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An analysis of the forces involved in orthogonal cutting or machining is presented in which yielding on a shear plane is assumed. The fracture toughness Gcis included and it is observed that Gcmay be determined by measuring the cutting and transverse forces together with the chip thickness for a range of cutting depths. This latter measurement enabled the shear plane angle ϕ to be determined experimentally. A simplified version of the analysis is also given in which ϕ is predicted by a cutting force minimization scheme. Neither scheme requires any details of the friction condition to be known since the transverse force is sufficient information for any type to be included in the analysis. A friction model including a coefficient of friction and an adhesion toughness is also utilized. Data for both polymer and metal cutting are taken from the literature and Gcis determined. In some datasets the tool rake angle α is also varied and the values of Gcand the yield stress σYare found to be independent of α. The force minimization method gives a good estimate of ϕ for most polymers. For metals (aluminium alloy, steel, and brass) the method worked well. For aluminium alloy Gcwas independent of α and the predicted and measured ϕ values agreed. For steel and brass this was not so. Gcwas mostly independent of α except at low values where high values of Gcwere observed. A constant value of the coefficient of friction was observed for each α value but values for both the coefficient of friction and the adhesion toughness varied significantly with increasing rake angle.

Abstract: In this paper, a unidirectional carbon-fiber composite is both experimentally and numerically investigated to study the nonlinear material behavior of impacted double cantilever beam (DCB) specimens. For the impact analysis, the load and the displacement applied from pin onto end block as well as the crack energy release rate are measured and compared with the finite element analysis results. The energy release rate is a critical measure of the resistance to crack propagation, which can be estimated by the force and displacement at the crack tip. It is found that the energy release rate measured from impact tests on the specimens is well predicted by the finite element model suggested in this study.

A number of North American vegetable and animal fat shortenings, which had been analyzed previously for their physical and textural characteristics, were analyzed also for their chemical composition. The fatty acid and triglyceride composition of the solids were calculated by analyzing the composition of the original product and the liquid phase, and by determination of the solid fat content (SFC) of the fat. The solids were also isolated by isopropanol (IP) separation, and the high melting glycerides (HMG) by acetone crystallization at 15°C. There was not much difference in total saturates andtranscontent between vegetable and animal fat shortenings. Changing formulations from soy-palm to soy-cottonseed does not change the total saturates plustranscontent. The solids of the vegetable shortenings in the ß form contained about 20% of 16:0, those in the ß' form 30% or more. The animal fat shortenings were mainly in the ß form, their solids contained 30% or more of 16:0. C54 triglyceride content of the solids of ß vegetable shortenings (calculated and IP-separated) was >45%, that of all animal fats was <25%. Solids of animal fat shortenings contain high levels of C52. The C54 triglycerides are ß-tending and should be kept low in vegetable shortening. In the HMG the C54 should not exceed 30%. This can only be achieved by incorporation of a ß' hard fat, preferably palm hard fat. Animal fat, especially lard, crystallizes in the ß form because the palmitic acid in the glyceride molecule is located in the 2-position, whereas those of vegetable fats are in the 1- and 3-position.

Fully hydrogenated soybean oil, beef fat, rapeseed oil, a rapeseed, palm and soybean oil blend, cottonseed oil and palm oil were characterized by fatty acid composition, glyceride carbon number and partial glyceride content, as well as melting and crystallization properties. The latter were established by differential scanning calorimetry. Polymorphic behavior was analyzed by X-ray diffraction of the products in the flake or granulated form and when freshly crystallized from a melt. The hard fats were dissolved in canola oil at levels of 20, 50 and 80% and crystallized from the melt. Palm oil had the lowest crystallization temperature and the lowest melting temperature; rapessed had the highest crystallization temperature and soybean the highest melting temperature. All of the hard fats crystallized initially in the =00 form. When diluted with canola oil, only palm oil was able to maintain β′ stability.

