Flatwise Bending Research Articles

A high-strength laminate made of small-diameter plantation wood: Flatwise bending mechanical properties

The aim of this study was to explore the feasibility of manufacturing high-strength laminates from small-diameter plantation wood. A Chinese fir (Cunninghamia lanceolata) plantation comprising trees with a diameter at breast height of less than 30 cm was selected as the material in this study. The flatwise bending mechanical properties of the Chinese fir laminates with both non-finger-jointed (NFJ) and finger-jointed (FJ) were investigated. The results indicated that finger jointing did not affect the bending elastic modulus (MOE) of the laminates, but it could reduce the bending strength index and the coefficient of variation of the bending strength (MOR). Notably, an optimal correlation existed between the MOE and MOR for both NFJ and FJ laminates, indicating that the MOE could serve as the dominant control variable for the machine grading of laminates. The failure mode significantly influenced the bending mechanical properties of both the NFJ and FJ laminates, whose dominant failure modes were fiber failure near the knot and whole fractures of the finger jointing teeth roots, respectively. For both the NFJ and FJ laminates, the overall macroscopic morphology of the high-strength specimen was relatively flat, but the microscopic morphology was uneven owing to fiber pull out, while the low-strength specimen was the opposite. Compared to the traditional visual grading method, the proposed machine grading method could more scientifically and effectively identify the quality, reduce the coefficient of variation of the bending mechanical properties, and significantly improve the strength index of laminates. This study provides basic support for manufacturing high-strength laminates from small-diameter plantation wood.

An Evaluation of Low-Grade Red Oak and Soft Maple as Raw Material for Cross-Laminated Timber Panel Production

Abstract Utilization of hardwoods in the manufacture of cross-laminated timber (CLT) faces many challenges, one of which is the selection of raw material that is both technically and economically feasible. From an economic perspective, it would make sense to choose species and grades that are both readily available and relatively competitive with softwood species currently used in CLT manufacturing. For the purposes of this study, lower grades (2A Common, 2B Common, 3A Common, and 3B Common) of red oak and soft maple were deemed appropriate in fitting this profile. All lumber was visually graded according to both National Hardwood Lumber Association (NHLA) and Northeastern Lumber Manufacturers Association (NeLMA) grading rules, as well as nondestructively tested through flatwise bending to determine modulus of elasticity (MOE). The yield distribution of each species and NHLA grade, by visual structural grade, were analyzed. The mechanical testing of each species was analyzed based on the minimum allowable MOE of 1.2 x 106 psi as required by ANSI/PRG-320. Mechanical testing resulted in much higher yields of acceptable CLT material than visual grading, for both species. A total net worth analysis was conducted to evaluate the value of NHLA graded lumber being processed into structurally graded lumber for both species and both grading methods. Finally, a procurement analysis was conducted to determine the volume of lumber required for both species, in order to achieve a fixed volume of CLT-ready lumber.

Flexural behavior of LVL made from Australian radiata pine

As a commonly used engineering wood in modern timber constructions, laminated veneer lumber (LVL), produced from small-diameter wood, short-dimension wood, or fast-growing wood, significantly enhances material properties to meet the mechanical and physical requirements in structural engineering. This study aims to investigate the feasibility of utilizing fast-growing Australian radiata pine to produce structural LVL, providing essential theoretical support for its application in civil engineering. The investigation focuses specifically on Australian radiata pine LVL (RP-LVL) and involves a systematic experimental study to assess the bending performance of RP-LVL under various bending directions and specimen sizes. The findings reveal that the edgewise bending strength of RP-LVL is comparatively lower than its flatwise bending strength. Nevertheless, RP-LVL exhibits superior bending strength compared to conventional glulam and dimensional lumber, rendering it an attractive and suitable building material for achieving enhanced bending performance in flexure members. Moreover, the study identifies significant influences of height and width on the bending strength of RP-LVL. Consequently, prediction method is proposed to calculate the bending strength of RP-LVL, considering these size influences. Importantly, the size influences on bending strength are quantified to provide a comprehensive evaluation of the bending capacity of RP-LVL flexure members.

