Methods for characterizing, distinguishing and measuring contact areas

Abstract

To provide a method that obtains thermal properties of a contact region.SOLUTION: A method of the present application comprises: receiving temperature data on a sensor; obtaining a temperature distribution of heat penetration from the sensor into at least one material; applying a correction to the temperature distribution; iteratively analyzing the corrected temperature distribution; and outputting thermal properties of a contact region being a region between the sensor and the at least one material. The method of the present application may further comprise: obtaining thermal properties of at least one material; and obtaining a corrected thermal property of a material using the thermal property of the contact region. The method of the present application may further comprise automatically obtaining appropriate measurement duration for measuring properties of the at least one material to minimize effects of the contact region.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to thermal property measurements, and more particularly to thermal property measurements of contact areas between materials in contact with one another. [Background technology]

[0002] Materials in contact with each other can be analyzed for their thermal properties, such as surface thermal effusivity and bulk material thermal effusivity. When analyzing the thermal properties of materials in contact, physical contact between the materials is not taken into account. Typically, a combination of bulk and surface material properties is measured without distinguishing between surface or contact properties and bulk material properties. However, physical contact between these two or more materials in contact can affect the thermal properties of the materials being analyzed. For example, porosity, heterogeneity, and / or surface imperfections in one or more materials can significantly alter the thermal properties of the materials.

[0003] Therefore, a method for characterizing, differentiating, and measuring the thermal properties of contact between materials is desirable. Summary of the Invention

[0004] According to one aspect of the present disclosure, a method is disclosed that includes receiving temperature data from a sensor, determining a temperature distribution of heat ingress from the sensor into at least one material, applying a correction to the temperature distribution, repeatedly analyzing the corrected temperature distribution, and outputting thermal characteristics of a contact area, which is a region between the sensor and the at least one material.

[0005] In the method, the temperature data may be the temperature of the sensor over time.

[0006] In the method, the contact area may include the sensor and may be an area between two of the at least one material.

[0007] In the method, the repeated analysis may be a non-linear fitting analysis.

[0008] The method may further comprise determining a thermal property of the at least one material and determining a corrected thermal property of the at least one material using the thermal property of the contact area.

[0009] The method may further comprise automatically determining an appropriate measurement period for measuring the at least one material property to minimize the effect of the contact area.

[0010] The method may include determining a thermal property of the thin film, the thin film being between the sensor and the at least one material.

[0011] According to another aspect of the present disclosure, a method is disclosed that includes receiving temperature data from a sensor, determining a temperature distribution of heat ingress from the sensor into two or more materials, applying a correction to the temperature distribution, determining thermal properties of a contact area between the two or more materials, and outputting the thermal properties of the contact area.

[0012] In the method, the temperature data may be the temperature of the sensor over time.

[0013] In the method, the sensor may be provided within the contact area.

[0014] The method may further comprise iteratively analyzing the corrected temperature distribution before determining the thermal properties of the contact area, wherein the iterative analysis may comprise performing a non-linear fitting analysis.

[0015] The method may further comprise determining thermal properties of the two or more materials and determining corrected thermal properties of the two or more materials using the thermal properties of the contact area.

[0016] The method may further comprise automatically determining an appropriate measurement period for measuring the properties of the two or more materials to minimize the effect of the contact area.

[0017] The method can include determining a thermal property of the at least one thin film between the sensor and at least one of the two or more materials.

[0018] According to another aspect of the present disclosure, there is provided a method comprising: placing a sensor at a contact area between a first material and a second material; heating the sensor for a predetermined time; determining a temperature distribution of heat ingress from the sensor into the first material or the second material; repeatedly analyzing the temperature distribution; and determining thermal properties of the contact area, which is a region between the first material and the second material.

[0019] The method may further comprise applying a correction to the temperature distribution before repeatedly analyzing the temperature distribution.

[0020] The method may further comprise determining thermal properties of the first material and the second material, and determining corrected thermal properties of the first material and the second material using the thermal properties of the contact area.

[0021] The method may further comprise automatically determining an appropriate measurement period for measuring the properties of the first material and the second material to minimize the effect of the contact area.

