structural tissue, density and elastomechanical properties across and along the trunk. Its reliable, safe, and economic usage for load-bearing purposes, such as glued laminated timber (GLT), requires a precise definition of its elastomechanical properties through appropriate strength grading procedures. Oil palm lumber is strength graded according to its density using an X-ray technique in which 50 % of the lamellas are ripped, graded, edge glued and therefore density homogenized, and 50 % are cut only according to their geometry. Lamellas are tested in tension parallel to the vascular bundles; combined GLT is produced from strength-graded lamellas and tested in bending parallel and compression parallel and perpendicular to the vascular bundles. The characteristic strength values for C10 and C14 according to EN 338 are achieved. A correlation between density and elastomechanical properties is estab-lished. GLT from density-homogenized lamellas achieve higher bending properties than from lamellas with a “natural” density gradient across the width.}}, author = {{Frühwald-König, Katja}}, booktitle = {{Timber for a livable future : World Conference on Timber Engineering : WCTE 2023 : 19-22 June 2023, Oslo, Norway }}, editor = {{Nyrud, Andres Q. and Malo, Kjell Arne and Nore, Kristine}}, isbn = {{9781713873297}}, keywords = {{Oil palm lumber, glue laminated timber, GLT, strength grading, elastomechanical properties}}, location = {{Oslo, Norway}}, pages = {{638--646}}, publisher = {{Curran Associates, Inc. }}, title = {{{Elastomechanical Properties of Glued Laminated Timber made of Strength Graded Oil Palm Lumber}}}, doi = {{https://doi.org/10.52202/069179-0087}}, year = {{2023}}, } @misc{10334, author = {{Frühwald-König, Katja}}, location = {{Olsberg}}, title = {{{Technische Eigenschaften der Birke und Einsatz im Ingenieurholzbau}}}, year = {{2023}}, } @misc{10335, author = {{Frühwald-König, Katja}}, title = {{{Die Holzbauinitiative der Bundesregierung}}}, year = {{2023}}, } @misc{10336, author = {{Frühwald-König, Katja and Wieland, Stefanie}}, booktitle = {{ 5. Aachener Holzbautagung 2023}}, location = {{Aachen}}, publisher = {{Aachen}}, title = {{{Wald im Klimawandel - Einsatz von Birke im Holzbau}}}, year = {{2023}}, } @misc{10709, author = {{Frühwald-König, Katja}}, location = {{Arnsberg}}, title = {{{Wald im Klimawandel - Neue Holzarten für das Bauen mit Holz}}}, year = {{2023}}, } @misc{10874, author = {{Frühwald-König, Katja}}, location = {{Riyadh, Saudi-Arabien}}, title = {{{Mechanical Dewatering of Oil Palm Lumber to Reduce Costs and Improve Quality.}}}, year = {{2023}}, } @misc{10875, author = {{Frühwald-König, Katja}}, location = {{Riyadh, Saudi-Arabien}}, title = {{{Cross Laminated Timber (CLT) made of Oil Palm Wood (Elaeis guineensis JACQ.)}}}, year = {{2023}}, } @misc{8401, abstract = {{200 million m³ oil palm trunks per year are still a “waste by-product”. For generating added-value, material modelling and product optimization and therefore knowledge of the elastic properties are required. Apart from Young´s modulus parallel to the vascular bundles, the elastic properties of oil palm wood are not known. The applicability of ultrasonic testing (time of flight of three longitudinal, six shear and three quasi-shear wave measurements) for the characterization of all 12 elastic constants of oil palm wood hav-ing various densities was investigated under the assumption of an orthotropic material behavior. For the evaluation, the simplified uncorrected and the full stiffness inversion method were used. The lack of correlation between the density and the ultrasonic velocity when using flat transducers questions the applicability of this method for oil palm wood.