Mechanical characterization of visually graded boards from turkish fir and black pine by nondestructive and destructive tests

For the mechanical characterization of Turkish fir and black pine, 400 board specimens with 22 mm× 50 mm × 420 mm were visually graded according to TS 1265 standard. Nondestructive tests were here upon performed using the stress wave method. After specimens were intentionally tested under flatwise bending to research the applicability as an alternative to tension and edgewise bending tests in European strength grading system. According to analyses of variance, the mean values of MOR and MOE differed in four groups at a p<0,05 significance level for visually graded boards. High correlations were found between MOR-MOE (R2=0,837) for fir and MOR-MOE (R2=0,776) for black pine. In addition, correlations of MOR-Knot rate for fir and black pine were respectively R2=0,669 and R2=0,660 showing the effectiveness of flatwise bending tests with the visual grading standard. For nondestructive tests, the mean values of the dynamic modulus of elasticity were very close in between fir and black pine grades while the usage of defect-free density performed better than the density of the whole specimen. Higher strength classes were found for black pine boards (Class 1= C40, Class 2= C27 and Class 3= C22) compared to fir boards (Class 1= C24, Class 2= C22 and Class 3= C18), respectively. Moreover, a simplified nonlinear material model was proposed for numerical modelling, and the results were found in good agreement in terms of the bending stiffness, strength, and deformation capacity of boards especially for class 1 and class 2 in both softwood species.

Experimental Investigation on Strength and Stiffness Properties of Laminated Veneer Lumber (LVL).

This study presents a testing campaign aimed at evaluating the strength and stiffness properties of laminated veneer lumber (LVL) specimens. LVL is an engineered wood product composed of thin glued wood veneers whose use in construction for structural applications has increased due to its sustainability and enhanced mechanical performance. Despite LVL's growing popularity, there is a lack of comprehensive information regarding stress-strain responses, failure modes, and the full set of strength and stiffness properties. These are particularly essential when LVL is employed in pure timber structures or composite systems such as steel-timber or timber-concrete load-bearing elements. This research aims to bridge this knowledge gap, focusing on crossbanded LVL panels, known as LVL-C, crafted from Scandinavian spruce wood, which is an LVL product with 20% of crossbanded veneers. The study explores LVL-C mechanical behavior in three primary orthogonal directions: longitudinal, tangential, and radial. A series of mechanical tests, including compression, tension, shear, and bending, was conducted to provide a thorough assessment of the material's performance. In compression tests, different behaviors were observed in the three directions, with the longitudinal direction exhibiting the highest stiffness and strength. Tensile tests revealed unique stress-strain responses in each direction, with gradual tension failures. Shear tests showcased varying shear stress-strain patterns and failure modes, while bending tests exhibited significant strength and stiffness values in flatwise bending parallel to the grain and flatwise bending perpendicular to the grain. This paper summarizes the comprehensive testing results and discusses the obtained strength and stiffness properties of LVL-C panels, providing valuable insights into their mechanical behavior for engineering applications.

Bending and shear performance of a cross-laminated composite consisting of flattened bamboo board and Chinese fir lumber

Bamboo-wood composites are effective for utilizing the mechanical properties of bamboo and fast-growing wood resources. Investigation the application of flattened bamboo in engineering structures provides added value to bamboo resources. This paper analyzes the flatwise bending and shear properties of cross-laminated bamboo and timber (CLBT) panels consisting of flattened bamboo boards and Chinese fir lumber. A three-layer cross-laminated timber (CLT) panel made from Chinese fir lumber was used for comparison. The mechanical properties of the CLBT and CLT panels in the major strength direction were obtained through experimental tests, and theoretical and finite element models were developed to predict the panels’ bending stiffness and strength. The calculated values were compared with the experimental data. The results showed that the failure modes of the three groups of CLBT panels were similar to those of the CLT panel and were predominantly rolling shear and bonding delamination. The bending strength and modulus of the CLBT were higher than that of the CLT. Increasing the number of layers of the flattened bamboo board improved the maximum bending moment and bending stiffness of the CLBT. The bending stiffness and strength of the CLBT/CLT obtained from the finite element model were in better agreement with the static test values than the theoretical model values. The results of this study provie new information for future engineering applications and the structural design of CLBT.