[0022] The method can include determining a thermal property of the at least one thin film between the sensor and at least one of the first material and the second material. [Brief explanation of the drawings]

[0023] Further features and advantages of the present disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0024] [Figure 1] FIG. 1 is a diagram showing a thermal contact model.

[0025] [Figure 2] FIG. 2 shows an embodiment of a thermal contact model using a thin film.

[0026] [Figure 3] FIG. 3 shows an embodiment of the thermal contact model using a layered system.

[0027] [Figure 4] FIG. 4 illustrates an embodiment of an asymmetric thermal contact model.

[0028] [Figure 5] FIG. 5 is a graph showing temperature measurements for the thermal contact model using extruded polystyrene.

[0029] [Figure 6] FIG. 6 is a graph showing temperature measurements for a thermal contact model using rough expanded polystyrene.

[0030] [Figure 7] FIG. 7 is a graph showing temperature measurements for a thermal contact model using cut expanded polystyrene.

[0031] [Figure 8] FIG. 8 is a graph showing temperature measurements from 0 to 10 seconds for the thermal contact model using stainless steel 304.

[0032] [Figure 9] FIG. 9 is a graph showing temperature measurements from 0 to 0.5 seconds for the thermal contact model using polished stainless steel 304.

[0033] In addition, like reference numerals are used to designate like parts throughout the accompanying drawings.

[0034] [Detailed explanation] Disclosed herein are methods and models for determining thermal properties of a contact area. The method includes receiving temperature data from a sensor and determining a temperature distribution of heat penetration from the sensor into at least one material. A correction term is then applied to the temperature distribution to determine a corrected temperature distribution. The corrected temperature distribution is repeatedly analyzed to output a thermal property of at least one contact area. The contact area may be an area between two materials. The contact area includes an area between the sensor and the at least one material.

[0035] A method for determining the thermal properties of the contact area between two materials can be applied using a thermal contact model, which can also be thought of as a method for determining the contact properties between the surfaces of each material. Thermal contact models are described in more detail below.

[0036] As mentioned above, when analyzing the thermal properties of materials in contact with each other, physical contact between the materials is not taken into account. However, physical contact between these two or more contacting materials can affect the thermal properties of the materials being analyzed. In particular, porosity, heterogeneity, and / or surface imperfections in one or more of the materials can affect the thermal properties of the materials being analyzed. The methods and models described herein can be used for experimental measurements of a variety of materials and surfaces. Both surface or contact thermal properties (e.g., thermal effusivity) and bulk material thermal properties can be extracted from planar heat source measurements of thermal properties.

[0037] The methods and models described herein can be used to characterize, differentiate, and measure thermal contact and surface thermal effusivity between materials to calculate and measure the thermal properties of each contacting material or object. The methods described herein are derived from thermal waves. It is understood that heat reflection provides a useful method for modeling heat transport across material interfaces. When a thermal wave encounters an interface between two materials, it is reflected and transmitted. The reflection and transmission coefficients and properties of a temperature wave (with temperature as amplitude) traveling from a first material to a second material can be used to determine the time evolution of any temperature distribution, for example, by the method of images. This is at least in part because a temperature distribution can be decomposed into a set of temperature waves, and the reflection and transmission coefficients for the temperature wave at the interface of two materials are frequency independent.

[0038] FIG. 1 illustrates a thermal contact model 100. This thermal contact model is a one-dimensional model that can be used to characterize the effects of imperfect contact between materials, for example, on the transient planar heat source method. The thermal contact model 100 includes a first material 102 and a second material 104. Both materials 102 and 104 can be the same bulk sample material with a thermal effusivity b2 and a diffusivity α2. However, each of the materials 102 and 104 can be different materials with different thermal effusivities and diffusivities, as described in more detail below. A sensor 106 is positioned at the contact area 108 between the materials 102 and 104. The sensor 106 can be a planar sensor embedded or sandwiched in the center of the contact area 108 between the two materials 102 and 104. The sensor 106 can be a heat source that is heated with a constant power for a predetermined period of time.

