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Thomas Keller - One of the best experts on this subject based on the ideXlab platform.
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fracture in complex Balsa cores of fiber reinforced polymer sandwich structures
Construction and Building Materials, 2014Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:Fracture in the complex Balsa cores of fiber-reinforced polymer (FRP) sandwich beams was analyzed. The cores were composed of high- and low-density Balsa layers separated by a circular adhesive interface or FRP arch. The Balsa layers were cut from panels which consisted of Balsa blocks adhesively bonded together. Failure in the beams was initiated by cracks propagating through the Balsa core thickness. The crack locations could be predicted using the Tsai-Wu failure criterion. Cracks initiated in the lowest density blocks due to their low fracture toughness. In mixed-mode fracture, crack propagation in the radial longitudinal (RL) plane prevailed due to the low fracture toughness in RL fracture of Mode I. In pure Mode II, propagation occurred in the RL and TL (transverse longitudinal) planes to the same extent since the toughness in RL and TL fracture is similar. Cracks were not able to propagate through the transverse adhesive joints between blocks if the bonding was good. If however the bonding was poor, interface failure occurred and cracks could propagate through the adhesive layer. (C) 2014 Elsevier Ltd. All rights reserved.
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structural limits of frp Balsa sandwich decks in bridge construction
Composites Part B-engineering, 2014Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:The span limits of two glass fiber-reinforced polymer (GFRP) bridge concepts involving GFRP-Balsa sandwich plates are discussed. The sandwich plates were either used directly as slab bridges or as decks of a hybrid sandwich-steel girder bridges. In the latter case, the potential of the sandwich decks to replace reinforced concrete (RC) decks was also evaluated. Taking the limits of manufacturing into account (800 mm slab thickness), maximum bridge spans of approximately 19 m can be reached with FRP-Balsa sandwich slab bridges, if a carbon-FRP (CFRP) arch is integrated into the Balsa core. Above this limit, hybrid sandwich-steel girder bridges can be used up to spans of 30 m. RC deck replacement requires timber and steel plate inserts into the Balsa core above the steel girders. GFRP-Balsa sandwich slabs or decks exhibit full composite action between lower and upper face sheets.
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frp Balsa composite sandwich bridge deck with complex core assembly
Journal of Composites for Construction, 2013Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:The aim of this work was to investigate to what extent the performance of a glass fiber-reinforced polymer (GFRP) sandwich slab-bridge with a uniform high-density Balsa core could be improved in terms of structural efficiency and weight by using a more complex core assembly. This core consisted of high-density and low-density Balsa and a fiber-reinforced polymer (FRP) arch inserted into the Balsa high/low density interface. Quasi-static load-bearing experiments on sandwich arch-beams with complex core assemblies under symmetric four-point and asymmetric three-point loading were performed. The FRP arch reduced the force in the upper face sheet in the mid-span region and thus prevented compression failure of the latter, which led to a higher ultimate load. It also contributed to the shear resistance by up to 20% for symmetric loading. The best overall performance in terms of structural efficiency (stiffness and resistance) and weight resulted from a core configuration with a GFRP arch between an upper high-density and lower low-density Balsa core. (C) 2013 American Society of Civil Engineers.
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shear mechanical characterization of Balsa wood as core material of composite sandwich panels
Construction and Building Materials, 2013Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:An experimental study was performed using Iosipescu specimens to evaluate the effects of parameters such as shear plane, density and adhesive joints on the shear stiffness and strength of Balsa wood panels as well as the variation of ductility with respect to the shear planes. The shear planes exerted a significant effect on shear stiffness and strength. Highest values were Obtained for the shear plane parallel to the end grain, intermediate values for the plane parallel to the flat grain and lowest values for the plane transverse to the flat grain. Shear stiffness and strength increased with increasing density of the Balsa. The thin adhesive joints in the Balsa panels between the lumber blocks increased the shear stiffness and strength with one exception. The strength of specimens with the shear plane transverse to the flat grain was reduced because of a change in the failure mode. Due to plastic deformations in the tracheids, specimens with shear planes parallel to the end grain and transverse to the flat grain exhibited significant ductility. The ductility of specimens with the shear plane parallel to the flat grain was less pronounced as it was affected by the relatively brittle lignin material of the middle lamella. (C) 2012 Elsevier Ltd. All rights reserved.
Michael Oseiantwi - One of the best experts on this subject based on the ideXlab platform.