Flexural Performance of Splice Connections in Cross-Laminated Timber

This study demonstrates the moment resistance performance of various splice connections of cross-laminated timber (CLT) subjected to flatwise bending. A total of 33 samples in two groups (half-lapped and single-splined) were tested under four-point bending. The influence of fastener types on the half-lapped connections was investigated. Additionally, different lap lengths were considered to understand the influence of lap length on different fastener types. Steel plates with two different thicknesses and plywoods were attached with bolts onto the bottom face only to make the single spline connections. Additionally, plywoods were attached to the CLT members in two ways: (i) with the bolt only and (ii) glue plus bolts. The effect of bolt diameters on the spline connections was also examined, and the connections were tested along both the major and minor axes. To determine the characteristic values of the resistance properties, a statistical analysis was carried out following EN 14358:2016. The results indicate the bolted lap connections experience plastic deformations, whereas the screwed lap connections exhibit relatively linear behaviour until failure. The bolted and screwed lap connection with a lap length of 100 mm showed 39% and 33% higher moment capacity, respectively, than that with a 75 mm lap length. Additionally, the rotational rigidity and ductility of the lap connections increase with the increase in lap length. Irrespective of lap lengths, the bolted lap connections show higher moment capacity, support rotation and ductility, but lower rotational rigidity than screwed lap connections. An increase in bolt diameter increases moment capacity but decreases rotational rigidity. Compared to the plywood spline connections, the steel spline connections showed approximately 24%, 5% and 73% higher moment capacity, rotational rigidity and ductility, respectively. Additionally, the plywood spline connections without glue performed better than glued connections. Overall, compared to the half-lapped connections, the single-spline connections showed better performance.

Assessment of Different Measurement Methods/Techniques in Predicting Modulus of Elasticity of Plantation Eucalyptus nitens Timber for Structural Purposes

The mechanical properties of plantation Eucalyptus Nitens timber are currently assessed by applying visual stress grading (VSG) designed for the sawn timber from the mature plantation and do not represent the actual characteristics of the resource. However, the well-known limitation of VSG application for this resource led to the discovery of other methods to grade the timber to its relevant structural grade. There is potential for hardwood plantations in Australia to supply wood to the timber industry and be used in structural applications. However, it is necessary to employ criteria to evaluate the structural properties of this resource before it could be satisfactorily used for structural purposes. This research aimed to assess the use of non-destructive technique (NDT) through acoustic wave velocity (AWV), machine stress grading (MSG), and multiple linear regression (MLR) model to predict the modulus of elasticity (MOE) as a grade-determining factor. The results showed that there was a strong correlation (R2 = 0.88) between the dynamic MOE (MOEdyn) and static MOE (MOEs) of the boards, proving the NDT as a reliable method for the MOE estimations of E. nitens timber. The results from the MLR model also showed that the density and AWV are effective parameters and their combination can be practical to estimate the MOE. There was a high correlation between the MOE obtained from MSG and MOE obtained from four-point bending, demonstrating that the MSG method through the flat-wise bending can be a suitable method for fast grading. The results also indicated that the measured MOE in the edgewise direction correlates with both the flatwise and longitudinal directions. The results also showed that the E. nitens timber resource has the potential to be used in structural applications with a wide range of MOE from 7 GPa to 21 GPa.

Assessment of Bending Strength of Afara Glued Laminated Timber using Polyurethane (PUR) Adhesive

Timber has long been a popular building material, with benefits such as low energy consumption and the ability to create an in-built atmosphere that helps to mitigate the effects of global warming. Afara (Terminalia Superba) is a well-known timber species with high demand in Nigeria. The objective of this paper is to assess the physical and mechanical properties of Afara (Terminalia Superba) wood, as well as the flexural strength in flatwise bending of its glued laminated timber beam using polyurethane (PUR) adhesive, to determine its viability for structural construction. The research specimens were made using MS758:2001, EN408, and ASTM D198:2013 standards for the physical and mechanical properties tests. By MS758:2001, a shear test for glue line integrity was conducted to assess the bond performance of the glulam. In the laboratory, bending tests were performed on five glulam beams and five solid beams. Glulam beams were glued together with polyurethane (PUR) adhesive. The bending strength of solid wood was higher than that of glue-laminated wood. Solid Afara (Terminalia Superba) beams have a bending strength of 40.09 N/mm<sup>2</sup>, whereas glued laminated timber has a bending strength of 19.18 N/mm<sup>2</sup>. The preliminary investigation of the timber under BS 5268 (structural use of timber) revealed that glue-laminated beams can be used as structural members in a flatwise orientation, despite their strength being lesser than that of solid beams. Also, the polyurethane adhesive strength has an inverse relationship with the moisture content of the specimens at room temperature.

