Stiffeners design parameters

Stiffener design parameters and some design considerations for stiffeners. Finally, we will examine a new concept for stiffening composite structures, namely orthogrid. 

Package design parameters such as overall size, silicon technology, ball array, ball size/pitch, heat spreader/stiffener, material selection, die/package aspect ratio, substrate material, low-fc... 

The majority of baffles are flat and as a result are very inefficient from a strength standpoint. Deflection is the governing case for flat plates loaded on one side. Tire preference is to have unstiffened baffles, and they should always be the first choice. This will be acceptable for small baffles. However, lor larger baffles, as the baffle thickness becomes excessive, stiffeners offer a more economical design. Therefore stiffeners are frequently used to stiffen the baffle to prevent the thickness of the baffle from becoming e.xces-sive. The number, size, and spacing of stiffeners are dependent on the baffle thickness. selected. There is a continual trade-off between baffle thickness and stiffener parameters. 

Procedure 5-1 Stresses in Circular Rings, 256 Procedure 5-2 Design of Partial Ring Stiffeners, 265 Procedure 5-3 Attachment Parameters, 267... 

The design in Fig. 8.33c is an improvement on the concepts illustrated in Fig. 8.336. Here the bottom cross leg has been removed. That permits the upper portions to become nominal wall thickness (A). The inside radii (C3) have been increased to equal the nominal wall thickness, which is the ideal configuration. The outside radii are the inside radii plus a wall thickness (E = C3 + A). A stiffening rib has been added at the center of the part. Its height should not exceed the nominal wall thickness (H < A). Its thickness (J) should be designed using the same parameters as elsewhere where there are material build-ups (D = 1.25A). If the rib is greater than described by this equation, a sink will appear where there is a dashed line. This can be masked by... 

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