The electronic pdf versions of the documents found through http://www.dnv.com/ are the officially binding versions. Copyright Det Norske Veritas.

[Book] [Expand] [Collapse] [Search Forms] [Previous Section with Hits] [Next Section with Hits] [Clear Search] [Help]

Expand Search

B: Joints [Table of Contents] D: Interfaces

DNV-OS-C501 Composite Components

[-] Sec.7: Joints and Interfaces
[-] C: Specific joints

Sec.7
C. Specific joints

Sec.7
C 100   Laminated joints

Sec.7 C
101   Laminated joints rely on the strength of the interface for load transfer. The interface has resin dominated strength properties. Defects in the interface tend to be more critical than defects in the interface of plies of laminate, because the joint interface is the only and critical load path.

Sec.7 C
102   The strength of the joint may be different from the through thickness matrix properties of the laminate, because the joint may be a resin rich layer and the joint may be applied to an already cured surface instead of a wet on wet connection. (see manufacturing). The strength of the joint should be documented.

Sec.7 C
103   Laminated joints are very sensitive to peel conditions. Peel stresses should be avoided.

Sec.7 C
104   For the interface between the joining laminates the matrix design rules given in section 5 apply. The resistance of the interface shall be determined with the same level of confidence as specified in section 4 A600. It shall be recognised that the resistance of the interface between the laminates may not be the same as the corresponding resistance parameter of the joining laminates. Resin rich layers may even have to be analysed by different failure criteria, e.g., the yield criterion in section 6 F.

Sec.7 C
105   The laminates themselves, including possible over-laminations, shall be analysed like regular laminates.

Sec.7
C 200   Adhesive Joints

Sec.7 C
201   All issues related to laminated joints also apply to adhesive joints.

Sec.7 C
202   Geometrical details should be clearly specified, especially at points of stress concentrations like the edges of the joints.

Sec.7 C
203   The relationship between all elastic constants of both substrates and the adhesive should be carefully considered. Mismatches may introduce stresses or strains that can cause failure of the joint.

Sec.7 C
204   Thermal stresses should be considered.

Sec.7 C
205   Long term performance of adhesive should be established with great care. The long term performance is not only influenced by properties of the substrate, the adhesive and the interface, but also by the surface preparation and application method.

Sec.7 C
206   Relevant long term data shall be established exactly for the combination of materials, geometry, surface preparation and fabrication procedures used in the joint.

Sec.7 C
207   An adhesive joint may also introduce local through thickness stresses in the composite laminate that can lead to failure inside the laminate in the joint region.

Sec.7
C 300   Mechanical joints

Sec.7 C
301   Mechanical joints are often very sensitive to geometrical tolerances.

Sec.7 C
302   Creep of the materials shall be considered.

Sec.7 C
303   The pretension of bolted connections shall be chosen by considering possible creep of the material under the bolt.

Sec.7 C
304   It is preferred to design the joint in a way that its performance is independent of the matrix. This way matrix cracking or degradation of matrix properties are not important for the performance of the joint.

Sec.7
C 400   Joints in sandwich structures

Sec.7 C
401   All aspects related to laminated, adhesive and mechanical joint apply also to sandwich structures.

Sec.7 C
402   Sandwich structures have internal joints between core and skin and between cores. These joints are usually evaluated independently, but their properties are treated as an internal part of the sandwich system. Often the core properties are modified to incorporate the joint properties.

Sec.7 C
403   When two sandwich structures are joined complicated stress fields may result inside the sandwich structure. Stresses inside the core can be very different near a joint compared to the typical shear stresses in a panel.

Sec.7 C
404   A large sandwich plate can be well described by core shear properties obtained from large test specimens. In the neighbourhood of joints local variations in properties of the core may become critical.
B: Joints [Table of Contents] D: Interfaces