Evaluation of Low-Grade Yellow-Poplar (Liriodendron tulipifera) as Raw Material for Cross-Laminated Timber Panel Production

Abstract Utilization of low-grade yellow-poplar (Liriodendron tulipifera) lumber would provide for alternative structural lumber sources and promote the growth of cross-laminated timber (CLT) manufacturing facilities within the Appalachian Region. A significant amount of low-grade yellow-poplar lumber (i.e., National Hardwood Lumber Association [NHLA] No. 2A and Below Grade) is utilized for wood pallets. In practice, this material is not graded for structural purposes. Additionally, research on yellow-poplar for structural use has focused on grading lumber from a small population of selected logs, not by regrading NHLA lumber from manufacturing facilities. Therefore, the research's objective was to investigate the structural grades of a typical population of NHLA graded No. 2 and lower lumber and evaluate their potential to meet structural grades necessary for CLT panels. NHLA graded lumber was regraded and assigned to visual structural grades following Northeastern Lumber Manufacturers Association rules and evaluated for flatwise bending modulus of elasticity (MOEb) by nondestructive proof loading. The results of the study indicated that 54.6 percent of the boards possessed a minimal structural visual grade required for CLT panels according to American National Standards Institutes/The Engineered Wood Association (ANSI/APA) PRG 320-2019 (2020). Splits were the most common limiting defect that downgraded boards to nonstructural grades. Also, 96.6 percent of the boards evaluated had a MOEb above the required minimal board value of 1.2 ×106 psi (8,274 MPa) listed in ANSI/APA PRG 320-2019 (2020). The results of the study indicated that a majority of NHLA low-grade yellow-poplar, when regraded for structural purposes, meets or exceeds minimum lumber grade values necessary for use in CLT panel production.

Mechanical and Physical Properties of Cross-Laminated Timber Made from Batai using Different Glue Spread Amounts

This study aimed to determine the mechanical and physical properties of the Cross-Laminated Timber (CLT) glued with different amounts of glue. Cost of glue is the outmost importance where it will help in reducing the CLT manufacturing cost. Four different amounts of glue spread were used where the glue that used was phenol-resorcinol formaldehyde (PRF);150, 200, 250 and 300g/m2. The testing of the CLT was conducted by following BS EN 408:2010, BS EN 16351:2015, ASTM D 2718 method B, ASTM D 143-94 and Japanese Agricultural Standard (JAS) 1152:2007. The analysis of physical tests that have been carried out are density, moisture content, shrinkage and swelling of the CLT’s thickness. Meanwhile, the mechanical tests were compression parallel and perpendicular to the grain, three-point bending test (flatwise and edgewise of CLT) and shear test. The highest density was shown by the CLT that using 300 g/m2 which the value was 316.41 kg/m3. Whereas the highest moisture content was shown by CLT that used 250 g/m2 with 15.49% in value. The highest thickness shrinkage percentage was 2.50%, CLT with 200g/m2 while the highest thickness swelling percentage was 5.60% which the CLT used 150 g/m2. For the flatwise bending test, it shows that the CLT that used 300 g/m2 has the highest MOE and MOR value which were 510.63N/mm2 and 8.39 N/mm2. The MOE and MOR value for edgewise bending also shows that CLT that used 300 g/m2 was the best with 1528.70 N/mm2and 13.48 N/mm2. In compression perpendicular to grain test, the CLT with 150 g/m2 shows the highest value of MOE which was 5.89 N/mm2 while CLT that used 200 g/m2 has the highest value of compressive strength with 9.10N/mm2. However, for compression parallel to grain test, the CLT that used 300 g/m2 shows the best performance with 1002.78 N/mm2 and 13.75 N/mm2 of MOE and compressive strength value. Lastly, for the shear test, the highest shear strength value was 0.39 N/mm2 which belongs to CLT that used 150 g/m2. Thus, CLT that used 300 g/m2 of glue spread amount is the best CLT which, the more the amount of glue, the better the performance of the CLT.

Performance evaluation of a novel cross-laminated timber made from flattened bamboo and wood lumber

A novel flattened bamboo-wood composite cross-laminated timber (CCLT) made from flattened bamboo and hemlock lumber was developed, and its mechanical performance was investigated and quantified in this work. The results demonstrated that the CCLT columns and control hemlock CLT counterparts had nearly equal axial compression strength, but the CCLT yielded a higher compression modulus of elasticity (MOE). Additionally, the CCLT compression behaviors were not significantly affected by the height. Compared with hemlock CLT, the CCLT exhibited a slightly higher flatwise bending MOE and strength in the major strength direction. Furthermore, the MOE and strength of the CCLT under edgewise bending were 17.3% less and 16.2% greater than those under flatwise bending, respectively. The load-carrying capacity of the CCLT was mainly governed by the interfacial failure between the bamboo and wood, in which no rolling shear failure was observed. Those features are unique for the new CCLT for engineered applications.