[0039] The contact area 108 can be a thin area with a width of 2L and a thermal effusivity of b1. The contact area 108 can be thought of as a thin barrier separating the materials 102 and 104, corresponding to the surfaces of the contacting materials 102 and 104. This approximation allows the contact area 108 between the sensor 106 and the materials 102 and 104 to be treated as a single homogeneous layer.

[0040] Although model 100 represents contact area 108 as a single homogeneous layer, it can be more accurately described as a series of layers with different thermal properties. The single-layer approximation holds true only if the layers are sufficiently thin and after a sufficiently long heating time. Multilayer interfaces can introduce frequency-dependent reflections due to interference, but this has little effect on the low-frequency components of the heating process, which can dominate heat transfer after a short time for a constant-power heat source.

[0041] For calculations and measurements using the thermal contact model 100, the sensor 106 or heating element is positioned at x=0 to create a symmetrical situation. Materials 102, 104 are introduced in the x direction with |x|>L.

[0042] As discussed above and in more detail below, the thermal contact model 100 can be used to measure and calculate various thermal properties of the contact area 108 and materials 102, 104. The temperature distribution in the model 100 can then be calculated or determined using an image method using reflection coefficients. In some embodiments, the width 2L of the contact area 108 is unknown. Without a way to directly measure L, the diffusivity of the contact area 108 cannot be easily obtained. Instead, the equation for the temperature of the sensor 106 can be defined by a time constant, such as:

number

number

[0043] In the present invention, the time constant described above can be used to automatically determine the measurement period (time window) of data to be considered in the conventional method. This measurement period represents the period during which the contact offset is constant. Data during this measurement period is considered valid data for determining thermal properties in the conventional property determination method. This valid data can be considered as data when the effect of contact between materials on the thermal properties of the materials is minimal.

[0044] Also, the time constant t L can be used to derive the contact thermal conductance coefficient H and the heat capacity per unit area ξ of the contact region 108 between the side of the sensor 106 and the material 104. The contact thermal conductance coefficient H is the inverse of the contact thermal resistance.

[0045] It should be noted that although the above derivation is based on a one-dimensional model 100, this derivation can also be used to obtain approximate correction terms for higher-dimensional models, such as a flat disk heat source, over a sufficiently short test time. This correction term accounts for the effects of contact between materials and the effects of the sensor itself. L ) is greater than (i.e. t>>t L ), the temperature at the sensor can be such that the contact correction reaches a certain offset before higher-dimensional effects become significant.

number

[0046] Furthermore, t>>t L If heat transfer in the contact model 100 remains predominantly one-dimensional until

number

number

[0047] T mdl A correction term (Tc(t)) can be applied to a transient plane heat source model (3D model) with a temperature rise of (t). The corrected form of this model can be obtained using Equation 4:

number

[0048] For the disk-shaped heat source and isotropic sample, T mdl (t) can be expressed as Equation 5.

number

[0049] The thermal contact model 100 described above can be used to determine the thermal properties of the contact area 108 or the surfaces of the materials 102, 104. This may be done by iteratively analyzing Equation 4 above. The iterative analysis may be a nonlinear fitting analysis. This iterative analysis may be used to isolate the thermal properties of the contact area 108. A computer is used to perform this iterative analysis accurately and efficiently. The computer performs the iterative analysis of the data automatically, efficiently, and accurately. Note that a nonlinear fitting analysis is also performed on the one-dimensional model of each equation.

[0050] Determining the thermal properties of the contact area 108 allows for a more accurate determination of the thermal properties of the materials 102, 104. This is done because, as discussed above, conventional methods do not consider the effect of the contact area or surface of each material when modeling a transient planar heat source. The present method uses correction terms for the model 100 to account for the effect of contact between the materials. The thermal properties of the contact area that are determined include, but are not limited to, contact thermal conductance, the inverse of the contact thermal resistance of the contact area, and heat capacity per unit area.

