Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1998 A study to ascertain the viability of ultrasonic nondestructive testing to determine the mechanical characteristics of wood/agricultural hardboards with soybean based adhesives Charles Raymond Colen Jr. Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Agriculture Commons, Industrial Engineering Commons, Materials Science and Engineering Commons, and the Wood Science and Pulp, Paper Technology Commons Recommended Citation Colen, Charles Raymond Jr., "A study to ascertain the viability of ultrasonic nondestructive testing to determine the mechanical characteristics of wood/agricultural hardboards with soybean based adhesives " (1998). 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All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 11 Graduate College Iowa State University This is to certify that the Doctoral dissertation of Charles Raymond Colen Jr. has met the dissertation requirements of Iowa State University Signature was redacted for privacy. a^t^r Professor Signature was redacted for privacy. For the Major Program Signature was redacted for privacy. For the Graduate Program iii THii' mctyyuAy^crCpt d^edyicated/ to- yyiy lovwo^ ^a^vidpcM'evxty iw heoA/ew: Mr. cvnd/Mry. U.S. Coiew, Sr. a^nd/ Ehier a^nd/Mry. O.hJ. Sr. I CMw etervuiUy ^atefub tcr tKe^ /bt^ CvvdA^/idAxah^'. WCthouX: their fbrtctudei icicrOfLce/ Oywd/ ^UAjdav\xx/, th(4^ edAA^ccctioricd/ achCe\/em£^ wcnddy lootr hoA/e bee^v pcryidhle. Eve^o/ though/ they ewe y\xyt here to- celehratexuithme/U^hody, I wiZicelebrate\viXh/them/ivi'my SKKd/. WCthdU/m^ lo^/ea^nd/reapect, I dedX<:ateth(4'dC&iertatUyvvto-them/. ChcwleyR. Coieriijr. IV TABLE OF CONTENTS LIST OF TABLES vi LIST OF FIGURES vii ABSTRACT viii CHAPTER I. INTRODUCTION 1 Problem of the Study 3 Purpose of the Study 3 Need for the Study 4 Research Questions 4 Statistical Hypotheses 5 Assumptions of the Study 5 Limitations of the Study 5 Procedures of the Study 6 Definition of Terms 7 CHAPTER 2. REVIEW OF LITERATURE 10 Historical Overview of Ultrasonic Nondestructive Testing 11 Nondestructive Testing of Wood and Wood Composites 16 CHAPTER 3. METHODOLOGY 21 Population of the Study 21 Sample of the Study 21 Level of Confidence 22 Experimental Design 22 Variables 23 Instrumentation 25 Destructive test 25 Nondestructive test 25 Data Collection 29 Nondestructive procedure 29 Destructive procedure 32 Analysis 33 Summar>- 34 CHAPTER 4. RESULTS AND FINDINGS 35 Restatement of the Purpose 35 Experimental Results 39 Findings Related to the Hypotheses 40 V Findings Related to the Research Questions 42 Summarv' 48 CHAPTERS. CONCLUSIONS 50 Summary 50 Recommendations 52 Future Research 53 APPENDIX A. FREQUENCY SPECTRUM AND FREQUENCY RANGES FOR 55 VARIOUS APPLICATIONS OF ULTRASONIC TESTING APPENDIX B. RAW DATA OF DESTRUCTIVE MOE VALUES AND TIME OF 56 FLIGHT MEASUREMENTS FROM NON DESTRUCTIVE TESTS APPENDIX C. CALCULATION OF NONDESTRUCTIVE MOE VALUES FROM 58 TIME OF FLIGHT DATA FOR WOOD/AGRICULTURAL HARDBOARDS REFERENCES 62 ACKNOWLEDGEMENTS 66 VI LIST OF TABLES Table 3.1. Sample content of wood/agricultural hardboards 24 Table 4.1. Results of the nondestructive test MOE and destructive test MOE 36 Table 4.2. Correlation analysis for the destructive MOE vs. nondestructive MOE 41 Table 4.3. Results of the ANOVA procedure for the test of Hgip, = 0 vs ^ 0 43 vii LIST OF FIGURES Figure 3.1. DesUoictive 3-point test 26 Figure 3.2. Nondestructive test instrumentation 27 Figure 3.3. Four modules of post test replay analysis 28 Figure 3.4. Wood-agricultural hardboard sample (9" x 9" x i/g") marks for placement 30 of the transducers Figure 3.5. Location of transducers for ultrasonic nondestructive test 31 Figure 3.6. Destructive test hardboard cutting layout 33 Figure 4.1. Normal probability plots of the destructive test MOE 45 Figure 4.2. Residuals plot of NDT 45 Figure 4.3. Residuals plot of the fitted data 46 Figure 4.4. The data when NDT values are placed into the linear model 47 Figure 4.5. The regression line with 95% CI and 95% PI bands 48 viii ABSTRACT There have been numerous studies with ultrasonic nondestructive testing and wood fiber composites. The problem of the study was to ascertain whether ultrasonic nondestructive testing can be used in place of destructive testing to obtain the modulus of elasticity (MOE) of the wood/agricultural material with comparable results. The uniqueness of this research is that it addressed the type of content (constalks and switchgrass) being used with the wood fibers and the type of adhesives (soybean-based) associated wdth the production of these composite materials. Two research questions were addressed in the study. The major objective was to determine if one can predict the destructive test MOE value based on the nondestructive test MOE value. The population of the study was wood/agricultural fiberboards made from wood fibers, cornstalks, and switchgrass bonded together with soybean-based, urea-formaldehyde, and phenol-formaldehyde adhesives. Correlational analysis was used to determine if there was a relationship between the two tests. Regression analysis was performed to determine a prediction equation for the destructive test MOE value. Data were collected on both procedures using ultrasonic nondestructing testing and 3-point destructive testing. The results produced a simple linear regression model for this study which was adequate in the prediction of destructive MOE values if the nondestructive MOE value is known. An approximation very close to the entire error in the model equation was explained from the destructive test MOE values for the composites. The nondestructive MOE values ix used to produce a linear regression model explained 83% of the variability in the destructive test MOE values. The study also showed that, for the particular destructive test values obtained with the equipment used, the model associated with the study is as good as it could be due to the variability in the results from the destructive tests. In this study, an ultrasonic signal was used to determine the MOE values on nondestructive tests. Future research studies could use the same or other hardboards to examine how the resins affect the ultrasonic signal. 1 CHAPTER I. INTRODUCTION The desired possibility of examining materials without destroying them using ultrasonics originated in the late 1920s and early 1930s in Germany by Mulhauser, Trost. and Pohlman. and at the same time in Russia by Sokoloff. all of whom investigated various continuous wave techniques (Green. Jr.. 1991). Developments since the 1930s have made ultrasonics one of the most