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Pendahuluan Material Komposit
BAB 2 Macromechanical Analysis of a Lamina Angle Lamina Stress-Strain Qomarul Hadi, ST,MT Teknik Mesin Universitas Sriwijaya Sumber Bacaan Mechanics of Composite Materials by Kaw
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Hooke's Law for a 2D Angle Lamina
Gambar 2.20 Local and global axes of an angle lamina
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Relationship of Global and Local Stresses
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Relationship of Global and Local Strains
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Expanding Global Strain-Local Strain Relationship
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Global Stress and Strain
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Transformed Compliance Matrix
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Transformed Reduced Stiffness Matrix
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Pendahuluan Material Komposit
BAB 2 Macromechanical Analysis of a Lamina Engineering Constants Qomarul Hadi, ST,MT Teknik Mesin Universitas Sriwijaya Sumber Bacaan Mechanics of Composite Materials by Kaw
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Pure Axial Load in Direction x
Gambar 2.23 Application of stresses to find engineering constants of an angle lamina
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Engineering Constants
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Pure Axial Load in Direction y
(b) Gambar 2.23 Application of stresses to find engineering constants of an angle lamina
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Engineering Constants
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Pure Shear Load in x-y Plane
(c) Gambar 2.23 Application of stresses to find engineering constants of an angle lamina
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Engineering Constants
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Stress-Strain Relationships for Angle Lamina
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Engineering Constant Ex of an Angle Lamina
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Engineering Constant Ey of an Angle Lamina
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Engineering Constant Gxy of an Angle Lamina
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Engineering Constant mx of an Angle Lamina
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Engineering Constant my of an Angle Lamina
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Pendahuluan Material Komposit
BAB 2 Macromechanical Analysis of a Lamina Invariant Form of Transformed Matrices Qomarul Hadi, ST,MT Teknik Mesin Universitas Sriwijaya Sumber Bacaan Mechanics of Composite Materials by Kaw
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Invariant Form of Stiffness Matrix
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Invariant Form of Compliance Matrix
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Pendahuluan Material Komposit
BAB 2 Macromechanical Analysis of a Lamina Maximum Stress Failure Theory Qomarul Hadi, ST,MT Teknik Mesin Universitas Sriwijaya Sumber Bacaan Mechanics of Composite Materials by Kaw
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Strength Failure Theories for an Angle Lamina
The failure theories are generally based on the normal and shear strengths of a unidirectional lamina. In the case of a unidirectional lamina, the five strength parameters are: Longitudinal tensile strength Longitudinal compressive strength Transverse tensile strength Transverse compressive strength In-plane shear strength
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Maximum Stress Failure Theory
The lamina is considered to be failed if: is violated. Note that all five strength parameters are positive numbers. Each component of stress does not interact with each other.
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Example Find the maximum value of S>0 if a stress of
is applied to a 60o lamina of Graphite/Epoxy. Use Maximum Stress failure theory. Use properties of a unidirectional Graphite/Epoxy lamina given in Table 2.1 of the textbook Mechanics of Composite Materials by Autar Kaw. Gambar 2.33 Off-axis loading in the x-direction
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Solution The stresses in the local axes are
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Solution The ultimate strengths of a unidirectional Graphite/Epoxy lamina are:
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Solution Then using the inequalities of the Maximum Stress Failure Theory: or, All the inequality conditions (and )are satisfied if The above inequalities also show that the angle lamina will fail in shear. The maximum stress that can be applied before failure is:
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