Composite material stiffness coefficient nondestructive measurement method

A technology of composite materials and measurement methods, which is applied in the direction of measuring devices, analyzing materials, and using sound waves/ultrasonic waves/infrasonic waves for material analysis, etc. It can solve problems such as inaccurate measurement results, debonding of piezoelectric sheets, and increased complexity.

Pending Publication Date: 2017-05-31
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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Problems solved by technology

At present, most researchers use the method of pasting piezoelectric sheets (or piezoelectric sheet arrays) on the surface of the test piece to excite or receive Lamb waves. This contact detection method may cause debonding of piezoelectric sheets during the service of composite materials. , the change of sensor-structure coupling conditions will lead to inaccurate measurement results or experimental failu

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  • Composite material stiffness coefficient nondestructive measurement method
  • Composite material stiffness coefficient nondestructive measurement method
  • Composite material stiffness coefficient nondestructive measurement method

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Embodiment Construction

[0050] The flow chart of the non-destructive measurement method of the composite material stiffness coefficient proposed by the present invention is shown in figure 1 , including the following steps:

[0051] The first step is to model the positive problem theory:

[0052] First, it is assumed that the guided wave displacement field distribution in the composite layup is

[0053]

[0054] The coordinates x and y are the in-plane directions, and z is along the plate thickness direction; u, v and w are the displacement components in the x, y and z directions respectively; the displacement field has 12 unknown quantities, respectively u 0 , ψ x , v 0 , ψ y ,w 0 , ψ z ,φ x , χ x , φ y , χ y , φ z , χ z . The above formula represents a typical third-order plate theoretical displacement field function. Considering the stress-free boundary conditions on the upper and lower surfaces of the plate when Lamb waves propagate in the plate

[0055]

[0056] The subscrip...

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Abstract

The invention discloses a composite material stiffness coefficient non-destructive recognition method based on an ultrasonic Lamb wave technology. The method comprises the four parts including direct problem theoretical modeling, sensitivity analysis, measurement of phase velocity value by experiments and stiffness coefficient inverse problem solving; for a direct problem theoretical model, the self derived novel third-order plate theory is used for solving the spread theoretical phase velocity value of Lamb waves in a composite material plate; the theory considers the plate wave stress free boundary conditions; the complicated step of shearing correction factor calculation required by the ordinary plate theory is avoided; for the sensitivity analysis, the proper spreading angle and the Lamb wave mode are selected, and are the premise for complete reconstruction of nine stiffness coefficients; the experiment uses a non-contact type laser ultrasonic system, and an advanced signal processing method is combined, so that the multi-angle waveguide phase velocity value measurement is completed; finally, an intelligent optimization algorithm is combined; the optimal solution of the composite material stiffness coefficient is obtained through the minimum experimental measurement phase velocity value and the theoretical calculation phase velocity value.

Description

Technical field: [0001] The invention designs a non-contact method for measuring mechanical performance parameters of composite materials, and in particular relates to a non-destructive measurement method for stiffness coefficient of composite materials, which belongs to the technical field of performance evaluation of composite materials. Background technique: [0002] Carbon fiber composite materials are widely used in aerospace, automobile and shipbuilding industries due to their high specific strength, specific stiffness and corrosion resistance. However, the mechanical property analysis and structural design of composite materials must be based on sufficient and accurate performance data. At the same time, in the process of composite material processing and production, it is also necessary to evaluate the mechanical properties of the composite material to strictly monitor the implementation of the processing technology and prevent the existence of defects such as compos...

Claims

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Application Information

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IPC IPC(8): G01N29/04G01N29/44
CPCG01N29/046G01N29/44G01N2291/023Y02T90/00
Inventor 裘进浩赵金玲季宏丽
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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