}}, author = {{Frühwald-König, Katja and Faust, Benedikt}}, booktitle = {{Proceedings 22nd International Nondestructive Testing and Evaluation of Wood Symposium}}, location = {{Quebec City, Canada}}, pages = {{29--39}}, publisher = {{U.S. Department of Agriculture, Forest Service, Forest Products Laboratory}}, title = {{{Evaluation of Elastic Constants of Oil Palm Wood using Ultrasonic Measurement}}}, year = {{2022}}, } @misc{8926, author = {{Frühwald-König, Katja}}, location = {{Lichtenau/Westfalen}}, title = {{{Aktueller/künftiger Holzbedarf und Holzverwendung (stofflich und energetisch)}}}, year = {{2022}}, } @misc{8927, author = {{Wieland, Stefanie and Frühwald-König, Katja}}, location = {{Lichtenau/Westfalen}}, title = {{{Wald im Klimawandel - Neue Holzarten für das Bauen mit Holz}}}, year = {{2022}}, } @inbook{10593, abstract = {{Due to shorter rotation cycles compared to other palm species, oil palm wood has lower densities, a wider density range (150–600 kg/m3 dry), and a high moisture content. The moisture content varies, reversely to the density, with the highest values of up to 600% at the trunk core, especially at the top of the palm trunk. Kiln drying material with such low density, very high moisture content and high sugar and starch content is difficult and often produces drying defects such as cell collapse, cracks, and mold. Mechanical dewatering of wet oil palm lumber in an unheated double roller press reduces the water content and generates sugar-containing pressed water (sap) that could be used as a source for biochemicals. The share of mechanically removed water varied from 1 to >54% of the total water removed from wet to dry state (at 20 °C, 65% rh). Center boards from the top of the trunk had the highest dewatering rates while boards from the periphery at the bottom of the trunk (high density, low water content) showed the lowest.}}, author = {{Frühwald-König, Katja and Kölli, Nathan and Frühwald, Arno}}, booktitle = {{ Proceedings of 2nd World Conference on Byproducts of Palms and Their Applications }}, editor = {{Jawaid, Mohammad and Midani, Mohamad and Khiari, Ramzi}}, isbn = {{978-981-19-6194-6 }}, issn = {{2662-3161}}, location = {{Kuala Lumpur, Malaysia}}, publisher = {{Springer Nature Singapore}}, title = {{{Mechanical Dewatering of Wet Oil Palm Lumber Prior to Press-Drying}}}, doi = {{https://doi.org/10.1007/978-981-19-6195-3_2}}, year = {{2022}}, } @inproceedings{6913, author = {{Frühwald, Arno and Frühwald-König, Katja and Loh, Yueh Feng}}, location = {{online}}, title = {{{Future Potential of Palm (Trunk) Fiber in Supplementing Timber: Quantities, Techniques, Challenges, Opportunities}}}, year = {{2021}}, } @inproceedings{6940, author = {{Frühwald-König, Katja}}, location = {{online}}, title = {{{Properties of Oil Palm Wood Relevant for Material Use}}}, year = {{2021}}, } @inproceedings{6941, author = {{Frühwald-König, Katja and Heister, Lena}}, location = {{online}}, title = {{{Grading of OP-Lumber – Techniques and Chances for Up-Grading Materials}}}, year = {{2021}}, } @inproceedings{6943, author = {{Heister, Lena and Frühwald-König, Katja}}, location = {{online}}, title = {{{GLT from Oil Palm Wood - Build-Up, Production and Elastomechanical Properties}}}, year = {{2021}}, } @inproceedings{6944, author = {{Frühwald, Arno and Frühwald-König, Katja}}, location = {{online}}, title = {{{Coconut Wood: Properties, Processing and Products}}}, year = {{2021}}, } @inproceedings{6946, author = {{Frühwald-König, Katja}}, location = {{Düsseldorf}}, title = {{{Mit Holzprodukten nachhaltig in die Zukunft bei veränderten Holzsortimenten}}}, year = {{2021}}, } @misc{10703, author = {{Frühwald-König, Katja}}, location = {{online}}, title = {{{Was kann Holz - außer klimafreundlich?}}}, year = {{2021}}, } @inproceedings{6947, author = {{Frühwald-König, Katja}}, location = {{Portoroz / Slowenien (online)}}, title = {{{Mechanical Properties versus Structure of Oil Palm Wood (Elais gueneensis Jacq.)}}}, year = {{2020}}, }