Method of measuring a parameter of a composite moulding material
A method of controlling a process for the manufacture of a multicomponent sheet material having a desired pre-determined parameter comprising applying electromagnetic energy to interact with the sheet material whereby the interaction modifies the applied energy, detecting the modified energy, comparing the modified energy or data derived from it with data relating to the pre-determined parameter and modifying at least one step of the process whereby the data relating to the modified energy is modified towards the data relating to the pre-determined parameter.
1. A method of determining composite material parameters comprising fiber areal weight %, fiber volume fraction, resin areal weight % and resin volume fraction comprising:
A) a calibration step comprising:
a) providing a multimodal radiation source having a least two modes of electromagnetic energy selected from the group consisting of x-ray radiation, acoustic radiation, ultrasound radiation, light radiation, nuclear radiation, ionizing radiation, atomic radiation and/or combinations thereof;
b) providing means for measuring first and second electromagnetic energy absorption data of a composite material sample exposed to the respective first mode of electromagnetic energy followed by the second mode of electromagnetic energy;
c) cross correlating the radiation absorption data sets to determine first and second absorption parameters a 1 and a 2 :
d) conducting an analytical determination of fiber areal weight % and resin areal weight %, or fiber volume fraction and resin volume fraction, of said composite material defined as Fa and Ra, respectively:
e) correlating the first and second absorption parameters a 1 and a 2 with the determined fiber areal weight % and resin areal weight %, or fiber volume fraction and resin volume fraction, by means of a correlating function C;
B) a determination step comprising:
a) measuring further first and second electromagnetic energy absorption data of a further composite material sample;
b) cross correlating the electromagnetic energy absorption data sets to determine further first and second absorption parameters b 1 and b 2 ; and
c) calculating fiber areal weight % and resin areal weight %, or fiber volume fraction and resin volume fraction, for the further sample by application of the correlating function C to the further first and second absorption parameters b 1 and b 2 .
2. A method according to claim 1 , wherein in step (A)(e) the correlating function C is defined such that the correlated values for fiber areal weight % and resin areal weight %, or fiber volume fraction and resin volume fraction, defined as Fc and Rc are such that /Fa−Fc/<4% and /Ra−Rc/<4%.
3. A method according to claim 1 , wherein the electromagnetic energy comprises x-ray radiation.
4. A method according to claim 3 , wherein the electromagnetic energy comprises energy having a wave length ranging from 0.1×10 −9 to 10×10 −9 m (0.1 to 10 nm) and an energy between 20 keV at 100 μA to 25 keV at 120 μA.
5. A method according to claim 1 , wherein the method comprises conducting at least one step of a prepreg and/or laminate manufacturing process and measuring at least two properties of the prepreg and/or laminate before, during or after the at least one step.
6. A method according to claim 1 , wherein the method is conducted online or inline.
7. A method according to claim 6 , wherein the process is modified continuously during the process to provide in-line feedback control of the resin areal weight % and fiber areal weight %, or fiber volume fraction and resin volume fraction, of the composite material.
8. A method according to claim 7 , wherein one or more process parameters are adjusted selected from the compression of rollers, the gap between resin coater and fibrous material, the temperature of the resin and the flow rate of resin, line speed and/or a combination of the aforesaid parameters.