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fracture in complex Balsa cores of fiber reinforced polymer sandwich structures
Construction and Building Materials, 2014Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:Fracture in the complex Balsa cores of fiber-reinforced polymer (FRP) sandwich beams was analyzed. The cores were composed of high- and low-density Balsa layers separated by a circular adhesive interface or FRP arch. The Balsa layers were cut from panels which consisted of Balsa blocks adhesively bonded together. Failure in the beams was initiated by cracks propagating through the Balsa core thickness. The crack locations could be predicted using the Tsai-Wu failure criterion. Cracks initiated in the lowest density blocks due to their low fracture toughness. In mixed-mode fracture, crack propagation in the radial longitudinal (RL) plane prevailed due to the low fracture toughness in RL fracture of Mode I. In pure Mode II, propagation occurred in the RL and TL (transverse longitudinal) planes to the same extent since the toughness in RL and TL fracture is similar. Cracks were not able to propagate through the transverse adhesive joints between blocks if the bonding was good. If however the bonding was poor, interface failure occurred and cracks could propagate through the adhesive layer. (C) 2014 Elsevier Ltd. All rights reserved.
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structural limits of frp Balsa sandwich decks in bridge construction
Composites Part B-engineering, 2014Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:The span limits of two glass fiber-reinforced polymer (GFRP) bridge concepts involving GFRP-Balsa sandwich plates are discussed. The sandwich plates were either used directly as slab bridges or as decks of a hybrid sandwich-steel girder bridges. In the latter case, the potential of the sandwich decks to replace reinforced concrete (RC) decks was also evaluated. Taking the limits of manufacturing into account (800 mm slab thickness), maximum bridge spans of approximately 19 m can be reached with FRP-Balsa sandwich slab bridges, if a carbon-FRP (CFRP) arch is integrated into the Balsa core. Above this limit, hybrid sandwich-steel girder bridges can be used up to spans of 30 m. RC deck replacement requires timber and steel plate inserts into the Balsa core above the steel girders. GFRP-Balsa sandwich slabs or decks exhibit full composite action between lower and upper face sheets.
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frp Balsa composite sandwich bridge deck with complex core assembly
Journal of Composites for Construction, 2013Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:The aim of this work was to investigate to what extent the performance of a glass fiber-reinforced polymer (GFRP) sandwich slab-bridge with a uniform high-density Balsa core could be improved in terms of structural efficiency and weight by using a more complex core assembly. This core consisted of high-density and low-density Balsa and a fiber-reinforced polymer (FRP) arch inserted into the Balsa high/low density interface. Quasi-static load-bearing experiments on sandwich arch-beams with complex core assemblies under symmetric four-point and asymmetric three-point loading were performed. The FRP arch reduced the force in the upper face sheet in the mid-span region and thus prevented compression failure of the latter, which led to a higher ultimate load. It also contributed to the shear resistance by up to 20% for symmetric loading. The best overall performance in terms of structural efficiency (stiffness and resistance) and weight resulted from a core configuration with a GFRP arch between an upper high-density and lower low-density Balsa core. (C) 2013 American Society of Civil Engineers.
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shear mechanical characterization of Balsa wood as core material of composite sandwich panels
Construction and Building Materials, 2013Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:An experimental study was performed using Iosipescu specimens to evaluate the effects of parameters such as shear plane, density and adhesive joints on the shear stiffness and strength of Balsa wood panels as well as the variation of ductility with respect to the shear planes. The shear planes exerted a significant effect on shear stiffness and strength. Highest values were Obtained for the shear plane parallel to the end grain, intermediate values for the plane parallel to the flat grain and lowest values for the plane transverse to the flat grain. Shear stiffness and strength increased with increasing density of the Balsa. The thin adhesive joints in the Balsa panels between the lumber blocks increased the shear stiffness and strength with one exception. The strength of specimens with the shear plane transverse to the flat grain was reduced because of a change in the failure mode. Due to plastic deformations in the tracheids, specimens with shear planes parallel to the end grain and transverse to the flat grain exhibited significant ductility. The ductility of specimens with the shear plane parallel to the flat grain was less pronounced as it was affected by the relatively brittle lignin material of the middle lamella. (C) 2012 Elsevier Ltd. All rights reserved.
Khairul Anam - One of the best experts on this subject based on the ideXlab platform.
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Effect of Bio-based Adhesive on Tensile Strength and Bending of Balsa Wood Adhesive Joint
International Journal of Integrated Engineering, 2019Co-Authors: Moch. Syamsul Ma'arif, Resza Tania Putri, Khairul AnamAbstract:The aim of this study was to determine the effect of adhesive on tensile strength and bending strength of adhesive joints on Balsa wood by varying the type of bio-based adhesive. The use of bio-based adhesive is very potential both as a substitute for synthetic-based adhesive. In this research, adhesive joint was applied using a specimen of Balsa wood which was connected with bio-based adhesive which was varied, namely bio-based adhesive from rubber tree sap, sap of jackfruit tree and sap of breadfruit tree. In this study, tensile testing and bending testing were conducted to determine the tensile strength and bending of Balsa wood that has been connected using bio-based adhesive variations. The results of the research show that the variation of bio-based adhesive can affect the strength of the structure of Balsa wood which is done by adhesive joints because in the variation of bio-based adhesive has different adhesive characteristics so that the binding ability between bio-based adhesive surfaces is different. Fault analysis was carried out after tensile and bending tests to see the effect of bio-based adhesive variations on Balsa wood. It is evident that the results of tensile testing on rubber tree sap bio-based adhesive were 28,193 MPa, on jackfruit sap bio-based adhesive was 19,93 MPa and on breadfruit tree bio-based adhesive sap was 15,963 MPa. While the results of bending testing amounted to 23.58 MPa for bio-based adhesive rubber tree sap, on 23.45 MPa for bio-based adhesive sap and breadfruit tree sap at 19.18 MPa.
