Nanjing, China October 31th - November 2"d

2004

Organized By College of Wood Science and Technology and the Wood-based Panel Research

Institute, Nanjing Forestry University, Nanjing, 210037, China

Sponsored By National Natural Science Foundation of China

Research Centre of Fast-growing Trees and Agro-fiber Material Engineering, Jiangsu, China

Published By Science & Techniaue Literature Press

Copyright O 2004

#@) y& "*. ;- . Nanjing Forestry University

All Rights Resewed

Editors

Xiaoyan Zhou

Changtong Mei

Juwan Jin

Xinwu Xu

Statement of Procedure

Nanjing Forestry University is the copyright holder in the compilation entitled the 7th Pacific Rim Bio-Based Composites Symposium. Nanjing Forestry University is authorized to and does grant permission to copy any paper herein with proper attribution upon request. The authors also retain their individual copyrights. Permission to copy is granted for nonprofit use.

The views expressed in this publication represent the views of the author as an individual and do not necessarily reflect the views of Nanjing Forestry University.

7 The Eyirorrmentaf Fijeradfy Woodlpo~ylactic Acid Composites V b i ~ g ' i t e Guo, Tadashi Okarno~o, Mosrifu'm Takatani and Zheng W m g .a.e....

8 The Lrlnprovement on the hterfacial Pe ce of Wood Plastic Composites X. K, rue Wu u. HuMg...-.................~.....~.,.~..*+..............~.s

New method Shape and Size Effects of Blwk Shear Test Specimen on Evaluating Bonding Strength Based on Hoffman Failure Criterion

................................................ ping yang, se~ing wong ud fi f ig ran 263

3D' Structural Panels: A Literature Review .................................................................................... J& E H~ 272

Indigenous Technologies Developed for Extraction of Oil Palm Lignocellulosic Fibres for Downstream Uses Mfahmudin Sakh , Mohd Nor Mohd Yusoff , Abdul Rahman Omar, Wan Asma

........................................................................ lbr* . p d E- 282

Nondestructive Evaluation of Ybung's Moduli of Pull-Size Wood Lmhated Composite Pole9 Cheng Piao, ToddE Shype, Chung Y: Hse and R. C. Tang .............................. 291 ~ e a s u r i n i the roughness of sanded wood surfaces . .................................... Hugh M a n s f i e , ' d - ~ ~ ~ , udia Guran andMa&Zrk

The Design and Development of Ele-nic V i i i m c t e ' He, X b n i n g and WangweiDong ...................................................... 310

Effects of A ~ e w Caul System on Strength and Stability of Snuchlral makeboard ........................................... Chmg Piao Todd E S@ Chung Hw.

Electromagnetic-shield Effectiveness of Electroconducrively Wood-based composites* Xbnmiao Liu, FengFu, & Hm ...................................................... Composite Panels from Oil Palm Ligno Celiulose Residues Koh Mok Poh, Rahim Sudin, Tan Yew Eng & M&hd Nor lMoM Yiuof............

Poster Session 1 Effect of Resin Type to the Quality of Comply Made of Wood Waste and Corrugated

cartoon M u h Yusram Massijaya,YusufSudo Hadi and Erwin Franswesti ........................ 341

2 Evalution of Varous Resin Binder Systems for OSB Panel Manufactwed from High Density Wood Species Xiang-Ming Wing, Hui Wan, Jun Shen andDanief Lefebvre ..............................

3 Thermal Transfer Properties of Low Density Wheat Strawboard zhou xkoyan, fi J M ~ , zhou ~i ngguo..........................,........................... 361

4 Properties of Strand Deck-boards for One-way Pallets Made from Used Wooden Pallets MiW& a s h i m MDski Shj& ......................................................... 367

7*, Pacific Rim Bio-Based Composites Symposium

N~ndestruetive Evaiuatisn of Young's Moduli of

Full-Size Wood Lsm~inated Composite Poles

Cl~elrg riho1, Todd F. 5hupe2, Chung Y. ~ s e ' , R C. an^^

Post-Doctoral Research Scientist, School of Renewable Natural Resources, Louisiana State University AgCenter, Baton Rouge, LA. USA. Ernail: chuiao@lsu.edu.

