Effect Of Debonding Research Articles

Investigation of the solution effects on asphalt binder and mastic through molecular dynamics simulations

• Solution increased the electrostatic effect and interaction energy in asphalt binder and mastic. • The moisture damage on the asphalt-aggregate interface was the most obvious under alkaline erosion. • The moisture susceptibility of interface of mastic is lower than that of the binder. The asphalt mixture is easily affected by water erosion with different solutes. The molecular dynamics (MD) simulation method was adopted to explore the influence of solute on the nanostructure and interface interaction of both virgin/SBS asphalt binder and mastic. The changes of potential energy of asphalt solution erosion model (ASEM), as well as fractions aggregation caused by water molecules were observed. Moreover, differences on diffusion of water molecules caused by the studied solutes were explained. On this basis, the analysis of hydrogen bonds is also carried out. The results showed that saline/alkali solutes hindered the diffusion of water molecules, where water molecules in saline environment behaved the slowest diffusion rate. Meanwhile, salt maximized the hydrogen bond adsorption of water molecules on the surface of filler (silica). The mastic with a filler/binder ratio of 1.2 had the highest diffusion coefficient. From the interface perspective, an obvious interaction between calcite and solution was detected, and the salt and alkali proceeded the debonding effect of original water condition. The alkali solution led to the greatest moisture damage to the asphalt-solution-aggregate model (ASAM), followed by the saline solution. In this case, the SBS asphalt binder/mastic exhibited a higher water stability than the virgin. This study contributed to a basic reference for understanding the moisture-induced damage of asphalt mixtures under various solution conditions.

MRI compatibility of orthodontic brackets and wires: systematic review article

BackgroundBefore the magnetic resonance imaging (MRI) examination fixed orthodontic devices, such as brackets and wires, cause challenges not only for the orthodontist but also for the radiologist. Essentially, the MRI-safe scan of the fixed orthodontic tools requires a proper guideline in clinical practice. Therefore, this systematic review aimed to examine all aspects of MRI-safe scan, including artifact, thermal, and debonding effects, to identify any existing gaps in knowledge in this regard and develop an evidence-based protocol.MethodsThe Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement was used in this study. The clinical question in “PIO” format was: “Does MRI examination influence the temperature of the orthodontic devices, the size of artifacts, and the debonding force in patients who have fixed orthodontic bracket and/or wire?” The search process was carried out in PubMed, PubMed Central, Scopus, and Google Scholar databases. The search resulted in 1310 articles. After selection according to the eligibility criteria, 18 studies were analyzed by two reviewers. The risk of bias was determined using the Quality In Prognosis Studies tool.ResultsOut of the eligible 18 studies, 10 articles examined the heating effect, 6 were about the debonding effect, and 11 measured the size of artifact regarding brackets and wires. Considering the quality assessment, the overall levels of evidence were high and medium.The published studies showed that heating and debonding effects during MRI exposure were not hazardous for patients. As some wires revealed higher temperature changes, it is suggested to remove the wire or insert a spacer between the appliances and the oral mucosa. Based on the material, ceramic and plastic brackets caused no relevant artifact and were MRI-safe. Stainless steel brackets and wires resulted in susceptibility artifacts in the orofacial region and could cause distortion in the frontal lobe, orbits, and pituitary gland. The retainer wires showed no relevant artifact.ConclusionsIn conclusion, the thermal and debonding effects of the fixed orthodontic brackets and wires were irrelevant or resoluble; however, the size of the artifacts was clinically relevant and determined most significantly the feasibility of fixed brackets and wires in MRI examination.

Comparative effects of tungsten, diamond burs and laser for residual adhesive removal after orthodontic debonding on flexural strength, surface roughness and phase transformation of high-translucent zirconia: An in vitro study