[0051] FIG. 2 illustrates an embodiment of a thermal contact model 200 using a thin film 210. The thermal contact model 200 is similar to the thermal contact model 100. The thermal contact model 200 includes a first material 202 and a second material 204. The materials 202 and 204 can be the same bulk sample material with a thermal effusivity b2 and a diffusivity α2. However, the materials 202 and 204 can be different materials with different thermal effusivities and diffusivities. A sensor 206 is disposed between the materials 202 and 204. The contact model 200 further includes a thin film 210 disposed between the material 202 and the sensor 206 and between the material 204 and the sensor 206. A contact area 208 exists between the two thin films 210, and a contact area 212 exists between the materials 202 and 204 and the thin film 210. The thin film 210 is said to have good contact with the sensor 206. However, in some embodiments, the contact between membrane 210 and sensor 206 may not be considered good contact. Contact area 208 and contact area 212 may have different characteristics or the same characteristics.

[0052] The sensor 206 can be a planar sensor embedded or sandwiched between the thin film 210 and the center between the two materials 202, 204. The sensor 206 can be a heat source heated with constant power for a predetermined period of time. Similar to the thermal contact model 100, the contact areas 208, 212 can be thin regions with a different thermal effusivity than the materials 202, 204 and the thin film 210.

[0053] If the membrane 210 is deemed to have good contact with the sensor 206, the thermal properties of the membrane 210 can be obtained in a manner similar to that of the model 100 described above. The thermal properties of the membrane 210 can be obtained according to the method of the contact model 100, but by replacing the reflection coefficient (R) with an appropriate effective R and inserting this into at least Equation 5. To calculate the thermal properties of the membrane 210, it is necessary to know the difference between the width of the membrane 210 as the distance from the sensor 206 to the contact area 212 and the width of the membrane 210 as the distance from the sensor 206 to the contact area 208 (this difference will be the approximate width of the membrane 210). Note that if there is no way to directly measure the width of the membrane 210, a time constant may be selected and used in the method and model, as described above.

[0054] Contact model 200 can also be used to measure the properties of contact area 212. If thin film 210 is a sample material of similar size and known properties to materials 202 and 204 instead of the example described above, the properties of contact area 208 can be calculated using a shorter test time. This shorter test time prevents heat from sensor 206 from interfering with contact area 212 and materials 202 and 204. A longer test time can then be used to calculate the properties of contact area 212. This method is applicable not only to the properties of contact between a sensor and a sample material, but also to the properties of contact between any two sample materials.

[0055] As described above, thermal contact model 200 can be used to measure and calculate various thermal properties of materials 202, 204, thin film 210, contact area 208, and contact area 212. For calculations and measurements using thermal contact model 200, sensor 206 or heating element is positioned at x=0 to create a symmetrical condition similar to contact model 100. In the above equations, the thermal effusivity of thin film 210 can be represented by b1, which is the thermal effusivity of contact area 108 described above.

[0056] FIG. 3 illustrates an embodiment of an asymmetric thermal contact model 300. The thermal contact model 300 includes a first material 302 and a second material 304, each in contact with a sensor 306. The materials 302 and 304 may be different materials with different thermal effusivities. The sensor 306 may be a planar sensor embedded or sandwiched in the contact area 308 between the first material 302 and the second material 304. The sensor 306 may be a heat source heated with a constant power for a predetermined period of time. The contact area 308 may be a thin region with a total width d (w1 + w2 = d) and a thermal effusivity b1. Here, the width from the sensor 306 to the material 302 is w1, and the width from the sensor 306 to the material 304 is w2.

[0057] The contact area 308 consists of the sensor 306 and the two physical contact areas of the materials 302 and 304. The heat source or sensor 306 does not need to be located in the center of the contact area 308, as shown in FIG. 3 . Note that the sensor 306 does not need to be located centrally between the first material 302 and the second material 304, but for the purposes of this model, the sensor 306 is assumed to be at x=0. As with models 100 and 200 described above, the contact area 308 can be thought of as a thin barrier separating the materials 302 and 304, corresponding to the surfaces of the contacting materials 302 and 304. This approximation allows the sensor 306 and the contact area 308 between the materials 302 and 304 to be treated as a single homogeneous layer.

[0058] Although model 300 represents contact area 308 as a single homogeneous layer, it can be more accurately described as a series of layers with different thermal properties, provided the layers are sufficiently thin and after a sufficiently long heating time, the single layer approximation holds.

