Thermal Joint Resistance of Conforming Rough Surfaces with Grease-Filled Interstitial Gaps

Savija, I.; Yovanovich, M. M.; Culham, J. R.; Marotta, Egidio

doi:10.2514/2.6763

Cited by 20 publications

(12 citation statements)

References 4 publications

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“…However, the heat flows from one solid to the other not only by means of conduction through the microcontacts but also by the microgaps when they are filled with a thermal interface material (TIM). For that reason,

φ_{g}

is defined, according to Reference 54 as:

φ_{g} = \frac{k_{g}}{Y},

where

k_{g}

is the TIM thermal conductivity and Y is the mean plane separation which depends on the normal contact pressure 54 . Y can be written as:

Y = 1.363 σ_{c} {[- l n (5.589 \frac{p_{n}}{H_{c}})]}^{0.5} .

…”

Section: Thermomechanical Contact Conditionsmentioning

confidence: 99%

“…The contact conductance depends on different geometric, thermal and mechanical parameters 52‐55 . Based on works, 52‐55 the general form of the contact conductance can be written as:

φ_{c} = 1.25 \cdot k_{c} \frac{m_{c}}{σ_{c}} {(\frac{| p_{n} |}{H_{c}})}^{0.95},

where,

k_{c} = 2 k^{A} k^{B} / (k^{A} + k^{B})

is the harmonic mean thermal conductivity of the interface.

H_{c} = 2 H^{A} H^{B} / (H^{A} + H^{B})

defines the contact microhardness,

σ_{c} = \sqrt{{(σ^{A})}^{2} + {(σ^{B})}^{2}}

is the effective joint surface roughness.…”

Section: Thermomechanical Contact Conditionsmentioning

confidence: 99%

“…The contact conductance depends on different geometric, thermal and mechanical parameters. [52][53][54][55] Based on works, [52][53][54][55] the general form of the contact conductance can be written as:…”

Section: Thermal Contact Conductancementioning

confidence: 99%

See 2 more Smart Citations

3D thermoelastic solids under non‐linear interface thermal and orthotropic frictional contact conditions

Ubero-Martínez

Rodríguez-Tembleque

Cifuentes-Rodríguez

et al. 2022

Numerical Meth Engineering

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This article presents a robust and efficient methodology to study three‐dimensional thermoelastic contact problems under orthotropic friction conditions, including the effects of non‐linear thermal contact conductance and convective boundary conditions at the interstitial contact zone. The proposed methodology considers the boundary element method to compute the thermomechanical influence coefficients and an augmented Lagrangian formulation to ensure the fulfillment of all these thermomechanical contact conditions. The resulting non‐linear equation set have been solved by an efficient proposed iterative Uzawa scheme. The proposed formulation has been validated by comparison with some available results in the literature and later on, it is considered to study how the thermoelastic contact variables are affected by both: the non‐linear interface thermal and the orthotropic friction conditions in different engineering problems such as a brake disc‐pad contact system.

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φ_{g}

is defined, according to Reference 54 as:

φ_{g} = \frac{k_{g}}{Y},

where

k_{g}

is the TIM thermal conductivity and Y is the mean plane separation which depends on the normal contact pressure 54 . Y can be written as:

Y = 1.363 σ_{c} {[- l n (5.589 \frac{p_{n}}{H_{c}})]}^{0.5} .

…”

Section: Thermomechanical Contact Conditionsmentioning

confidence: 99%

“…The contact conductance depends on different geometric, thermal and mechanical parameters 52‐55 . Based on works, 52‐55 the general form of the contact conductance can be written as:

φ_{c} = 1.25 \cdot k_{c} \frac{m_{c}}{σ_{c}} {(\frac{| p_{n} |}{H_{c}})}^{0.95},

where,

k_{c} = 2 k^{A} k^{B} / (k^{A} + k^{B})

is the harmonic mean thermal conductivity of the interface.

H_{c} = 2 H^{A} H^{B} / (H^{A} + H^{B})

defines the contact microhardness,

σ_{c} = \sqrt{{(σ^{A})}^{2} + {(σ^{B})}^{2}}

is the effective joint surface roughness.…”

Section: Thermomechanical Contact Conditionsmentioning

confidence: 99%

See 1 more Smart Citation

3D thermoelastic solids under non‐linear interface thermal and orthotropic frictional contact conditions

Ubero-Martínez

Rodríguez-Tembleque

Cifuentes-Rodríguez

et al. 2022

Numerical Meth Engineering

View full text Add to dashboard Cite

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“…An in-depth review of enhancement TIM, grease-filled interstitial gaps for joints, and thermal conductance models was conducted by Savija et al 13,14 In addition, Savija 15 conducted an investigation of thermal interface materials in the form of thin sheets of Grafoil GTA 005, 015, and 030. CHO-THERM 1671, just one of many polymeric materials with applications in microelectronic cooling, was also tested.…”