ObjectivesInformation regarding the effects of orthodontic bracket debonding on zirconia restorations, and the preferred method for residual adhesive removal from the zirconia restoration surface is lacking. Thus, this study aimed to assess the effects of different methods of residual adhesive removal after orthodontic bracket debonding on flexural strength, surface roughness, and phase transformation of high-translucent (HT) zirconia. Materials and methodsThis in vitro study evaluated 72 bar-shaped HT zirconia specimens; 18 specimens were assigned to the control group. Metal brackets were bonded to the remaining specimens by resin cement. After bracket debonding, the residual adhesive on the surface of specimens was removed by three methods (n=18): a 30-flute tungsten-carbide (TC) bur at low speed, an ultrafine diamond bur at high speed, and Er:YAG laser irradiation. The surface roughness (Ra and Rz) was measured. X-ray diffraction (XRD) analysis was carried out, and the flexural strength was measured as well. Data were statistically analyzed (α=0.05). ResultsBefore polishing, all methods increased the Ra and Rz values (P<0.05) except for the diamond bur yielding a Rz value comparable to that of the control group. The Ra values of the test groups were comparable after polishing, and still higher than that of the control group (P<0.05). The flexural strength of all three test groups was comparable (P>0.05), and significantly lower than that of the control group (P<0.001). The monoclinic phase was not observed in any group. ConclusionsOrthodontic bracket debonding adversely affects the surface roughness and flexural strength of zirconia despite polishing.

Finite element analysis of the effect of longitudinal debonding on stress redistributions around fibre breaks in randomly packed fibres

One of the challenges in longitudinal strength models of unidirectional composites is to comprehensively simulate the stress redistribution around a broken fibre. This redistribution is affected by the interfacial debonding of the broken fibre from the matrix. In the present work, a novel approach using finite element modelling is developed that considers all primary contributors to the longitudinal debonding in randomly packed fibre configurations. The parametric study revealed that a larger friction coefficient, interfacial fracture toughness and interfacial shear strength shorten the debond length and increase the stress concentration factor (SCF) on the neighbouring intact fibres. The magnitude of the SCFs strongly depends on the local fibre volume fraction, the radial distance between the intact fibres and the broken fibre, and the debond length. Incorporating interfacial debonding considerably reduces the SCF overpredictions by the well-bonded models. The presence of a matrix crack, encircling the broken fibre, locally increases the SCFs in the adjacent intact fibres and marginally shortens the debond length of the broken fibre. By incorporating these results into a strength model, the influence of the longitudinal debonding and co-existing matrix cracks on failure strain of unidirectional composites can be further tuned.

Comprehensive Characterization of Furcraea selloa K. Koch Peduncle Fiber-Reinforced Polyester Composites—Effect of Fiber Length and Weight Ratio

Nowadays, scientists and researchers working on polymer composites are paying much attention to the discovery of prospective plant fibers in order to build a promising fiber-reinforced polymer composite. The present study investigated the efficacy of using a novel Furcraea selloa K. Koch peduncle fiber in reinforced composites, and the specific composite characterization was done to explore the absolute fiber length and weight ratio to accomplish superior composite properties. For that, peduncle fibers with different length-to-weight ratios were reinforced with unsaturated polyester and the corresponding composites were tested to decide the optimum fiber length-to-weight ratio for obtaining the utmost composite properties. The results indicated that the highest mechanical properties were allied with a composite reinforced with 30 mm fiber length and 30 wt.% with the tensile strength of 103.51 MPa and flexural strength of 144.65 MPa. While the remaining tested volumes showed decreased properties as compared to optimal, which might be due to debonding effects or less interfacial bonding as examined clearly in SEM images of fractured samples. Enhanced thermal stability with 390°C and relatively reduced water absorption rate was observed in the case of optimal range when compared to other testing dimensions. Moreover, the current study confirmed that FSPF composites possess promising comparable properties which would be a good alternative to existing synthetic composites.

High-Precision Probabilistic Imaging for Interface Debonding Monitoring Based on Electromechanical Impedance

Solid rocket motors (SRMs) are widely used in the aerospace and missile industries. The interface debonding between propellant/insulator/case determines the life of an SRM. Therefore, monitoring and further locating interface debonding are crucial to prevent catastrophic structural failures of an SRM. The electromechanical impedance (EMI) technique based on piezoelectric wafer transducers is a simple and sensitive structural health monitoring (SHM) method. In this study, a high-precision probabilistic imaging method of EMI for the debonding monitoring of the SRM case–insulator interface is proposed. In this method, the Gaussian window function is used to describe the variation of debonding damage index with the position. In addition, an experimental procedure based on simulated damage is presented to determine the parameter in the Gaussian window function. Finite element models of the steel case–insulator structure based on Rayleigh damping are established to analyze the effects of debonding and simulated damage on EMI signals. An experiment is conducted to verify the proposed probabilistic imaging method and the finite element analysis results. It is proved that the proposed probability method can achieve high-precision imaging of debonding of SRM case–insulator, even after several months of storage.

