Definitions of imperfections and defects in organic matrix composite materials
BS EN 4866:2021 pdf free.Aerospace series一Definitions of imperfections and defects in organic matrix composite materials.
This document provides a list of terms with their definitions illustrated by typical photographs, in order to define a common vocabulary on the imperfections and damage that may occur during the manufacture of organic matrix composite materials (which will be called resinN in this document). Some types of damage may also be encountered in use.
This document is restricted to their definitions and does not give any acceptance criteria. The word “imperfections will be preferred to the word defect, although the word defect might be usually used. Defect acceptance criteria to be discussed between the user and customer and documented appropriately between the two parties.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• ISO Online browsing platform: available at https://www.iso.orgJobp
• IEC Electropedia: available at https://www.electropedia.org/
3.1 General
damage damage corresponds to degradation of the resin and/or the fibres caused by mechanical, thermal or environmental stresses defect imperfection or damage which exceeds the part acceptance criterion
3.1.3 imperfection particularity encountered in composite materials that may result from the manufacturing process and/or the conditions of use
Note I to entry: Detection may be carried out visually or by using laboratory equipment.
3.1.4 indication information given by non-destructive test means and which may correspond to an imperfection.
3.2 Bonding imperfections
See also EN ISO 10365.
3.2.1 absence of adhesive absence of adhesive with respect to the part definition
Note 1 to entry: See Figure B.1.
3.2.2 absence of contact presence of the required adhesive on one or both faces of the assembly, but with no contact
Note 1 to entry: Encountered in case of poor matching.
Note 2 to entry: See Figure B.2.
3.2.3 adhesive joint colour heterogeneity possible imperfections when using two-component adhesives of different colours, and caused by incomplete mixing of the components (visible in particular in the adhesive bead)
3.2.4 adhesive rupture total or partial separation of a bonding interface without rupture of neither the substrate nor the adhesive
Note 1 to entry: As opposed to cohesive rupture (characterized by a rupture within the substrate or the adhesive).
Note 2 to entry: See Figure B.3 and Figure B.4.
3.2.5 debonding separation of two items as a result of adhesive or cohesive failure in the adhesive layer
3.2.6 excessive adhesive bead localised adhesive surplus on the edge of a joint plane
3.2.7 insufficient adhesion localised insufficient adhesion between two materials (substrate, adhesive, primer, etc.) characterised by insufficient mechanical strength of the interface
3.2.8 junction imperfection incorrect positioning of one part with respect to the other during bonding
3.2.9
lack of adhesive
local lack of adhesive (insufficient quantity or poor distribution) with respect to the part definition
Note 1 to entry: See Figure B.5.
3.3 Presence of foreign substance
3.3.1 foreign object presence of any solid (non-metallic]) particle, which is not part of raw material formulation
3.3.2 inclusion metallic foreign object
Note 1 to entry: See Figure C.3 and Figure C.4.
3.3.3 pollution presence of liquid or powder substance, which is not part of raw material formulation
Note 1 to entry: See Figure C.5 and Figure C.6.
3.4 Surface imperfections
3.4.1 fern cluster of localised areas of insufficient resin on the surface, having the appearance of a fern leaf
Note 1 to entry: Fern is a special case of surface porosities.
Note 2 to entry: See Figure D.1 and Figure D.2.
3.4.2 flaking local tearing-off of material (see 3.9.8) of millimtric dimensions from the surface layer of a composite
(flake detached or not) often localised on the edge of a part or of a hole
Note 1 to entry: See Figure D.3, Figure D.4 and Figure D.5.
3.4.3 wrinkle fold of the fibres out of plane affecting one or more layers
Note 1 to entry: See Figure D.6, Figure D.7 and Figure D.8.
3.4.4 imprint hollow mark on the surface of the part related to the production tooling (mould or environment products)
Note 1 to entry: See Figure D.9.
3.4.5 indentation (dent/punching) bump of material due to an impact on the part
Note 1 to entry: See Figure D.10.
3.4.6 line flash line shaped accumulation of resin caused by an undulation close to the surface of the part
Note 1 to entry: See Figure D.11.
3.4.7 marbling heterogeneity of the part’s colour or gloss
Note 1 to entry: See Figure D.12.
3.4.8 nick cut opening onto the surface of the part, due to a mechanical action (tool), which could affect the fibres
Note 1 to entry: See Figure D.13 and Figure D.14.
3.4.9 pill cluster of fibre residues Note 1 to entry: See Figure D.15.
3.4.10 projection mark in relief (or surface topology imperfection) on the surface of the part
3.4.11 resin flash thin layer of pure resin extending over the part surface
Note 1 to entry: See Figure D.17.
3.4.12 scratch thin surface mark due to a mechanical action, affecting only the resin
Note 1 to entry: See Figure D.18.
3.4.13 surface porosities localized points of insufficient resin on the surface
Note 1 to entry: The term “crater” can be used in case of an isolated cavity opening onto the surface, of dimension greater than a few tenths of a millimetre.
Note 2 to entry: See Figure D.19 and Figure D.20.
3.5 Cavities
3.5.1 insufficient impregnation/dry area lack of impregnation of the fbres by the resin
Note 1 to entry: See Figure E.1 and Figure E.2.
3.5.2 porosities randomly distributed spherical gas cavities
Note 1 to entry: See Figure E.3, Figure E.4, Figure E.5 and Figure E.6.
3.5.3 voids cavity with a tubular shape or whatever shape, e.g bridging, piping
Note 1 to entry: Bridging is a condition where plies span an internal feature thus creating a void.
3.6 Fibres arrangement imperfection
3.6.1 bird eyes local separation of two adjacent tows
Note 1 to entry: See Figure F.1.
3.6.2 gap/ overlap ply not positioned edge to edge with respect to the adjacent ply, which generates an overlap or gap of material
Note 1 to entry: The gaps and overlaps may be in the part definition.
Note 2 to entry: See Figure F.2 and Figure F.3.
3.6.3 off-centring modification of the angle between the warp and the weft
Note 1 to entry: See Figure F.4.
3.6.4 ply misorientation deviation of the fibres’ direction in a ply (unidirectional or fabric) compared to the theoretical definition
3.6.5 resin accumulation surplus of a resin volume without fibre which could locally affect the Fibre Volume Ratio (FVR) and geometry of the part
Note 1 to entry: See Figure F.5, Figure F.6 and Figure F.7.
3.6.6 undulation waviness deformation of the fibres in or out of the plane
Note 1 to entry: See Figure F.8 and Figure F.9.
3.7 Imperfection specific to sandwiches
3.7.1 accidental filling of honeycomb cells flling of one or more honeycomb cells by skin resin, adhesive or densification resin.BS EN 4866 pdf free download.Definitions of imperfections and defects in organic matrix composite materials