Mechanical Properties of Cashew Nut Under Compression Loading at Varied Moisture Contents
Abstract
In the present study, the moisture-dependent mechanical properties, i.e. rupture force, deformation and rupture energy along three different axes (i.e. L, B, T), of the cashew (Anacardium occidentale) varieties (Vengurle 1, Vengurle 3, Vengurle 4 and Vengurle 7) were studied at 17–85% db under compression loading. The rupture force decreases linearly (r2 ≥ 0.752) with the increase in moisture content from 17 to 85% db, for Vengurle 1 along length, width and thickness of 15,080–3467, 17,000–4275 and 21,014–3388 g; for Vengurle 3 along length, width and thickness of 25,090–4031, 26,000–3851, 31,256–3449 g; for Vengurle 4 along length, width and thickness of 22,000–3342, 21,000–3360, 27,000–3725 g; for Vengurle 7 along length, width and thickness of 20,900–5542, 25,080–5542 and 29,000–7009 g, respectively. The deformation at rupture increases linearly (r2 ≥ 0.671) with the increase in moisture content from 17 to 85% db, for Vengurle 1 along length, width and thickness of 2.1–2.98, 2.42–3.56 and 3.4–6.21 mm; for Vengurle 3 along length, width and thickness of 2.8–4.73, 2.65–4.3 and 4.21–6.16 mm; for Vengurle 4 along length, width and thickness of 4.2–6.89; 2.81–5.35 and 5.6–6.7 mm; for Vengurle 7 along length, width and thickness of 4.56–7.8, 3.2–5.56 and 6.2–7.27 mm, respectively. The rupture energy decreases linearly (r2 ≥ 0.720) with increase in moisture content from 17 to 85% db for Vengurle 1 along length, width and thickness of 143–36.58, 108–56 and 123–80.38 mJ; for Vengurle 3 along length, width and thickness of 271–59.54; 82.00–33.68 and 265–101 mJ; for Vengurle 4 along length, width and thickness of 136–80.96, 58.54–23.32 and 154–96.74 mJ; for Vengurle 7 along length, width and thickness of 273–98.26, 123–21.22 and 255–151 mJ, respectively. The rupture force was higher along thickness and decreases along width and length, and it was maximum for Vengurle 3 followed by Vengurle 7, Vengurle 4 and Vengurle 1. The deformation at rupture was higher along the thickness and decreases along width and thickness and was maximum at Vengurle 7 followed by Vengurle 4, Vengurle 3 and Vengurle 1, respectively. The rupture energy was higher at length for Vengurle 7 and decreases at Vengurle 3, followed by Vengurle 1 and Vengurle 4 along length of the cashew nut.
Effect of Moisture Content and Loading Orientation on the Mechanical Properties of Balanites Aegyptiaca Nuts
Lack of an appropriate equipment to crack balanites aegyptica nuts to obtain the kernels,
which are rich in oil and proteins, have limited their use and popularity. The manual method,
which involves cracking with stone on top of another stone or metal, is slow and risky. In
order to design appropriate processing equipment, sufficient knowledge of the mechanical
properties of the different varieties is very important. The need to get sufficient information
on the mechanical properties of balanites aegyptiaca nuts led to the study of the effect of
moisture content and loading orientation on six mechanical properties of the one end tapered
oblong and spheroidal accessions of balanites aegyptiaca (desert date) nuts. Four moisture
levels and two compressive loading orientations (axial and longitudinal) were used to test the
nuts of the two accessions in a universal-testing machine. The ranges of moisture content
used were 4.7–26.4% (d.b.) for the oblong accession and 4.7–24.2% (d.b.) for the spheroidal
accession. The six mechanical properties investigated were modulus of elasticity, bioyield
point, bioyield stress, compressive strength, rupture strength and modulus of stiffness.
Results obtained show that values of all the six properties decreased with increase in moisture
content. This inverse relationship between moisture content and the mechanical properties
investigated could be attributed to the fact that the nut of balanites aegyptiaca is spongy and
being a biological material, it becomes weaker and easier to fail as its moisture content
increases. Linear and second-order regression equations relating the six properties and
moisture content are presented. It was also found that at all the moisture levels considered,
the values of all the mechanical properties studied were higher when the nuts were loaded
longitudinally for compressive tests than when loaded axially. This means that bonds of the
nut cells are weaker to fail, and hence easier to crack when loaded axially. These findings
will be useful in the development of processing equipment for balanites aegyptiaca nuts.
The Invariance of the Vacuum is the Invariance of the World
The following theorem is demonstrated: If the vacuum is invariant under the group generated by the space integral of the time component of a local vector current, then the Hamiltonian is invariant also. A similar theorem holds for the group generated by the space integral of a space component of a local axial-vector current.