An energy approach to the characterisation of the fracture resistance of leather / Cheng-Kung Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. XCII, N° 5 (05/1997)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. XCII, N° 5 (05/1997) . - p. 103-118 Titre : An energy approach to the characterisation of the fracture resistance of leather Type de document : texte imprimé Auteurs : Cheng-Kung Liu, Auteur ; Michael D. Mcclintick, Auteur Année de publication : 1997 Article en page(s) : p. 103-118 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The fracture resistance of chrome-tanned bovine hides was quantitatively characterized by measuring the total energy required to break the leather. This physical quantity named fracture energy is observed to more truthfully represent the fracture resistance of leather than the tensile strength or breaking elongation. Three major independent variables, moisture content, strain rate, and sampling angle were arranged according to Box Hunter's experimental design matrix, thereby deriving a second order polynomial equation. The statistical model so obtained concisely expressed the relationship between the variables and corresponding fracture resistance. The results showed that water acting as a plasticizer enhances the fracture resistance of leather. However, fracture energy started to decrease once the moisture content increased to around 90%. Contrary to its effect on tensile strength, the sampling angle has shown little effect on the fracture energy of leather. The effect of strain rates on fracture energy is not straightforward. The fracture energy at first decreases then increases with increasing strain rates. The ratio of tensile strength of Young's modulus was used to represent the toughness of leather. This parameter is dimensionless, independent of the geometric shape of the leather samples. A correlation was observed between this parameter and fracture energy. En ligne : https://drive.google.com/file/d/145d8ZUpXvdWiouUdTVcxsf2uiTzkSgjM/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7674 [article]

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Measurements of the initial strain energy of leather / Cheng-Kung Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. XCII, N° 7 (09/1997)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. XCII, N° 7 (09/1997) . - p. 157-171 Titre : Measurements of the initial strain energy of leather Type de document : texte imprimé Auteurs : Cheng-Kung Liu, Auteur ; Michael D. Mcclintick, Auteur Année de publication : 1997 Article en page(s) : p. 157-171 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : This investigation was to establish an improved method to characterize the stiffness of leather associated with its resistance to a small deformation while taking into account the nonlinear viscoelasticity of leather. Stiffness was quantitatively determined for a specimen by measuring the energy needed to stretch it to 10 percent strain. This physical quantity, called initial strain energy,was observed to be define and measure than the tensile modulus. Using Box-Hunter's experimental design method a second order polynomial equation was derived for the relationship between initial strain energy and three major independent variables: moisture content, strainrate, and sampling angle. The breaking elongation was observed to decrease as initial starin energy increase, whereas the strength did not show a direct correlation with initial strain energy alone. However, regrassion analysis provided a significant statistical relationship between tensile stength and a parametre that incorporates the effects of strain energy, moisture content and strain rate. Thus, a prediction of tensile strength may become feasible based on measurements of initial strain energy without breaking the leather. En ligne : https://drive.google.com/file/d/1rykePnBJc6PbnQ47tlKv7l7kLPlbQNLc/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7671 [article]

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Stress-relaxation behavior of leather / M. Komanowsky in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXX, N° 8 (08/1995)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXXX, N° 8 (08/1995) . - p. 243-256 Titre : Stress-relaxation behavior of leather Type de document : texte imprimé Auteurs : M. Komanowsky, Auteur ; P. H. Cooke, Auteur ; W. C. Damert, Auteur ; Paul L. Kronick, Auteur ; Michael D. Mcclintick, Auteur Année de publication : 1995 Article en page(s) : p. 243-256 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Leather exhibits a complicated mechanical behavior that can be best explained by using concepts of theoretical viscoelasticity. To permit a mathematical description of the time dependent properties of leather under different testing conditions, springs and dashpots are used. A six-element model comprised of three Maxwell units in parallel satisfactorily described stress-relaxation properties of leather. Scanning-electron micrographs reveal that fibers remain desegregated upon drying of leather in the presence of fatliquor, while stress-relaxation tests show that relaxation moduli and relaxation times decrease with increase in fatliquor content as well as with increase in temperature and moisture content. The results obtainable by the stress relation method should find application in process control, specification acceptance and service evaluation. En ligne : https://drive.google.com/file/d/1dkdbEL3N0LXOtqLxYcgp14wJEYrKJuMV/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7932 [article]

