Laminated Electrothermal Heater Mat with Homogeneous Sensor Substrate
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Solution Overview
Problem
Existing electrothermal ice protection systems for aircraft and wind turbines face issues with structural weaknesses due to discontinuities at the interface between temperature sensors and dielectric layers in heater mats, leading to potential delamination and reduced fatigue strength.
Innovation Solution
A laminated electrothermal heater mat design where the temperature sensor's substrate is made of the same or compatible thermoplastic material as the dielectric layers, ensuring that the thermoplastic material disperses or fuses with the dielectric layers, eliminating discontinuities and enhancing structural strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor with polyimide film substrate is used in the heater mat, then temperature sensing function is achieved, but discontinuity is created at the interface with dielectric layers causing crack initiation and reduced structural strength
Solution Approach 1:
The substrate material of the temperature sensor is changed from polyimide film to the same thermoplastic material as the dielectric layers. This creates material homogeneity throughout the heater mat structure, eliminating the discontinuity at the interface between the substrate and dielectric layers that previously caused crack initiation and reduced structural strength.
Solution Approach 2:
The temperature sensor is constructed as a composite structure where the substrate is made of thermoplastic material that is compatible with and can be fused to the dielectric layers. This composite approach allows the sensor to maintain its sensing function while integrating seamlessly with the surrounding structural materials, preventing delamination and improving overall structural integrity.
2Reliability
If polyimide film is used as substrate for temperature sensor, then sensor encapsulation is achieved, but delamination occurs at the interface with dielectric layers reducing fatigue strength
Solution Approach 1:
Using the same thermoplastic material for both the substrate and dielectric layers creates a homogeneous structure that eliminates the interface discontinuity causing delamination. This homogeneous construction maintains sensor encapsulation while preventing the delamination that would otherwise reduce fatigue strength and service life.
Solution Approach 2:
The material parameter of the substrate is changed from polyimide film to thermoplastic material that is compatible with the dielectric layers. This parameter change enables the substrate to be fused to the dielectric layers during lamination, creating a permanent bond that prevents delamination under fatigue loading conditions and extends the service life of the heater mat.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution prevents crack initiation and de-lamination, improving the structural and fatigue strength of the heater mat, resulting in a more reliable ice protection system.
Implementation Method 1
the temperature sensor comprises a sprayed metal track deposited on a substrate comprising thermoplastic material
Implementation Method 2
the substrate is laminated to at least a first one of the dielectric layers; and the thermoplastic material of the substrate is (i) the same as the thermoplastic material of the first dielectric layer such that the thermoplastic material of the substrate is dispersed or merged into the thermoplastic material of the first dielectric layer
Implementation Method 3
an electrothermal heater mat for an ice protection system... a heater element
Data Source
AI summary
An electrothermal heater mat (3) is provided for an ice protection system for an aircraft (1) or the like. The heater mat (3) is a laminated heater mat and comprises dielectric layers (50-58), a heater element (501) and a temperature sensor (507). Each dielectric layer (50-58) comprises thermoplastic material, and the temperature sensor (507) comprises a sprayed metal track (5010, 5012) deposited on a substrate (50, 5019) comprising thermoplastic material. The substrate may be one of the dielectric layers (50) or a separate carrier (5019) which is smaller than the dielectric layers (50-58). The substrate (50, 5019) is laminated to at least a first one of the dielectric layers (53, 58) and the thermoplastic material of the substrate is (i) the same as the thermoplastic material of the first dielectric layer such that the thermoplastic material of the substrate is dispersed or merged into the thermoplastic material of the first dielectric layer or (ii) compatible with the thermoplastic material of the first dielectric layer such that the thermoplastic material of the substrate is fused to the thermoplastic material of the first dielectric layer. Thus, the formation of an undesirable discontinuity at the interface between the substrate (50, 5019) and the first dielectric layer (53, 58) is substantially prevented or minimized.