2~ssociate Prclfsssor, School of Renewable Natural Resources, Louisiana State University AgCenter, Baton Rouge, LA, USA. Email: tshuueQaacenter.1su.edu.

3~rinciple Wood Scientist, USDA Forest Service Southern Research Station, Pineville, LA. USA. Email: chse0fs.fed.u~

4 Professor, School of Forestry & Wildlife Sciences, Auburn University, AL. USA. Email: tangrue Qaubum.edu

ABSTRACT

An exploratory study was conducted to evaluate the Young's moduli of wood 1-ted composite poles &CP) by using a free transverse vibration method. Full-size LCP, 6.1 m long and 18.2 em in diameter, were lab-fabricated with 9 andlor 12 southern yellow pine [SW] strips of thickness, 1.9 cm, 2.9 cm and 3.8 cm. The frequency of free transverse vibration in an LCP was mwured via strain gages mounted on the pole surface &rough a StrajnSmm system. Dynamic Young's moduli evaluated by the free transverse vibration method were compared to these edculated from the measured strains and both agreed very well. The fl-ee transverse vibration method can be an alternative to the static bending method which is c o m o d y used in the evaluation of bending performance of solid wood beams and wood composite poles. Thq effect of strip-thickness on the Young's MoluG of LCP was observkd. However, a significant effect of strip-number on the Young's Moduli of LCP fabricated with 2.9-cm and 3.8-cm strips was not observed.

Keywords: Laminated composite poles (LCP), non-destructive evaluation (NDE),free transverse vibration, Young's modulus, wood utility pole

INTRODUCTION

Solid wood poles are widely used in the power transmission, distribution, and telecommunica- tion industries to cany cable lines in long distance. These wood utility poles are made of high qudity tree-fen& Icgs, which are bzcoming expensive due to the ever increasing demand for utility poles in recent years. In the 1 s t three decades, several endeavors have been made to mike full use of our renewable natural resources (e.g. Marzouk et al. 1978, Tang and Adams 1973) or to find smbsfitutes for the solid wood poles (e.g. Adams et al. 1981, Erickson 1994 and 1995). More recently, wood laminated composite poles m], which composed of

TE" Pticilic Rim Bio-Based Comgmita mpmium

&agxmid solid wood strips and bound with syn&edc resins, were developed (Piao 2003 [PhD. dis%ra~-isn]). As c o ~ i p d with campsite w d utility poles [COMPOLEl (Adams et al. 1461) and hollow v e n ~ r e d poles [HVP] m c b o n 1994), LCP are more cost-effective, easier to kbricaeci; in the she md shape to meet tlne strocturd pdomanee requirements of wood utility poles, md treat with pmqemaeives for dwal-siljq. ]Experimental and theoretical studies on the sl~lacmd behavior of LCP ingcidted &at its mwbanical properties and stiffness p e d o m c e . are eomparabfe: to those: of solid wood composite poles (Piao et al. 2004a and 2004b).

'rfibrahn methods have been extensively used for the evaluation of elastic properties of solid wood (e.g. Fukada 3950, H e m o n 1951, Kitazawa 1952, Kollman and Kerch 1960, Matsumom 1958, T a g and Hsu 1972) and wood composites (e.g. Schultz and Tsai 1968, Pu and Tang 1997, Tang and Lee 1999). As an alternative to the static methods, vibration meethods approximate the Young's modulus of wood members via xneasuring their resonant fr-equendes nsndestroctively while samples must be destructed in most static bending tests. The formula for the vibration test can be expressed as:

where p is the m a s per unit length (glcm), f, designates the resonant frequency for nth mode of vibra~on (Hz), 1 is the length of the beam (cm), I is the moment of inertia of the beam (crn4), and a, represents the eigenvdues of the frequency equation governing the flexural vibraxisns. This formula is based on the Bernoulli-Euler beam theory, which does not include the effects s f the shear dcfomaf on md rotatory inertia. When these two terms are included in the fornula, the discrepancies between vibration and defection methods are reduced (Tang and Hsu 1972).