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Tearing behavior of chrome-tanned leather / Cheng-Kung Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. XCIV, N° 4 (06/1999)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. XCIV, N° 4 (06/1999) . - p. 129-145 Titre : Tearing behavior of chrome-tanned leather Type de document : texte imprimé Auteurs : Cheng-Kung Liu, Auteur ; Michael D. Mcclintick, Auteur Année de publication : 1999 Article en page(s) : p. 129-145 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Tearing tests were performed along with tensile tests on chrome-tanned leather to clarify the difference between the teraing and tensile behaviors and their fracture mechanisms. For the tearing tests, a unique zigzag fracture pattern was observed due to the fluctuations in the tearing force, whereas the tensile tests demonstrated a uniform fracture pattern. Observations also showed that strain rate does not significantly affect tearing strength, but slightly affects tensile strength. Both strengths increase with increasing moisture content until certain levels, beyond which they start to decrease with increasing moisture content. A drastic difference between these two strengths is demonstrated in their response to sampling angle change. Tearing strength showed little variation with the change of sampling angle, whereas the tensile strength was maximum when sampled parallel to the backbone, then steadily decreased when sampling angle deviated from the backbone line. Statistical analysis showed that the tensile strength did not correlate well to tearing strength, whereas a good correlation was observed between fracture energy and tearing strength. Note de contenu : - EXPERIMENTAL : Materials - Statistical modeling - Tearing and tensile tests - Measurement of the fracture energy - RESULTS AND DISCUSSION : Force-elongation curves - Regression model and analysis of variance - Strain rate - Moisture content - Sampling angle - Correlation between tearing strenght and fracture energy - Effects of staking and fatliquoring En ligne : https://drive.google.com/file/d/1zE_EOB9A_Jf0oCkOA_F6jHH_GHiq4iWX/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4456 [article]

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The use of acoustic emission in predicting the tensile strength of leather / Cheng-Kung Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. XCIV, N° 1 (01/1999)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. XCIV, N° 1 (01/1999) . - p. 8-19 Titre : The use of acoustic emission in predicting the tensile strength of leather Type de document : texte imprimé Auteurs : Cheng-Kung Liu, Auteur ; Michael D. Mcclintick, Auteur Année de publication : 1999 Article en page(s) : p. 8-19 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : This investigation is to establish a foundation for developing a nondestructive tester with an acoustic analyzer for predicting the tensile strength of leather. Observations showed an excellent correlation between the tensile strength of leather and the corresponding acoustic cumulative energy at break, read from an acoustic emission analyzer. Moreover, a linear relationship was observed between the acoustic cumulative energy at break at the initial acoustic cumulative energy when leather was stretched to 10 percent of it original length more importantly, a correlation was observed between the initial acoustic cumulative energy and the tensile strength of leather. The implication of these phenomnea is that the tensile strength of leather may be predicted without reaking the leather, by measuring the initial acoustic cumulative energy and the tensile strength of leather. The implication of these phenomena is that the tensile strength of leather may be predicted without breaking the leather, by measuring the initial acoustic cumulative energy. the result of this study thus provides an essential base facilitating the possible design of a portable leather stretcher attached with an acoustic cumulative energy. The result of this study thus provides an essential base facilitating the possible design of a portable leather stretcher attached with an acoustic sensor. This would allow the prediction of tensile strength by measuring the cumulative acoustic energy during initial stretching without breaking or damaging the leather. Note de contenu : - EXPRIMENTAL : Materials - Principle of acoustic emission - Methods and apparatus - RESULTS AND DISCUSSION : Acoustic events (hits vs time) - Amplitude distribution - Acoustic energy patterns - Acoustic cumulative energy - Relationship between tensile strength and acoustic cumulative energy - Initial cumulative energy vs acoustic cumulative energy at break - Initial cumulative energy vs tensile strength En ligne : https://drive.google.com/file/d/1ldIRjSYwmwnBdx2zotk8LkChDXRSrG0M/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4491 [article]

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