Asphalt mixture modification with a plastomeric compound containing recycled plastic: laboratory and field investigation

The use of recycled plastic in asphalt pavements represents a sustainable and economic choice which, if correctly designed, could significantly improve the resistance against the typical distresses of flexible pavements. For this reason, this paper aims at evaluating the mechanical properties of two asphalt mixtures modified with two plastomeric compounds through the dry method, by comparing their results with those obtained for a reference asphalt mixture modified with Styrene–Butadiene–Styrene (SBS) polymers. One of the compounds consisted of plastomeric polymers, whereas the other was made of recycled plastic and graphene. The experimental program included laboratory tests on shear gyratory compacted specimens and cores extracted from a real-scale field trial. The results showed that stiffness, fatigue and rutting resistance of the two polymeric compound modified mixtures were comparable to those of the reference mixture. Finally, a Falling Weight Deflectometer (FWD) campaign, performed in the field after one year of service life of the pavement, showed a reduced structural response of the sections constructed with compound modified mixtures with respect to the reference one because of compaction issues and possible interlayer de-bonding effects.

Back EVA recycling from c-Si photovoltaic module without damaging solar cell via laser irradiation followed by mechanical peeling.

Debonding of ethylene-vinyl acetate (EVA) copolymer is critical for recycling the end-of-life (EoL) crystalline silicon (c-Si) photovoltaic (PV) modules. The currently utilized methods are mainly based on EVA chemical dissolution or pyrolysis, which cannot recycle EVA and usually causes environmental problems. Here, a laser irradiation followed by mechanical peeling method was proposed to recycle the back EVA layer on the solar cell in the c-Si PV module. Specifically, after removing junction box, Aluminium (Al) frame and back-sheet from the c-Si module, a 1064nm optical-fiber pulsed laser was utilized to pass through the back EVA and irradiate onto the cell/EVA bonding interface. The rear Al and silver (Ag) electrodes of the solar cell would absorb the laser pulse energy to induce a temperature rise across the cell/EVA interface, which could weaken the adhesive strength of the back EVA. The dependence of the debonding effect on the power density (P) and pulse repetition rate (PRR) of the laser was investigated carefully. When the laser parameters were controlled appropriately, the back EVA layer could be mechanically peeled off easily from the solar cell, and at the same time, the peeled-off EVA and the solar cell were both undamaged by the laser treatment. The EVA recycling can reduce possible environmental pollution risk greatly. The undamaged c-Si solar cell also provides possibility to be recycled completely in subsequent processes. The recycled EVA and solar cell both have great potential for reuse. Furthermore, for PV module with defective back-sheet, the method also offers an available way to remove the EVA adhesive for replacing the back-sheet.

Experimental investigation on the effect of local debonding of longitudinal reinforcement on seismic performance of precast concrete columns

The influence of the local debonding of longitudinal reinforcement on the seismic performance of prefabricated column with the grouted longitudinal reinforcement in corrugated sleeves is investigated. A total of 10 precast concrete specimens and 1 cast-in-place concrete specimen were designed and tested. Important factors such as anchorage length, local debonding position, debonding length and axial compression ratio were considered. The seismic performance was evaluated under low cycle reversed loading tests, and the failure mode, hysteretic curve, skeleton curve, ductility performance, energy dissipation capacity and stiffness degradation of the specimens were obtained and analyzed. It is found that the hysteretic curve of the precast column with local debonded longitudinal reinforcement is fuller than that of the bonded precast column, and the ductility and energy dissipation capacity of the precast column with local debonded longitudinal reinforcements are significantly improved. The effects of the debonding length and position of the longitudinal reinforcements on the ductility, energy consumption and bending deformation of the precast columns are also discussed. This study is of great significance to improve the bearing capacity and seismic performance of prefabricated columns on the top of the independent foundation in practical engineering.