The objective of this cumrat study is to use the free vibration method to measure the dynamic moduli of bil-size LCP, Static bending tests of the LCP specimens were also conducted for comp*son. The Youfig's ntduli of each LCP specimen were calculated from the swains yielded by the bending deflection vt~hen a smfl load was applied at the free end of K P . Shear effects were not included in the cdculation due to the fact that a large ratio of len@&ameter of the full-size LCP was imposed on the design.

MATERIAXS AND METHODS

R e prmedms used to make small-size LCP (Piao et al. 2004a) were used to fabricate N1- size K P in this study and tbey are briefly described herewith. Structural grade dimension SW (Pinus qp.) luxher with sizes of 5.08 cm (2 in.) thick x 15.36 cm (6 in.) wide x 6.1 m (20 fi) long and 5.08 crn (2 in.) thick x 20.32 cm (8 in.) wide x 6.1 m (20 ft) long was obblfied from a I d c~nsmction materids store. The rmdody selected lumber had small knots (ciianseter < I cm). The lumber was reduced to the target thickness with a planer. The size-nduced members were then cut into strips of specific target dimension by using a table saw with the saw blade adjusted to the designated angles for cutting the target trapezoid strips needed for the LCP fabrication.

7 Pacific Rim Eai~Brssd Composites Synpwium

Each ~apezoid-&hap st'rip was i n s p c d for qudity and t tose with knots were remowd. The weight md the width of the large side of each s k p we= measured, and then all strips were sacked in a room under =bient (;~~n&don for two weeks before pole fabrication. The adhesive used was the ~so~ins3-pbeuol fomaidehyde (5fle resin and comercidly obtained. Viscosity and specific gravity of WF were 800 cps and 1.177, respectively.

Strips a s i g n d to a pole fiibrica~on were rmdtrmly selected from the stacked members. Fifteen prcent of serJng agents was added to the aaesive and mixed with a blender. The adhesive was uniformly Rmd-spmd onto the two trapezoid sides of each strip in an amount d 310 &&. CCPnquendy, sonx of the excessive glue was squeezed out during the LCP fabrication when pressure was applied to each strip for binding.

The eorsscali&on of glud strips was pedomed in specially designed 6.5-m long steel molds m d each contained one top hSdf mid one boaom hdf. Glue-spread strips were formed into a pole shkpe with a IO-cnn irnside diameer, tig"191tener-l temporwily with plastic tapes and then put Into the b n o m half of tile steel mold. Thin Morn sheets were placed in between strip-formed p1m md each half of the swi mold to avoid the binding of pole surface to the inner face of the steel miid due to the sque@& out glue from the strips during fabrication An impact wen& with 48.4 kg-rn of t q u e was used to tighten the screws on both halves of the steel mold. poles were pressed in the steel molds for 36 hours at the mom temperam. They were then weighed, light sanded and stored in the same environment for 4 weeks before mechanical testing.

As abve-descri&d, basidly there were two varjiables, strip-thickness and strip- number, ineoqoi-irM in this LC@" study. Therefore, ?.he sXLD Lhichss of LCP was governed by the strip thickness which varies fmn, 1.9 crn (0.75 in), 2.9 crn (1.125 in), to 3.8 cm (1.5 in). This variable was used to evaluate the effects of shell &icbess on the sti&lesslstrength and inkgarion d WP. 'Be LCF specimens fabswtaxl for thds study were composed of either 9 or 12 trapezoid-shape strips and this variable was also used to evaluate the shape effects on the mmhar~icd propflies of LGP. Two full-size LCP specimens were fabricated for each combination s f these Wo ccecisrbles, except for the p u p s with 12 trapezoid-shape, 2.9cm thick snips, in mitkich thrw spcirrrens wxe made. Ah1 members had the same target length of 6.lm (20 fi.), except for t ihe spcimms, which had target length of 5.5 m (18 ft.). These three 5.5-rn lorig K P included me member each which bid 9 trapezoid-shape strips [i-e. 9- side LCP] with a fB~ichess of 1.9-cm and 2.9-@rn, whereas the 3d member had 12 trapezoid- shape strips [i-e. 12-side LCP] with a thickness of 1 -9-crn.