[0059] Using thermal contact model 300, various thermal properties of materials 302, 304 and contact area 308 can be measured and calculated, as described above. For calculations and measurements using thermal contact model 300, sensor 306 or heating element is positioned at x=0. It will be understood that the temperature at sensor 306 follows Equation 6.

number

[0060] Here, T(x) follows the formula 7 below.

number

[0061] As mentioned above, widths w1 and w2 may not be known because they represent the contact area 308, which is a thin region. In that case, equations 6 and 7 can be rearranged to eliminate w1 and w2, as shown in equations 8, 9, and 10 below.

number

[0062] 4 shows an asymmetric thermal contact model 400 as a layered system. The asymmetric contact model 400 is similar to the thermal contact model 300, but with an additional material 410 between the contact area 308 and the material 304.

[0063] The temperature of the sensor can be calculated in a similar manner as described for the thermal contact model 300, but with the reflection coefficient R 23 Instead of the effective reflection coefficient R e23 where:

number

[0064] It will be appreciated that, as discussed above, non-linear fitting can be used to obtain the characteristics of the contact region in the models 300, 400. In some embodiments, there may be additional material adjacent to the material 304. In that case, the reflection coefficient R 34 Instead, the effective reflection coefficient R is calculated in the same way. e34 Furthermore, in some embodiments, there may be one or more additional materials adjacent to material 302 and / or there may be one or more additional materials adjacent to material 304. This allows for the thermal properties of any layered system to be determined, for example, by appropriately swapping the reflection coefficients. Such layered models or layered systems can describe systems where the in-plane dimensions are much larger than the inter-plane dimensions.

[0065] Each of the contact models described above can be used to determine the thermal properties of each contact region and material in a three-dimensional model. As an example, materials such as expanded polystyrene and stainless steel were modeled using at least the contact model 100 described above. The model results were then analyzed iteratively using nonlinear fitting across the entire data set to determine the time constant (t L ) was determined. This time constant can be used to determine the measurement period for longer test times to determine the exact thermal properties of the material.

[0066] The contact model 100 can be constructed as a three-dimensional model, with the same material used for the disk-shaped materials 102 and 104, and the sensor 106 similarly formed in a disk shape and acting as a transient planar heat source. The sensor was heated at constant power for a predetermined time (10 seconds) using materials 102 and 104: an extruded polystyrene foam sample (FIG. 5), an expanded polystyrene foam sample with a roughened surface (FIG. 6), a cut surface (FIG. 7), and a stainless steel 304 sample with a roughly sanded surface (FIG. 8). Materials 102 and 104 were also used: a stainless steel 304 sample with a polished surface (FIG. 9). The sensor was heated at constant power for a predetermined time (0.5 seconds).

[0067] FIG. 5 is a graph showing temperature over a 10-second period for a thermal contact model using extruded polystyrene. The graph shows the temperature results for the contact model 502, the temperature of the disk-shaped heat source or sensor 504, and the contact correction 506. Note that in FIGS. 6-9, the same reference numbers are used to indicate different results. In FIGS. 6-8, the temperature of a planar heat source 608 is also shown on the graph. It will be understood that a planar heat source can be thought of as an infinite plane, while a disk-shaped heat source can be thought of as having a finite diameter. The disk-shaped heat source 504 may provide a more accurate approximation of the heat source temperature.

[0068] In FIG. 5, F(t) and Tc(t) are plotted as a disk-shaped heat source 504 and a contact correction 506, respectively, to show the effect of contact between material samples. F(t) is the temperature without considering contact between materials, and is the temperature (T) in Equation 5 above. mdl The temperature result of the contact model 502 shown in the figure is equal to the model (T 3D (t)) after correction.

[0069] Note that at least the contact correction 506 shown in Figure 5 for extruded polystyrene foam shows a significant effect from the thermal contact or surface of the material, which approaches a constant temperature offset very slowly and cannot be explained by a simple power drop or temperature offset.