Interlayer bonding characterization of interfaces reinforced with geocomposites in field applications

Geocomposites are extensively used in asphalt pavements as they provide significant long-term pavement benefits. Indeed, when correctly installed, geocomposites enhance road pavement performance thanks to their waterproofing properties, stress absorbing membrane interlayer (SAMI) action and improved mechanical strength of the pavement. Nevertheless, the presence of an interlayer causes de-bonding effects that negatively influence the overall pavement characteristics. This paper presents an experimental investigation aimed at comparing the interlayer bonding characteristics of four different geocomposites with an unreinforced reference configuration, laid on an Italian motorway section, in which the reinforcement depth and the lower layer surface condition (milled or new) were also varied. Interlayer shear strength (ISS) was measured, on both cores and laboratory produced specimens, through Leutner and Ancona Shear Testing Research and Analysis (ASTRA) equipment. The ISS results showed that geocomposites can be successfully applied directly on milled surfaces. Moreover, the application of a normal stress, as in the ASTRA device, tends to mitigate any difference related to the specimen heterogeneity. Finally, existing laws, which correlate the results obtained with different shear equipment on unreinforced interfaces, were generalized by considering the presence of geocomposites and the corresponding ISS specification limits were proposed for both ASTRA and Leutner test.

Influence of Geocomposite Properties on the Crack Propagation and Interlayer Bonding of Asphalt Pavements.

The application of geocomposites as reinforcement in asphalt pavements is a promising solution for the maintenance/rehabilitation of existing pavements and for the construction of new pavements, whose effectiveness strongly depends on the physical and mechanical properties of the geocomposite. This study aims at assessing the influence of four different geocomposites, obtained by combining a reinforcing geosynthetic with a bituminous membrane, on the crack propagation and interlayer bonding of asphalt pavements. First, a laboratory investigation was carried out on double-layered asphalt specimens. The crack propagation resistance under static and dynamic loads was investigated through three-point bending tests (carried out on specimens with and without notch) and reflective cracking tests respectively, whereas the interlayer shear strength was evaluated through Leutner tests. Then, a trial section was constructed along an Italian motorway and a Falling Weight Deflectometer (FWD) testing campaign was carried out. The laboratory investigation highlighted that—as compared to the unreinforced system—the geocomposites increased the crack propagation energy in the layer above the reinforcement from five to ten times, indicating that they can significantly extend the service life of the pavement by delaying bottom-up and reflective cracking. However, they also worsened the interlayer bonding between the asphalt layers (de-bonding effect). The field investigation indicated that all geocomposites decreased the stiffness of the asphalt layers with respect to the unreinforced pavement as a consequence of the de-bonding effect, thus corroborating the laboratory results. Based on the results obtained, it is desirable that the geocomposite possess a high energy dissipation capability and an upper coating ensuring good adhesion between the asphalt layers. The monitoring of the existing trial section in the future will provide useful data on the long-term field performance of reinforced pavements subjected to actual motorway traffic.

Modeling Interface Debonding in Coated Fuel Particles with BISON

This work introduces a meshed debonding model intended for use with tristructural isotropic (TRISO) fuel particles. The ability to better examine the potential effects of interface debonding between the coating layers will enable a host of investigations of the stress state when complex loading and interactions between coated fuel particles are taking place. In this work, the debonding model is discussed in detail. Then, simulations are presented to show the capabilities and limitations of the model. First, a traditional high-temperature gas reactor TRISO particle is considered. Then, a TRISO particle in a graphitic matrix is analyzed, followed by a TRISO particle in a silicon carbide matrix.

Seismic response of precast bridge columns with composite non-proprietary UHPC filled ducts ABC connections

Accelerated bridge construction (ABC) utilizes advanced planning, new construction techniques and innovative detailing to expedite construction of new bridges or rehabilitation and replacement of old deteriorated bridges. ABC has been widely used in low seismic regions and mostly implemented in the superstructure elements but much less considered for substructure elements such as column-base connections, especially in moderate and high seismic regions. While robust seismic ABC connections have been developed using ultra-high performance concrete (UHPC), sole sourcing of robust commercial UHPC mixes is causing bidding issues and limiting the wide adoption of such seismic ABC connections. Thus, validating alternative solutions that use non-proprietary materials could help overcome such challenges. This paper presents experimental and analytical investigation of the structural and seismic behavior of precast bridge columns with non-proprietary UHPC-filled ducts column-to-footing connections. For this study, a recently developed non-proprietary UHPC mix at the University of Nevada, Reno (UNR) is used. Two large-scale column models, varied only in reinforcement debonding, were tested at UNR under combined axial and cyclic lateral loading to evaluate their seismic performance. The column models were compared with reference cast-in-place column models and another column model incorporating proprietary commercial UHPC-filled duct connection from previous studies. The test results showed that the column models were emulative of conventional connections. Analytical modeling for the two tested columns was also conducted and shown to successfully reproduce the local and global behaviors of column models with acceptable accuracy when bond-slip and bar debonding effects are properly considered.