Characterizing engineering performance of bamboo-wood composite cross-laminated timber made from bamboo mat-curtain panel and hem-fir lumber

During the global industrialization process of manufacturing cross-laminated timber (CLT), attempts have been made to use local wood species. For areas rich in bamboo resources but relatively short in timber resources, the use of bamboo- and wood-based composites to manufacture composite CLT (CCLT) has great potential. In the present work, two new types of 3-ply CCLT panel structures constituting bamboo mat-curtain panel and hem-fir lumber were investigated. In the major and minor strength directions, flatwise bending and shear tests were conducted to investigate their failure modes, maximum bending moment, bending stiffness, modulus of elasticity (MOE), bending strength, interlaminar shear strength, and specific bending and shear performance. Moreover, 3-ply hem-fir glued-laminated timber and CLT were used as controls. The effective MOE of each panel structure was calculated according to shear analogy theory and modified gamma theory and then was compared to the measured MOE. Based on the shear analogy theory, the effect of the thickness of layers on the MOE of the panels was investigated. Results showed that unlike other types of CCLT, the new CCLT exhibited distinct plate-like orthogonal strength characteristics. Its theoretical MOE agreed well with the measured MOE as the accuracy changed with the panel structure. By changing the panel structure of the new CCLT, if the MOE of one strength direction was reduced, the MOE in the other strength direction could increase accordingly based on the layer characteristics. The results presented in this paper can provide a guidance for future design and optimization of bamboo-wood CCLT.

Preliminary evaluation of a density-based lumber grading method for hem-fir CLT manufacturing

In the manufacturing process of cross-laminated timber (CLT), lumber selection and grading are essential steps for the quality control of CLT. In this work, a density-based lumber grading method was preliminarily evaluated for hem-fir CLT manufacturing. Based on the univariate regression model of hem-fir lumber modulus of elasticity (MOE) and its density, a density-based grading model was developed. To identify the effectiveness of the model, 470 pieces of thin hem-fir lumber, were segregated into four grades: E1, E2, E3, and E4 based on their density values. Two 3-ply thin-type customized CLT panels were also fabricated with E2 grade lumber as the parallel layer and E3 grade lumber as the transverse layer. Then, five CLT beam specimens were cut from each panel for flatwise bending test. Comparing the experimental and the theoretical values of the MOE, the relative errors were found to be + 11.95% (using shear analogy theory) and − 7.21% (using gamma theory), respectively. By comparison, for this hem-fir lumber, the accuracy of this density-based grading method is close to that obtained by other means of non-destructive testing. However, it seems to be simpler and more cost-effective for the potential hem-fir CLT manufacturing in some circumstances.

Salvaged lumber for structural mass timber panels: manufacturing and testing

Portland, OR, was the first US city to implement a deconstruction ordinance in 2016. Although salvaged lumber can have a high demand, the market for small-sized lumber from deconstructed dwellings is near saturation. New applications for this material are required for market development, industry diversification, and increasing deconstruction practices. Mass timber products such as cross-laminated timber (CLT) could be a new market for this material, but presently there is minimal information qualifying the performance of mass timber panels made with salvaged lumber. Three, full-sized 3-ply experimental layups, with varying amounts of salvaged/recycled wood content, were manufactured and tested to characterize panel properties. Manufacturing processes and testing methods followed ANSI/APA PRG 320-2018; Standard for Performance Rated Cross-Laminated Timber. Each panel layup had three replicates for nine panels in total. Panels measured 1.1 m by 2.3 m by 3 plys, and test results were used to calculate the effective flatwise bending moment resistance ((FbS)eff), effective flatwise bending stiffness ((EI)eff) effective shear stiffness in flatwise bending ((GA)eff), flatwise shear resistance (Vs), percent wood failure (WF%), and percent delamination (Delamination %). Results were compared with E3 grade 3-ply CLT panels made in the United States and indicated that salvaged lumber could be used as feedstock for mass timber panels in core layers or all layers. All panel layups passed benchmarks for (FbS)eff and (EI)eff benchmarks with values greater than PRG320. Panels having salvaged lumber in core layer also met Vs benchmarks. Furthermore, all panels passed examination for WF% but struggled to meet delamination requirements. Possibilities exist for better performance if panels were made in a commercial setting. This research shows salvaged lumber has promise for manufacturing structural CLT, but more research and a larger samples size is needed to verify findings.