A variety of methods exist for the determination of the melting point (mp) of fats. These include the Wiley mp (AOCS Method Cc 2–38), open capillary slip point, softening point and Mettler dropping point. The conditions under which the tests are performed influence the values obtained. Several of these methods were compared using a variety of fats, including margarine and soft margarine oils, lard, butter and hydrogenated Canola oils. The Mettler dropping-point values were found to coincide with the extrapolated solid fat curves obtained using wide-line NMR for all fats except butterfat. The reproducibilities of the Mettler dropping point and softening point were excellent; that of the slip point was poor.

Abstract: Solid fat content of shortening and margarine was estimated by pulsed NMR. These values were compared with those of the melted fats using different cooling methods. Solid fat content of shortenings measured at 10 and 20 C followed the same trend as those measured on the melted fat tempered at 30 C. Solid fat content of margarines followed the same trend as those measured on the nontempered fats. Softening points of the products were similar to the dropping points of the fats, as were the temperatures of the DSC major melting peaks. Compression tests of cylindrical samples provided more information about textural characteristics of the products than one penetration tests.

Solid fat content of shortening and margarine was estimated by pulsed NMR. These values were compared with those of the melted fats using different cooling methods. Solid fat content of shortenings measured at 10 and 20 C followed the same trend as those measured on the melted fat tempered at 30 C. Solid fat content of margarines followed the same trend as those measured on the nontempered fats. Softening points of the products were similar to the dropping points of the fats, as were the temperatures of the DSC major melting peaks. Compression tests of cylindrical samples provided more information about textural characteristics of the products than one penetration tests.

A number of North American vegetable and animal fat shortenings were evaluated for their melting, crystallization, textural and polymorphic crystal characteristics and solid fat content (SFC). The majority of the dropping points and crystallization temperatures of the fats ranged from 42 to 46°C and from 27 to 31°C, respectively. Softening points of the products were higher than the dropping points of their fats, especially for the vegetable shortenings. Differential scanning calorimetry melting curves of the products were different for the various products. The animal fat shortenings were mainly in theß-polymorphic form, while vegetable shortenings containing palm oil were in theß' form. Textural evaluation was carried out on the products with the cone penetrometer, constant speed penetration and constant speed compression. Constant speed compression supplied a measure of brittleness and a degree of viscosity. Lard and shortenings containing high levels of palm oil were able to withstand large deformations without breakage. The effect of tempering temperature of the fat in the SFC determination was evaluated and the values obtained were compared with the SFC of the actual product. SFC of fat and product were determined by pulse nuclear magnetic resonance. Correlation of values within textural methods was significant (P<..01), but were not significant between texture and SFC of the fat, indicating that the nature of the crystal network also plays a role in texture.

Fully hydrogenated soybean oil, beef fat, rapeseed oil, a rapeseed, palm and soybean oil blend, cottonseed oil and palm oil were characterized by fatty acid composition, glyceride carbon number and partial glyceride content, as well as melting and crystallization properties. The latter were established by differential scanning calorimetry. Polymorphic behavior was analyzed by X-ray diffraction of the products in the flake or granulated form and when freshly crystallized from a melt. The hard fats were dissolved in canola oil at levels of 20, 50 and 80% and crystallized from the melt. Palm oil had the lowest crystallization temperature and the lowest melting temperature; rapessed had the highest crystallization temperature and soybean the highest melting temperature. All of the hard fats crystallized initially in the =00 form. When diluted with canola oil, only palm oil was able to maintain ß' stability.

This paper presents a survey of the current status of test methods for the measurement of delamination resistance of composite materials, with particular emphasis on the work performed in this area by ESIS, the European Structural Integrity Society. First, existing mode I fracture test standards are described. We then present work currently underway, both to extend the range of application of these mode I tests and to standardise mode II, mixed mode (I/II) and mode III tests. Finally, we discuss tests to characterise fatigue crack propagation.