LCP spcirnens Bere nundestsuc&vefy d y n k c d f y tested by using a RIVEHLE machine in a cas,bIrver bending rilodc (Figaz I ) . Tile length of the clamped end in each LCP specimen was 61 cm. Two M-M strain gaga were bonded on Ble top a1r-l bottom sdaces 5-cm (2 in.) ;uaq from the elarrq seccen Figure 2). The s ~ c i n gages were connected to a Vishay Model 609G S@aia;Srnm System, including a Swain Gage hpur Card and a Model 6100 Scanner, which was inkrfaced witti a aicrhj-ccn~pcter. A high tensife strength nylon rope was used to a p ~ t y a load sf l8C N (40.5 Ibs) venicdly ib; the free end of each LCP specimen. Thc: nylon rope eas then cue by using a scissor^ 10 lei the LCP m e n b r vibrate freely in a bending mode (I'Igu~c 3). Tkm, the vibi-2bt;on hquencies of each spechaen were worded by a Strainsmart sufiuare. h foilows that the D y r r a ~ c Young's modulus of each LCP dong the length direction bas calcuiatcd by using Quarion I. After the dynamic test, a 220 N (49.5 lbs) load was applied to the free end of each LCP specimen by using the RnrEHLE machine for

Figure 1. LCP sprcirneos were non-datructively tested by using a RWEHLE machine.

Figure 2. Strain gages were used tu memure the wain and vibration frequencies of LCP.

7tt. Peciffc Rim Bio-Based Composites Symposium

PGESULTS AND DISCUSSION

For the ECP spximens tectd ir. tkis study, the bcredinrg vibration frequencies ranged from 3.C5 tc 3.6C IIz. The & f f e ~ r ~ c e s in ficajuencies may k amibcted to the differences in length and s h a p s of the cross xxtjon of the LGP. Figure 4 shows a typical vibration curve which was reeurdd from the dynamic bending test,

The results of static moduli and c?y,amic moduli of the %side and 12-side LCP specimens tested at 1 1 % moisture cantcnt are shown in Figures 5 and 6. As shown in these two figures, increase of Young's moduli w a s observed in both 9-side and 12-side LCP groups when its

F+ F~sciFc R l c B/o-B~& Cnmg~siies Symposium 1\

si~cU r t~ ichess was inqieasod h r n 1.9-ern to 2.9-cm but such an effect was leveled off when the shell thickness ~ t i s fmher increased &om 2.9-crn to 3.8-em. However, a significant &a of Uie s&p-nu~i~be~ on the Yowig's Moduli in both groups with 2.9cm and 3.8-cm thick strips was not observed.

Youngs Moduli of 9Side Composite Po&

i 1 / / CI Static ~ o u n g ' i - E ]

1.90 2.9 3.8

Strip Thickness (cm) I Figure 5. Corq~risonts ber?rp.-ci.e~rB a ~ r a a i c Young's rnduli ~ d c t t x l by the free transverse vibration u3cthod an0 the su~:.iEi;r Yrsuna$'s rnmuli d c u h t & Pmm the mwarement of strains in LCP members

eon~ning 9 trapezoid-shape strips.

Strip Thickness (an)

Figare 6. Campa&riara betweefi dqnadc Yoarmg's mduln' predicted by the free transverse n%ration method a& the static: Young's ardtdi a!cmlaM from the masument of strains of LCP members

containing l2 trapezoid-shape strip.