[0070] FIG. 9 is a graph showing temperature measurements from 0 to 0.5 seconds for a thermal contact model using polished stainless steel 304. F(t) (disk-shaped heat source 504) and Tc(t) (contact correction 506) are plotted to show the effect of contact between materials or between the polished surfaces of materials. This is similar to FIG. 8, which depicts a graph showing temperature measurements for roughly sanded stainless steel. As can be seen from FIGS. 8 and 9, the effect of thermal contact or material surfaces of the materials can be seen, particularly with respect to contact correction 506.

[0071] The method for determining the thermal properties of a contact region can be used to determine a variety of other properties of materials and models. For example, the method can be used to determine the time it takes for heat to penetrate from a sensor through a contact region into a second material, to correct for contact properties in measurements of bulk material properties, to automatically determine an appropriate measurement period for existing thermal measurement systems to minimize the effects of contact between materials, to calculate or determine the thermal properties of thin films, and to calculate or determine the thermal properties of layered systems. The above-described models 100-400 can also be used to correct for the finite and nonzero thermal properties of sensors, which are typically assumed to have negligible heat capacity and infinite thermal conductivity. The present invention eliminates the need for such approximations.

[0072] The method for determining thermal properties of a contact area can be implemented on a computer as a program for determining thermal properties of a contact area, correcting for contact properties in bulk material property measurements, automatically determining an appropriate measurement period to minimize the effects of material-to-material contact for existing thermal measurement systems, calculating or determining thermal properties of thin films, calculating or determining thermal properties of layered systems, and / or correcting for finite and non-zero thermal properties of sensors. When the method for determining thermal properties is implemented on a computer, the computer can receive data regarding the temperature of a sensor over time. The computer can also receive data regarding known properties of the bulk material to be analyzed. The received data can then be used to determine a temperature distribution of heat from the sensor to one or more materials. The temperature distribution can then be iteratively analyzed to isolate thermal properties of the material contact. After isolating the thermal properties through iterative analysis, the computer can output each of these properties. Thermal properties of the contact area that can be output include, but are not limited to, contact thermal conductance, the inverse of the contact thermal resistance of the contact area, and heat capacity per unit area.

[0073] In another embodiment, the computer can isolate the thermal properties of material contacts and then perform at least one correction for the contact properties in the measurement of bulk material properties, automatically determine an appropriate measurement period to minimize the effects of material contacts for an existing thermal measurement system, determine the thermal properties of thin films, or determine the thermal properties of layered systems. The computer can then output the corrected bulk material properties, the appropriate measurement period, the thermal properties of thin films, the thermal properties of layered systems, and / or the corrected finite and non-zero thermal properties of the sensor.

[0074] Using the thermal contact models 100-400 described above, the thermal properties of material contact can be isolated and analyzed as described above. As shown in Figures 5-9, contact has a significant effect on the transient plane heat source model. However, using the thermal contact models 100-400 and the described method, it is possible to decouple the contact heat content from the bulk material thermal properties, thereby stabilizing the measurement of bulk material properties over time and for different surface finishes.

[0075] The method for determining the thermal properties of the contact area described herein can use data measured and calculated from the beginning of the sensor heating period to the end of the sensor heating period. That is, in each of the illustrated examples, data from t=0 seconds to t=10 seconds, or from t=0 seconds to t=0.5 seconds, can be used. Existing methods must limit data to when the contact offset is constant. That is, to accurately determine the bulk material thermal properties in an analysis of an existing system, it is necessary to remove data measured and calculated from the beginning of the heating period. Furthermore, existing systems must be tested for a period long enough for the contact offset to become constant. The present method can use all data and does not require the sensor to be heated for a period long enough for the contact offset to become constant. For example, the method described above requires that data be limited to when the contact offset is constant. L The sensor heating time is shorter than that of conventional methods. Furthermore, the above-described models 100 to 400 are capable of separating and analyzing contact thermal characteristics without relying on a sensor.

[0076] It will be appreciated that the above-described model and method can be particularly useful for insulators, where short test times prove insufficient for measuring any thermal properties unless contact is considered. Measurements of effusivity for insulators that do not follow this methodology result in measurements of effusance, which are affected by the properties of the contact area and change over time as the thermal effusivity of the bulk material begins to dominate.