Effect of different resin removal methods on enamel after metal and ceramic bracket debonding : An in vitro micro-computed tomography study.

The aim of this study was to conduct an in vitro evaluation of the effects of different adhesive debonding and polishing techniques performed after metal and ceramic bracket removal on enamel using micro-computed tomography (micro-CT). This study was performed on 42 extracted maxillary first premolars divided into 2main groups and 6subgroups as follows: metal (group1) or ceramic (group2) brackets were bonded to the teeth, then, after debonding, one of three different methods was used to remove the residual adhesive: tungsten carbide burs with pumice(A), fiber-reinforced composite burs and polishing paste(B), or Sof-Lex discs(C; 3M Dental, St Paul, MN, USA). The samples were evaluated by micro-CT before bracket bonding (T0) and after resin removal (T1). Demineralization area, demineralization depth, demineralization volume, mineral density, and mineral volume were measured. At T1, demineralization area was significantly larger in groups1A and2A compared to groups1B, 1C, 2B, and2C (P = 0.001). Group2A (ceramic bracket/tungsten carbide-pumice) had the highest demineralization volume (P = 0.001). When the groups were compared in terms of change from T0 to T1, groups1A and2A showed significantly larger changes in demineralization area compared to the other 4groups (P = 0.001). The increase in demineralization volume was larger in group2A compared to all other groups (P = 0.001). All resin removal methods damaged the enamel surface to varying degrees. Regardless of bracket type, the use of tungsten carbide and pumice should be avoided when cleaning the tooth surface after debonding. Use of composite burs and Sof-Lex discs in particular after the debonding of ceramic brackets will help minimize damage.

Preparation of photo-crosslinkable acrylic copolymer and its debonding property on silicon wafer

As silicon wafers become thinner and easier to warp, it is important to improve production efficiency of dies. In the wafer grinding and dicing process, photo-crosslinkable pressure sensitive adhesive (PSA) tapes are applied to fix the silicon wafer and greatly increase die yield. The PSA tapes must be peeled easily without any residues after UV light irradiation. Herein, a hydroxyl group containing copolymer was first synthesized from 2-ethylhexyl acrylate, methyl methacrylate, acrylic acid and hydroxyethyl acrylate monomers via free radical polymerization, followed by the introduction of methacrylate groups through the addition reaction of 2-isocyanatoethyl methacrylate with hydroxyl groups on side chain of copolymers. The photo-crosslinkable adhesive was then prepared by the mixing the copolymers with photoinitiator and aziridine crosslinker. Glass transition temperature (Tg) and storage modulus of the photo-crosslinked adhesives increased with UV irradiation time, which benefited the picking-up process. A digital microscope was used to observe the surface morphology of the debonded silicon wafers and excellent debonding effect occurred after 40 s UV irradiation.

Reusable piezo-sandwiched PTFE film for in-process monitoring of advanced composites

Environmental and cost-saving advantages derived from the use of composites attract aerospace and automotive industries as these materials offer significant structural and aerodynamic advantages over traditional metal structures. The composites industry, however, is concerned with the manufacturing processes as they cannot provide fast enough cycle time to match metal alloy processes. Our research aims to develop a sensing technology in the form of a reusable in situ cure monitoring and assessment system that can predict the formation of manufacturing defects and monitor the degree of cure. Thin-film material is chosen from various PTFE-based material by prioritizing the debonding effect and signal transmission through the composite part. Then, the film is used to sandwich piezoelectric actuators and sensors to monitor out-of-autoclave carbon fiber composite plates using ultrasonic Lamb waves by temporarily adhering to the manufactured part creating an effective electromechanical coupling between the sensing film and the laminate. Initial results, through the analysis of the fundamental antisymmetric A0 mode at low frequencies, indicate that analyzing the velocity and amplitude of these waves over cure time determines gelation and vitrification points. Experimental results have also proved the feasibility of using such a reusable film for different curing cycles, always determining certain cure parameters.