7 PsciSic P ~ T Pic-Based Cemomites Symposium .

gificcak, the dygimiic aodir::i ~f t ? ~ tcstd t@P spctimers agreed well with those calculated &om ti^, s ~ ; s i k ~~csurc_n,csnir iz t\c &tic test. T~bie 1 ilicstrates the differences between ths;sc tho YCLTI~'s r n ~ d ~ l i co;IwTA from difierent ter;.&ir,g methods. The percentage diffe~crices, Lastd or; riie \ d u e cbuhd %om the s&=otie test, are respectively, +13.7%, +9.3%, a d -C.6% for the 4-side K P grcups with the shell hiekness of 1.9-cm, 2.9-em and 3.8-cm whik values s f -2.1%, +E.8%, and +1.7% were observed, respectively, in the 12-side rnen~krs. No~ever , stael'stic&l andpsis on the cdlected data was not performed due to the fact that only a Edted number of smples was tested in this study.

TfEte 1. Fercrnhde d i 2 e r t . n ~ ~ ~ between the Young's Mdul i predicted by free transverse l g , k t k ~ d and &me calculated based on the masuremeraP of strains in a siatic test of LCP

- / E & l ; l r h l e s i i c r n ) ~ ~ ~ 1.9 2.9 3.8

I t should be noted here rjtlat in most p~viaus smdies on the elastic properties of small-size elcar wood spxii-rams, dpsinlic moduli were found to be slightly higher than those

,ed from the static =PS (e.g. Tang and Hsu 1972). However, in the test of big ;i.s;exr,bt:s like fa%1:-size pfes in &is study, many p x m e k r s which are known to have sonae influences on t,be dc~e~wiradon of their el~stic properties can not be accurately measor-9d. One of k e s e pis"5all7~ter-s was the accurate nlrasurement of the vertical distance bctbe,e~ S P ~ ~ P gages, ~ ~ ~ u n t e d 09 the S U ~ ~ C C S of k&7P shell, and the central line of the LCP sp,.ir,irri, espwisllj 3rs :hi, %side rp:ea&rs. Mbgiiir,ude and distrlhtion of moistwe content in the skcil v,d1 of &e tested LCk memkrs is mother panmeter, which may have some eEe .as on &E: C;ete1~1:4r,elion of the Young's modulus, and such an effect may be very small in t5e ksl GZ snialf clew ~ \ ; i~bh )h l ; sp i r f i~ns (e.g. Kimzawii 1952, Matsumoto 1958, Tang and Hsu JS72;. Tk~e a~ez .&e vdue of rnr;istm content of the LGP tested in this study was about 11 percent. Furtkiemcr~, th-rc neglect sf shear c&ts in the Equation 1 may have some influences on the difference &at &served ktween these two Young's Moduli (Tang and Hsu 1972). h addiei'cn, tile strains gencraleb by the bending deflection of LCP due to its body weight, b~fore &e foad was applied to its free end, must be accurately measured. After taking these parameters into account, t%c acc~racy of the dy~a&c method for the deteixnination of Young's Modulus of Iwge-size wood cemposite memklc-rs would be improved. Thus, the free ~ansberse vibtition method can be an effective and efficient alternative to the static method in the test of elastic prapefiies of large-size wood composite members.

CCbNCLUSIONS AND REMARK!3

The =tilts obtained from th is study showed that the nondestructive test using the free transverse bibration is an effective and efFieient dternatjve to the static testing method that is commonly used in the mechanical tests for the evaluation of dastic properties of large-size wood poles and beams. The elastic-pmpertyeffecting parameters, as above-mentioned, will be considered and weighted in the future tests of taper members of LCP. Furthennore, for the couectim of more reliable data on the dynanPic performance of field-installed solid wood or composite wood utility poles under weathering ccmditions, such as the windstorm and/or ice stonns, tests sf forced transverse vibration and torsional vibration, individually or combined, are highly recommended.

7' Fac6c Fim Eic-Besed Cornpos&s Symposium

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