Anastasios P Vassilopoulos - One of the best experts on this subject based on the ideXlab platform.
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fracture in complex Balsa cores of fiber reinforced polymer sandwich structures
Construction and Building Materials, 2014Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:Fracture in the complex Balsa cores of fiber-reinforced polymer (FRP) sandwich beams was analyzed. The cores were composed of high- and low-density Balsa layers separated by a circular adhesive interface or FRP arch. The Balsa layers were cut from panels which consisted of Balsa blocks adhesively bonded together. Failure in the beams was initiated by cracks propagating through the Balsa core thickness. The crack locations could be predicted using the Tsai-Wu failure criterion. Cracks initiated in the lowest density blocks due to their low fracture toughness. In mixed-mode fracture, crack propagation in the radial longitudinal (RL) plane prevailed due to the low fracture toughness in RL fracture of Mode I. In pure Mode II, propagation occurred in the RL and TL (transverse longitudinal) planes to the same extent since the toughness in RL and TL fracture is similar. Cracks were not able to propagate through the transverse adhesive joints between blocks if the bonding was good. If however the bonding was poor, interface failure occurred and cracks could propagate through the adhesive layer. (C) 2014 Elsevier Ltd. All rights reserved.
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structural limits of frp Balsa sandwich decks in bridge construction
Composites Part B-engineering, 2014Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:The span limits of two glass fiber-reinforced polymer (GFRP) bridge concepts involving GFRP-Balsa sandwich plates are discussed. The sandwich plates were either used directly as slab bridges or as decks of a hybrid sandwich-steel girder bridges. In the latter case, the potential of the sandwich decks to replace reinforced concrete (RC) decks was also evaluated. Taking the limits of manufacturing into account (800 mm slab thickness), maximum bridge spans of approximately 19 m can be reached with FRP-Balsa sandwich slab bridges, if a carbon-FRP (CFRP) arch is integrated into the Balsa core. Above this limit, hybrid sandwich-steel girder bridges can be used up to spans of 30 m. RC deck replacement requires timber and steel plate inserts into the Balsa core above the steel girders. GFRP-Balsa sandwich slabs or decks exhibit full composite action between lower and upper face sheets.
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frp Balsa composite sandwich bridge deck with complex core assembly
Journal of Composites for Construction, 2013Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:The aim of this work was to investigate to what extent the performance of a glass fiber-reinforced polymer (GFRP) sandwich slab-bridge with a uniform high-density Balsa core could be improved in terms of structural efficiency and weight by using a more complex core assembly. This core consisted of high-density and low-density Balsa and a fiber-reinforced polymer (FRP) arch inserted into the Balsa high/low density interface. Quasi-static load-bearing experiments on sandwich arch-beams with complex core assemblies under symmetric four-point and asymmetric three-point loading were performed. The FRP arch reduced the force in the upper face sheet in the mid-span region and thus prevented compression failure of the latter, which led to a higher ultimate load. It also contributed to the shear resistance by up to 20% for symmetric loading. The best overall performance in terms of structural efficiency (stiffness and resistance) and weight resulted from a core configuration with a GFRP arch between an upper high-density and lower low-density Balsa core. (C) 2013 American Society of Civil Engineers.
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shear mechanical characterization of Balsa wood as core material of composite sandwich panels
Construction and Building Materials, 2013Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:An experimental study was performed using Iosipescu specimens to evaluate the effects of parameters such as shear plane, density and adhesive joints on the shear stiffness and strength of Balsa wood panels as well as the variation of ductility with respect to the shear planes. The shear planes exerted a significant effect on shear stiffness and strength. Highest values were Obtained for the shear plane parallel to the end grain, intermediate values for the plane parallel to the flat grain and lowest values for the plane transverse to the flat grain. Shear stiffness and strength increased with increasing density of the Balsa. The thin adhesive joints in the Balsa panels between the lumber blocks increased the shear stiffness and strength with one exception. The strength of specimens with the shear plane transverse to the flat grain was reduced because of a change in the failure mode. Due to plastic deformations in the tracheids, specimens with shear planes parallel to the end grain and transverse to the flat grain exhibited significant ductility. The ductility of specimens with the shear plane parallel to the flat grain was less pronounced as it was affected by the relatively brittle lignin material of the middle lamella. (C) 2012 Elsevier Ltd. All rights reserved.
