Composites

4 tools in the Structures area.

MIL-HDBK-17 Lamina

Statistically based lamina and laminate property data of the polymer-matrix composite systems in MIL-HDBK-17-2F (2002), the last open release of the Composite Materials Handbook data volume: carbon, glass and quartz fibers in epoxy, bismaleimide, polyimide, PEEK and cyanate-ester matrices. Pick a material to see its data-set description, summary pages and every individual data table laid out as the handbook prints them (mean, minimum, maximum, coefficient of variation, B- and A-basis values, distribution constants, specimen and batch counts, data class) for each test condition, with the normalized and as-measured columns. A signed-in analyst can turn one test condition into a lamina for the classical laminate theory tools and keep it under My Lamina, edited or as published.

MIL-HDBK-23 Core

Sandwich core and adhesive properties from MIL-HDBK-23A, Structural Sandwich Composites (1968, notices to 1974), the handbook that preceded CMH-17 Volume 6. Chapter 2 tabulates flatwise compression and plate shear of balsa, aluminum-foil, glass-fabric, asbestos, plastic-film, paper and foamed cores (average, standard deviation, proportional limit, modulus, specimen counts), the same cores at elevated temperature, heat-resistant and refractory metal honeycombs to 2,400 °F, the statistical minimum values of Table 2-6, and the elastic constants, lap-joint and peel strengths of structural adhesives. Pick a core to see every handbook row for it; a signed-in analyst can keep one row as a core for the sandwich tools, edited or as published.

Classical Laminate Theory

Classical laminate theory for a laminate built from up to four lamina (handbook data from My Lamina or typed values) in any stacking sequence, entered ply by ply or as a stacking code such as [0/±45/90]s. The tool writes the reduced stiffness of each lamina, rotates it to the laminate axes, assembles the A, B and D stiffness matrices and inverts them for the in-plane engineering constants (E_x, E_y, G_xy, ν_xy, ν_yx, shear coupling), the flexural constants (E_xf, E_yf, G_xyf, ν_xyf, ν_yxf), the through-thickness ratios ν_xz and ν_yz, and the partially inverted bending stiffness D* with its cylindrical (anticlastic curvature suppressed) and free values. Under in-plane loads, moments and a temperature change it solves for the mid-plane strains and curvatures, gives every ply's strains and stresses in the laminate and lamina axes, compares the lamina strains with the allowable strains (maximum strain criterion) and, when strengths are entered, applies the maximum stress and Tsai-Wu criteria, reports the first ply to fail with its margin of safety, the maximum and minimum fibre strains, the ply families (% 0, % ±45, % 90) and the symmetry and balance checks, and draws the stack, the through-thickness strain and stress distributions and the directional stiffness.

Sandwich Panel

Strength, stiffness and stability of a flat honeycomb or foam core sandwich panel with thin facings, by the classical sandwich theory of MIL-HDBK-23A and Allen with first-order shear deformation. The facings (from My Lamina or typed, equal or unequal) carry the membrane forces and the bending couple; the core (from My Cores, MIL-HDBK-23 data, or typed) carries the transverse shear and supports the facings. The tool writes the section properties (d, the bending stiffnesses D_x, D_y, D_xy, the shear stiffnesses U_x, U_y, the neutral axis, the weight), solves the simply supported panel under uniform pressure with the Navier series including core shear deformation (deflection with and without shear, moments, edge shear forces), adds the entered in-plane forces, moments and shear forces, and writes the margins of safety for facing tension and compression, core shear in both core directions, core crushing, facing wrinkling (honeycomb or foam formula), intracell dimpling, shear crimping and general panel buckling with shear deformation, with the equations substituted and figures of the section, the deflection and moment along the panel and the margins.

1 worked example reproduced, listed on the tool page.

Other Structures sections

Materials · Frames and Trusses · Beams · Loads and Dynamics · Joints · Stress and Strain · Stability · Plates and Shells · Thin-Walled Structures · Contact · Stress Concentrations · Fatigue · Damage Tolerance