[0077] Those skilled in the art will appreciate that the methods and components shown and described in the figures may include components not shown in the figures. For simplicity and clarity of illustration, the elements in the figures are not necessarily drawn to scale and are merely schematic, and are not intended to imply limitations on the structure of the elements. It will be apparent to those skilled in the art that numerous variations and modifications are possible without departing from the scope of the invention described herein.

Claims

1. A method comprising: receiving temperature data from the sensor; and determining a temperature distribution of heat penetrating from the sensor into at least one material based on the received temperature data; the temperature distribution is determined based on the temperature data from the sensors over an appropriate measurement period; The method further comprises: applying a correction to the temperature distribution to obtain a corrected temperature distribution; repeatedly analyzing the corrected temperature distribution to determine thermal characteristics of the contact area; outputting a thermal characteristic of the contact area; The method, wherein the contact area includes the sensor and is an area between two of the at least one material.

2. The method of claim 1 , wherein the temperature data is the temperature of the sensor over time.

3. The method according to claim 1 or 2, wherein the iterative analysis is a non-linear fitting analysis.

4. The method according to any one of claims 1 to 3, further comprising: determining a thermal property of the at least one material using the temperature distribution and the thermal property of the contact area.

5. The method according to any one of claims 1 to 3, further comprising: automatically determining the appropriate measurement period of temperature data for determining thermal properties of the at least one material to minimize the effect of the contact area.

6. 3. The method of claim 1 or 2, a thin film between the sensor and the at least one material; and determining thermal properties of the thin film by repeatedly analyzing the corrected temperature distribution.

7. A method comprising: receiving temperature data from the sensor; determining a temperature distribution of heat penetrating from the sensor into two or more materials; the temperature distribution is determined based on the temperature data from the sensors over an appropriate measurement period; The method further comprises: applying a correction to the temperature distribution; and iteratively analyzing the corrected temperature distribution to determine thermal characteristics of the contact area; the contact area is an area between the two or more materials and includes the sensor; The method further comprises: outputting a thermal characteristic of the contact area.

8. 8. The method of claim 7, The method, wherein the temperature data is the temperature of the sensor over time.

9. 9. The method of claim 7 or 8, The method, wherein the iterative analysis is performed by performing a non-linear fitting analysis.

10. The method according to any one of claims 7 to 9, further comprising: determining thermal properties of the two or more materials using the temperature distribution and thermal properties of the contact area.

11. The method according to any one of claims 7 to 9, further comprising: automatically determining the appropriate measurement period of temperature data for determining thermal properties of the two or more materials to minimize an effect of the contact area.

12. The method according to any one of claims 7 to 11, The method, wherein there is at least one thin film between the sensor and at least one of the two or more materials.

13. 13. The method of claim 12, wherein the corrected temperature distribution is analyzed repeatedly to determine thermal properties of the at least one thin film.

14. A method comprising: disposing a sensor at a contact area between the first material and the second material; heating the sensor for a predetermined period of time; determining a temperature distribution of heat penetrating from the sensor into the first material or the second material; the temperature distribution is determined based on temperature data from the sensors during an appropriate measurement period; The method further comprises: repeatedly analyzing the temperature distribution; determining thermal characteristics of the contact area from the repeatedly analyzed temperature distribution; The method, wherein the contact area is an area between the first material and the second material and includes the sensor.

15. 15. The method of claim 14, further comprising applying a correction to the temperature distribution to obtain a corrected temperature distribution before repeatedly analyzing the temperature distribution, and repeatedly analyzing the corrected temperature distribution.

16. 16. The method of claim 14 or 15, further comprising: determining thermal properties of the first material and the second material using the temperature distribution and thermal properties of the contact area.

17. 16. The method of claim 14 or 15, further comprising: automatically determining the appropriate measurement period of the temperature data for determining thermal properties of the first material and the second material to minimize an effect of the contact area.

18. The method according to any one of claims 14 to 17, at least one thin film is present between the sensor and at least one of the first material and the second material; determining thermal properties of said at least one thin film by repeatedly analyzing said temperature distribution.

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