A comparative study on the mechanical properties of laminated veneer lumber (LVL) produced from blending various wood veneers

Rotary veneers from spotted gum (Corymbia citriodora) and white cypress pine logs (Callitris glaucophylla) recovered from the native forest in Queensland, as well as Queensland plantation hoop pine (Araucaria cunninghamii) logs were used to manufacture LVL products following six different lay-up strategies including blended species LVL. The different lay-up strategies were to determine the opportunities for improving the mechanical performance of plantation softwood LVL by including native forest veneers. The manufactured products were evaluated for their bending performance, tension, bearing strength perpendicular to the grain, and longitudinal-tangential shear strength. The all-spotted gum LVL showed superior performance in all testing compared to other construction strategies. Blending even a small amount of spotted gum veneer with plantation hoop pine veneer resulted in improved mechanical performance, especially in flatwise bending. Opportunities exist to develop more optimised construction strategies that target specific product performances while optimising the use of the variable veneer qualities generated from log processing.

Bending performance of GFRP-wood sandwich beams with lattice-web reinforcement in flatwise and sidewise directions

This paper investigates the flexural behaviors of novel composite sandwich beams that feature Paulownia or Southern pine wood core and glass fiber reinforced polymer (GFRP) face-skins reinforced with lattice-webs. A vacuum-assisted resin infusion process was employed to mold sandwich beams with different numbers of webs. Two control wooden beams and eighteen lattice-web reinforced sandwich beams were subjected to four-point bending to determine their stiffness, load capacity, and failure mechanisms in the flatwise and sidewise directions. The experimental results revealed that the composite sandwich beams in flatwise bending tests failed under a lower load but yielded a larger deflection than those in sidewise bending tests. With an increase in the number of lattice-webs, pseudo-ductility was found to increase in the flatwise directions but decrease in the sidewise directions. Analytical equations were developed for calculating the bending stiffness, load capacity, and pseudo-ductility of the GFRP-wood sandwich beams, and the corresponding analytic results were found in good agreement with the experimental results.

Degradation of a REBCO conductor due to an axial tensile stress under edgewise bending: a major stress mode of deterioration in a high field REBCO coil’s performance

The influence of an axial tensile stress under edgewise bending on the current transport property of a REBCO-coated conductor is described from the viewpoint of it being one of the major stress modes of degradation in a high field REBCO coil’s performance due to electromagnetic forces. A new type of a tensile experiment for the combination of an axial tensile stress, edgewise bending and flatwise bending on a REBCO conductor demonstrates that the combined stress increases tensile strain at the outer edge of the conductor and generates mechanical cracks in the superconducting layer, which causes an earlier degradation than a pure tensile stress. This combined stress mode can cause degradation of a high field REBCO coil’s performance below an operating hoop stress and countermeasures need to be developed.

Strain Distribution of Complex-Bending YBCO Tape in Force-Balanced Coil Applied to SMES

High-temperature superconductor power applications are still expected to be the main players in reducing carbon footprints. In superconducting magnetic energy storage, increasing the stored energy also increases the electromagnetic force, which generally requires heavier support structure. In terms of the force applied to conductors, it causes the extra bending and/or torsional strain of the REBCO tapes. To minimize the applied stress and to reduce the amount of electromagnetic force support structures, a force-balanced coil (FBC) that has a helical-like structure has been proposed. In this type of magnets, the superconducting thin tape experiences complex strains that come from flatwise and edgewise bending and tensile stress before coil operation. It is necessary to assess the applied strain distribution on the YBCO layer to fabricate an FBC. A newly developed experimental device to apply various strains to the tape and evaluate the strain distributions is presented. The results show that localized large strain will degrade the overall superconducting property.

A Novel Magnet Design Using Coated Conductor for Spiral Sector FFAG Accelerators

A superconducting coil-dominated magnet was designed for a fixed-field alternating gradient (FFAG) accelerator for carbon cancer therapy. The magnet consists of deformed pancake coils with negative bends and a saddle-shape coil with negative bends wound with coated conductors. The minimum flat-wise bending radius and the maximum edge-wise bending strain were considered when designing the coils. The field error was evaluated by using the integrated magnetic field along the beam direction and the local k + 1 value to optimize the shapes of the coils.