The failure of fibre composites and adhesively bonded fibre composites under high rates of test, up to rates of about 15 m s-1 were studied in detail. The present paper. Part I of the series, considers the experimental aspects of the mode I fracture of the fibre composite materials and joints. Part II will analyse the dynamic effects which are invariably associated with high-rate tests, and will show how these effects influence the observed behaviour of the test specimens. Part III will report the results from mode II and mixed-mode I/II tests on the fibre composite materials.

A number of North American vegetable and animal fat shortenings were evaluated for their melting, crystallization, textural and polymorphic crystal characteristics and solid fat content (SFC). The majority of the dropping points and crystallization temperatures of the fats ranged from 42 to 46°C and from 27 to 31°C, respectively. Softening points of the products were higher than the dropping points of their fats, especially for the vegetable shortenings. Differential scanning calorimetry melting curves of the products were different for the various products. The animal fat shortenings were mainly in theβ-polymorphic form, while vegetable shortenings containing palm oil were in theβ′ form. Textural evaluation was carried out on the products with the cone penetrometer, constant speed penetration and constant speed compression. Constant speed compression supplied a measure of brittleness and a degree of viscosity. Lard and shortenings containing high levels of palm oil were able to withstand large deformations without breakage.

A variety of methods exist for the determination of the melting point (mp) of fats. These include the Wiley mp (AOCS Method Cc 2–38), open capillary slip point, softening point and Mettler dropping point. The conditions under which the tests are performed influence the values obtained. Several of these methods were compared using a variety of fats, including margarine and soft margarine oils, lard, butter and hydrogenated Canola oils. The Mettler dropping-point values were found to coincide with the extrapolated solid fat curves obtained using wide-line NMR for all fats except butterfat. The reproducibilities of the Mettler dropping point and softening point were excellent; that of the slip point was poor.

The failure of fibre composites under high rates of test was studied in detail, using a fracture mechanics approach to determine values of the fracture energies. The present paper, Part III of the series, considers the fracture of two different fibre composite materials under mixed-mode tensile and shear (i.e. mixed-mode I/II) and shear (i.e. mode II) loadings. Part I considered the experimental aspects of the mode I fracture of the fibre composite materials, and of adhesive joints. Part II analysed the dynamic effects which are invariably associated with high-rate tests, and showed how these effects influence the observed behaviour of the test specimens.

The dynamic effects which are commonly encountered during high-rate DCB tests with fibre composite and adhesively bonded fibre composite arms have been studied in detail. This paper, Part II of the series, follows Part I, which described the experimental aspects of the high-rate testing. Part III will report the results from mode II and mixed-mode I/II tests on the fibre-composite materials.

Abstract: A number of North American vegetable and animal fat shortenings, which had been analyzed previously for their physical and textural characteristics, were analyzed also for their chemical composition. The fatty acid and triglyceride composition of the solids were calculated by analyzing the composition of the original product and the liquid phase, and by determination of the solid fat content (SFC) of the fat. The solids were also isolated by isopropanol (IP) separation, and the high melting glycerides (HMG) by acetone crystallization at 15C. There was not much difference in total saturates andtrans content between vegetable and animal fat shortenings. Changing formulations from soy-palm to soy-cottonseed does not change the total saturates plustrans content. The solids of the vegetable shortenings in the β form contained about 20% of 16:0, those in the β′ form 30% or more. The animal fat shortenings were mainly in the β form, their solids contained 30% or more of 16:0. C54 triglyceride content of the solids of β vegetable shortenings (calculated and IP-separated) was >45%, that of all animal fats was <25%. Solids of animal fat shortenings contain high levels of C52. The C54 triglycerides are β-tending and should be kept low in vegetable shortening. In the HMG the C54 should not exceed 30%. This can only be achieved by incorporation of a β′ hard fat, preferably palm hard fat. Animal fat, especially lard, crystallizes in the β form because the palmitic acid in the glyceride molecule is located in the 2-position, whereas those of vegetable fats are in the 1- and 3-position.

Two formal chiral pool syntheses of the (−)-salicylihalamides A and B were achieved from commercially available 1,2,5,6-diacetone-d-glucose and l-rhamnose.

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