Julia De Castro - One of the best experts on this subject based on the ideXlab platform.
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fracture in complex Balsa cores of fiber reinforced polymer sandwich structures
Construction and Building Materials, 2014Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:Fracture in the complex Balsa cores of fiber-reinforced polymer (FRP) sandwich beams was analyzed. The cores were composed of high- and low-density Balsa layers separated by a circular adhesive interface or FRP arch. The Balsa layers were cut from panels which consisted of Balsa blocks adhesively bonded together. Failure in the beams was initiated by cracks propagating through the Balsa core thickness. The crack locations could be predicted using the Tsai-Wu failure criterion. Cracks initiated in the lowest density blocks due to their low fracture toughness. In mixed-mode fracture, crack propagation in the radial longitudinal (RL) plane prevailed due to the low fracture toughness in RL fracture of Mode I. In pure Mode II, propagation occurred in the RL and TL (transverse longitudinal) planes to the same extent since the toughness in RL and TL fracture is similar. Cracks were not able to propagate through the transverse adhesive joints between blocks if the bonding was good. If however the bonding was poor, interface failure occurred and cracks could propagate through the adhesive layer. (C) 2014 Elsevier Ltd. All rights reserved.
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structural limits of frp Balsa sandwich decks in bridge construction
Composites Part B-engineering, 2014Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:The span limits of two glass fiber-reinforced polymer (GFRP) bridge concepts involving GFRP-Balsa sandwich plates are discussed. The sandwich plates were either used directly as slab bridges or as decks of a hybrid sandwich-steel girder bridges. In the latter case, the potential of the sandwich decks to replace reinforced concrete (RC) decks was also evaluated. Taking the limits of manufacturing into account (800 mm slab thickness), maximum bridge spans of approximately 19 m can be reached with FRP-Balsa sandwich slab bridges, if a carbon-FRP (CFRP) arch is integrated into the Balsa core. Above this limit, hybrid sandwich-steel girder bridges can be used up to spans of 30 m. RC deck replacement requires timber and steel plate inserts into the Balsa core above the steel girders. GFRP-Balsa sandwich slabs or decks exhibit full composite action between lower and upper face sheets.
-
frp Balsa composite sandwich bridge deck with complex core assembly
Journal of Composites for Construction, 2013Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:The aim of this work was to investigate to what extent the performance of a glass fiber-reinforced polymer (GFRP) sandwich slab-bridge with a uniform high-density Balsa core could be improved in terms of structural efficiency and weight by using a more complex core assembly. This core consisted of high-density and low-density Balsa and a fiber-reinforced polymer (FRP) arch inserted into the Balsa high/low density interface. Quasi-static load-bearing experiments on sandwich arch-beams with complex core assemblies under symmetric four-point and asymmetric three-point loading were performed. The FRP arch reduced the force in the upper face sheet in the mid-span region and thus prevented compression failure of the latter, which led to a higher ultimate load. It also contributed to the shear resistance by up to 20% for symmetric loading. The best overall performance in terms of structural efficiency (stiffness and resistance) and weight resulted from a core configuration with a GFRP arch between an upper high-density and lower low-density Balsa core. (C) 2013 American Society of Civil Engineers.
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shear mechanical characterization of Balsa wood as core material of composite sandwich panels
Construction and Building Materials, 2013Co-Authors: Michael Oseiantwi, Anastasios P Vassilopoulos, Julia De Castro, Thomas KellerAbstract:An experimental study was performed using Iosipescu specimens to evaluate the effects of parameters such as shear plane, density and adhesive joints on the shear stiffness and strength of Balsa wood panels as well as the variation of ductility with respect to the shear planes. The shear planes exerted a significant effect on shear stiffness and strength. Highest values were Obtained for the shear plane parallel to the end grain, intermediate values for the plane parallel to the flat grain and lowest values for the plane transverse to the flat grain. Shear stiffness and strength increased with increasing density of the Balsa. The thin adhesive joints in the Balsa panels between the lumber blocks increased the shear stiffness and strength with one exception. The strength of specimens with the shear plane transverse to the flat grain was reduced because of a change in the failure mode. Due to plastic deformations in the tracheids, specimens with shear planes parallel to the end grain and transverse to the flat grain exhibited significant ductility. The ductility of specimens with the shear plane parallel to the flat grain was less pronounced as it was affected by the relatively brittle lignin material of the middle lamella. (C) 2012 Elsevier Ltd. All rights reserved.