Performance of expanded polystyrene light weight self compacting concrete in composite slab

ABSTRACT Composite constructions have gained importance due to faster and economical construction. Composite sections are generally made with cold formed corrugated profile sheet, which also act as a permanent formwork. To promote the use of composite sections in construction industry, it is necessitate to target to minimize the self-weight. It also facilitates to save the construction cost. In composite slabs, shear connectors are provided for composite action. It would be difficult to pour the conventional concrete; hence self compacting concrete would be ideally suited for such places. To reach the above objective, an effort has been made to investigate the expanded polystyrene light weight self compacting concrete in composite slab. To achieve the light weight concrete, expanded polystyrene beads were added in different proportions to the coarse aggregate. The composite slab was performed for four-point bending test under flexure and push out test. The test result concluded that the light weight expanded polystyrene self compacting concrete composite slab exhibit a higher performance with reduction in the thickness of the slab. The minimum spacing of shear connector was well performed. It could able to control the shear crack and de-bonding effect between the profiled steel sheet and concrete.

Mechanisms for the control of the complex propagation behaviour of hydraulic fractures in shale

The complex propagation behaviours of hydraulic fracture (HF) at bedding planes (BPs) and the produced complicated fracture geometry are essential to enhance the production of shale gas reservoirs. To better understand the complex propagation behaviour of HF at BPs with different bond strengths, the propagation behaviour, including arrest, crossing, and deviation, was identified first from post-fracturing shale specimens. The discontinuous stress and displacement fields on both sides of a BP ahead of an HF were then determined using the numerical simulation method. Finally, three mechanisms—principal stress jump, Cook–Gordon debonding or Poisson effect, and elastic dissimilarity—were explored in detail to interpret the complex propagation behaviour. The results revealed that HF is arrested/deviated only at extremely weakly cemented or fully opened BPs, whereas HF crosses strongly cemented BPs. The high heterogeneity of the BPs in cementing strength is responsible for the complex propagation behaviour of HF. The principal stress jump at a BP is caused by the difference in stiffness between the BP and the rock matrix. The maximum tensile principal stress ahead of the HF cannot be transmitted across the weakly cemented or fully opened BPs, suggesting that the HF cannot cross BPs. The principal stresses may rotate at a weakly cemented BP, and the rotated principal stresses tend to terminate or deviate an HF. Because of Cook–Gordon debonding and the Poisson effect, if a weakly cemented BP is present and is roughly normal to an advancing HF, the BP may break at some distance ahead of the fracture tip and induce a secondary fracture along the BP. The HF then reaches the opened BP and deviates towards the BP. The propagation process of L- or T-shaped fractures can be interpreted both by the Cook–Gordon debonding and Poisson effect from the viewpoints of stress and displacement. The three mechanisms often operate together when an HF deviates towards a weak BP; while for a special case, there may be only one dominant mechanism.

The Effects of De-Bonding of Longitudinal Rebars and Its Anchoring at Center of Span on Structural Behavior of RC Beam with a Guaranteed Hinge Position under Antisymmetric Bending

The Effects of De-Bonding of Longitudinal Rebars and Its Anchoring at Center of Span on Structural Behavior of RC Beam with a Guaranteed Hinge Position under Antisymmetric Bending

Effect of Debonding on Stiffness and Long-term Creep of Sandwich panels IOP: Conference Series

The main objective of this study was to analyze the effect of debonding on the stiffness and long-term creep of sandwich panel. Sandwich panel is made of thermoplastic core which is viscoelastic in nature and debonding is the major failure mode of the sandwich panel. Sandwich beams were made of different types of materials and the different materials have different properties. Numerical modeling of sandwich beam with aluminium face sheet and polypropylene core is done. Analysis was performed by using ANSYS software and the element used in the modeling is SHELL181. Four-point load configuration was created for the model with loading of 60 % of core shear strength according to McCallum (2012) and the model were subjected to static deflection. Static deflection results were compared with experimental and theoretical results and stiffness of deboned sandwich beam was evaluated. Primary and Secondary creep was evaluated in ANSYS by using Time hardening and the Norton equations to the propylene core and Burger model was used to fit with the secondary creep of the bonded sandwich beam. The primary and the secondary creep of bonded and the deboned sandwich beams were compared and long-term creep of deboned sandwich beam was determined.