Section: Literature Reviewmentioning

confidence: 99%

Thermal Joint Conductance of Low-Density Polyethylene and Polyester Polymetric Films: Experimental

Kim

Marotta

Fletcher

2006

Journal of Thermophysics and Heat Transfer

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The flow of thermal energy across a joint where one or more surfaces come into contact is an important engineering consideration. Studies of metal/metal contacts at an interface have been investigated extensively and are well documented in the literature. Although equally important in many engineering application, the study of nonmetallic or organic contacting surfaces is still in its infancy. Currently, an elastic model exists for predicting the thermal performance of metal/polymer joints. In addition, a plastic model was recently proposed to account for plastic deformation of the contacting asperities. Both thermal contact models have been compared to experimental polymer layers that are relatively thick. The present objective was to investigate experimentally two commercially important polymeric film types for thermal conductance ranging from 254 to 12.2 μm in thickness under interface pressures varied from 103.4 (15) to 23,774.5 kPa (3450 psi). In each of the experimental tests, the ambient fluid at the contacting interface was air. One other objective was to conduct film nanoindentation measurements to possibly deduce a microdeformation mode. Surface metrology and film morphology are presented with a goal to incorporate these results into future modeling endeavors. The polymeric films investigated were low-density polyethylene and polyester, for example, Mylar ® . NomenclatureA a = apparent contact area, m 2 A t = true contact area at maximum load/penetration, m 2 d = distance between atoms, m E = Young's modulus, GPa F = applied force, N f g = combination of terms, dimensionless H = microhardness, GPa h b = bulk conductance, W/m 2 · K h c = contact penetration depth, nm h contact = contact conductance, W/m 2 · K h j = joint conductance, W/m 2 · K I g = gap conductance integral, dimensionless k = material conductivity, W/m 2 · K L = applied force, μN M = gas rarefaction parameter, m m = combined absolute asperity slope, rad n = plane index number P = apparent contact pressure, GPȧ Q = joint heat transfer rate, W R b = bulk resistance R c = contact resistance, K/W R g = gap resistance, K/W R j = joint resistance, K/W S = contact stiffness, d p/dh c T = temperature, K t = final thickness, m t 0 = original thickness, m Y = mean plane separation, m α = tip constant, 1.168 for Berkovich tip Presented as Paper 2005-760 at the AIAA Aerospace Sciences γ = plasticity index T j = joint temperature drop, K = see Eq. (24) θ = scattering angle, deg λ = incident wavelength, m ν = Poisson's ratio σ = effective surface roughness, √ (σ 2 1 + σ 2 2 ), m) ω = uncertainty parameter Subscripts c = contact e = elastic g = gap i = index number, interface p = polymer r = reduced s = harmonic 1, 2 = surface of solids 1 and 2

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“…Cooper et al [3] presented a common analytical approach to predict the thermal contact conductance in dependence of surface parameters such as roughness , mean slope m and surface load . This approach has been continuously extended by Mikic [4] and Yovanovich [5], also considering effects of interstitial fluids on the thermal contact conductance [6,7]. A detailed summary of proposed approaches can be found in the work by Yovanovich [8].…”

Section: Introductionmentioning

confidence: 99%

Investigating the influence of macroscopic surface structures on the thermal contact conductance using infrared thermography

Helmig¹,

Al-Sibai²,

Kneer³

et al. 2020

World Congress on Momentum, Heat and Mass Transfer

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The prediction of thermal contact conductance is commonly based on surface parameters such as roughness or mean slope. However, these parameters do not consider the orientation of macroscopic surface structures in contact, although this parameter may have a significant influence on the thermal contact conductance. To investigate this effect, three sets of specimens with different orientation of macroscopic surface structures are manufactured, all revealing the same roughness and mean slope. To quantify the thermal contact conductance, an infrared-camera measures the transient temperature response of two heated specimens pressed together by a hydraulic test bench. The obtained temperature data are then used as input for a conjugate gradient method quantifying the time-dependent thermal contact conductance. The results yield that specimen sets offering a conforming contact interface exhibit the highest conductance but show at the same time the highest standard deviation. In contrast, non-conforming contacts reveal both, lower mean values and standard deviation, the latter leading to less uncertainty in predicting thermal contact conductance. With the outlined findings, distinct surface structures can be chosen in order to achieve a desired range of thermal characteristics.

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Thermal Joint Resistance of Conforming Rough Surfaces with Grease-Filled Interstitial Gaps

Cited by 20 publications

References 4 publications

3D thermoelastic solids under non‐linear interface thermal and orthotropic frictional contact conditions

3D thermoelastic solids under non‐linear interface thermal and orthotropic frictional contact conditions

Thermal Joint Conductance of Low-Density Polyethylene and Polyester Polymetric Films: Experimental

Investigating the influence of macroscopic surface structures on the thermal contact conductance using infrared thermography

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