Composite structures with fracture-tough matrix and methods for designing and producing the structures

A shaped article at least part of which is constituted by a composite structure comprising a matrix and a reinforcement embedded in the matrix, the reinforcement having an at least 1.5 times higher tensile strength than the matrix, the composite structure showing the following properties:

• the matrix has a compressive strength of at least 60 MPa, a modulus of elasticity of at least 40 GPa, and a fracture energy of at least 0.5 kN/m, and
• the reinforcement is in the form of plate-shaped components with
• a tensile strength of at least 300 MPa, in which case the plate-shaped components constitute at least 8% by volume of the composite structure, or
• a tensile strength of at least 500 MPa, in which case the plate-shaped components constitute at least 6% by volume of the composite structure, or
• a tensile strength of at least 700 MPa, in which case the plate-shaped components constitute at least 4% by volume of the composite structure, or
• a tensile strength of at least 1000 MPa, in which case the plate-shaped components constitute at least 3% by volume of the composite structure, or
• a tensile strength of at least 1500 MPa, in which case the plate-shaped components constitute at least 2% by volume of the composite structure, or
• a tensile strength of at least 2000 MPa, in which case the plate-shaped components constitute at least 1.5% by volume of the composite structure,
• intermediate values for the minimum volume percentage of the plate-shaped components being being calculatable by linear interpolation where both the tensile strength and the volume concentration are depicted in logarithmic scale,
• the reinforcement components being constituted by monolithic components and/or being built up of discrete subcomponents, the subcomponents being in intimate contact with each other, and/or spaced from each other and embedded in a solid embedment, the geometry of any reinforcement component which is built up of discrete subcomponents being defined by the envelope of the reinforcement component.

A shaped article at least part of which is constituted by a composite structure comprising a matrix and a reinforcement embedded in the matrix, the reinforcement having an at least 1.5 times higher tensile strength than the matrix, the composite structure showing the following properties:

• the reinforcement is in the form of large elongated reinforcement components having a transverse dimension of at least 60 mm,
• minimum requirements with respect to volume concentration of reinforcement (φ), tensile strength of the reinforcement (σa), compressive strength of the matrix (σc), and modulus of elasticity of the matrix (E) being adapted in accordance with the minimum transverse dimension (d) of the reinforcement in accordance with the following table:
• 3000 or d (mm) 60 100 250 600 1200 more φ (vol %) 1.8 1.5 1.0 0.7 0.5 0.3 σa (MPa) 190 180 150 100 75 50 σc (MPa) 55 50 40 30 20 15 E (GPa) 40 30 25 20 15 10
• intermediate values for the minimum requirements for each of the properties being calculatable by linear interpolation where both the transverse dimension (d) and the value for the property in question are depicted in logarithmic scale,
• the reinforcement components being constituted by monolithic components and/or being built up of discrete subcomponents, the subcomponents being in intimate contact with each other, and/or in a distance from each other and embedded in a solid embedment, the geometry of any reinforcement component which is built up of discrete subcomponents being defined by the envelope of the reinforcement component.

A method for predicting mechanical behaviour, and/or the effect of mechanical behaviour, of a body B of a system A including the body and subjected to a physical influence P, the mechanical behaviour including fracture of the body B or of a part of the body B as a result of the physical influence,

• the system A being complex in that
• the body B is built up as a composite body, and
• the fracture of the body B or the part thereof is complex., i.e., includes tensile fracture and fracture other than pure tensile fracture,
• the method comprising
• providing a model M of the system A, the model M including a model, designated Bmodel of the body B, or of the part thereof, the modelling including modelling based on parameters relating size and mechanical behaviour of the body B or the part thereof, the parameters including parameters related to fracture, at least one of these parameters related to fracture being a parameter which is not solely related to tensile fracture,
• performing, on the model system M, a modelling of the physical influence P,
• recording the behaviour of the model body Bmodel resulting from the influence, including the complex fracture behaviour thereof and/or the effect of said complex fracture behaviour,
• and determining the predicted mechanical behaviour of the body B or the part thereof, including the complex fracture behaviour of the body B or the part thereof, and/or the effect of the complex fracture behaviour, by transferring the recorded behaviour of the model body Bmodel to predicted behaviour of the body B or the part thereof by the use of one or more algorithms which include the above-mentioned parameters.