American Journal of Applied Science and Technology
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VOLUME
Vol.05 Issue01 2025
PAGE NO.
1-3
Electrical Contacts Under Thermal and Electrical Stress:
Analytical and Experimental Investigations
Mathilda Wagner
Ilmenau University of Technology, Gustav-Kirchhoff-Straße, Ilmenau, Germany
Received:
18 November 2024;
Accepted:
20 January 2025;
Published:
01 February 2025
Abstract:
Electrical contacts play a crucial role in various electrical and electronic systems, where their
performance is significantly influenced by thermal and electrical stresses. This study presents a comprehensive
investigation into the electrical-thermal behavior of electrical contacts using both analytical modeling and
experimental validation. The analytical approach involves the development of mathematical models to predict
contact resistance, temperature rise, and degradation mechanisms under different loading conditions.
Experimental studies are conducted to validate the theoretical predictions and provide insights into material
behavior, contact wear, and failure mechanisms. The findings highlight the interplay between electrical and
thermal effects, emphasizing the importance of contact material properties, surface roughness, and
environmental conditions. This work contributes to the optimization of electrical contact design for improved
reliability and efficiency in practical application.
Keywords:
Electrical contacts, contact resistance, thermal stress, electrical stress, analytical modeling,
experimental analysis, contact degradation, material behavior, reliability, electrical-thermal performance.
Introduction:
Road Electrical contacts are fundamental
components in electrical and electronic systems,
enabling the transmission of electrical signals and
power
between
conductive
elements.
Their
performance is influenced by multiple factors,
including electrical loading, thermal effects, material
properties, and environmental conditions. The
reliability of electrical contacts is particularly critical in
high-power applications, where thermal and electrical
stresses can lead to contact degradation, increased
resistance, and eventual failure.
When an electrical current passes through a contact
interface, the constriction of current flow at micro-
asperities results in localized heating, known as Joule
heating. This thermal stress can cause softening,
oxidation, and material migration, ultimately affecting
the contact's electrical performance. Simultaneously,
electrical stress can induce arcing, erosion, and
degradation of the contact surface. Understanding
these interactions is essential for optimizing contact
materials, geometries, and operating conditions to
enhance reliability and efficiency.
This study aims to analyze the electrical-thermal
performance of electrical contacts through both
analytical modeling and experimental investigations.
The analytical approach develops mathematical
models to predict contact resistance, temperature rise,
and degradation mechanisms under varying conditions.
Complementary experimental studies validate these
models and provide insights into real-world
performance. By combining theoretical and empirical
analyses, this work offers a comprehensive
understanding of the key factors affecting electrical
contact performance under thermal and electrical
stress.
The remainder of this paper is organized as follows:
Section 2 discusses the theoretical background and
analytical modeling approach. Section 3 details the
experimental setup and methodology. Section 4
presents the results and discussion, comparing
analytical predictions with experimental findings.
Finally, Section 5 concludes with key insights and
potential future research directions.
METHODS
To comprehensively analyze the electrical-thermal
performance of electrical contacts under thermal and
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
electrical stress, both analytical modeling and
experimental investigations were conducted. This
section describes the methodology used to develop
theoretical models, the experimental setup employed
for validation, and the procedures followed for data
collection and analysis.
Analytical Modeling
The analytical approach aims to model the electrical
and thermal interactions at the contact interface. The
contact resistance, which significantly influences the
overall performance of electrical contacts, was
determined using Holm’s theory and Greenwood
-
Williamson’s asperity
-based model. These models
account for the constriction resistance due to surface
roughness and the real contact area, which is
influenced by mechanical and thermal factors.
The electrical-thermal behavior of the contacts was
modeled using Joule heating principles, where the heat
generated at the interface was computed as:
where is the heat generated, is the applied current, and
is the contact resistance. The temperature rise at the
contact junction was estimated using a one-
dimensional heat conduction equation:
where is the thermal conductivity of the contact
material and is the effective contact area. The effects
of thermal cycling, material softening, and oxidation on
contact performance were also incorporated into the
model to predict degradation over time.
Finite element analysis (FEA) simulations were
performed using ANSYS to validate the analytical
model. The simulations considered contact material
properties, applied forces, and electrical loads to
predict
temperature
distribution
and
stress
concentration at the interface.
Experimental Setup
To validate the theoretical models, experimental tests
were conducted using a custom-built test rig. The setup
consisted of a precision-controlled power supply, a
thermal imaging camera, a high-resolution digital
multimeter, and a contact force measurement system.
The test specimens were made of commonly used
electrical contact materials, including copper, silver,
and gold-plated alloys, to evaluate the influence of
material
composition
on
electrical-thermal
performance.
The contacts were subjected to varying electrical
currents ranging from 1 A to 50 A to study the effect of
current magnitude on temperature rise and resistance
variation. Additionally, mechanical loads from 1 N to 10
N were applied to examine how pressure influences the
real contact area and, consequently, the electrical
resistance.
A thermal camera with an infrared resolution of 640 ×
480 pixels was used to capture the temperature
distribution
across
the
contact
interface.
Simultaneously, resistance measurements were taken
using a four-wire Kelvin method to minimize lead and
contact resistance errors. The contact surfaces were
analyzed using scanning electron microscopy (SEM)
before and after testing to assess morphological
changes due to electrical and thermal stress.
Test Procedure
Each experiment was conducted in a controlled
environment to ensure consistency. The procedure
followed these steps:
Sample Preparation: Contact samples were cleaned
using isopropyl alcohol and dried to remove surface
contaminants. The initial surface roughness and
composition were measured using atomic force
microscopy (AFM) and energy-dispersive X-ray
spectroscopy (EDS), respectively.
Electrical Loading: The contacts were subjected to
stepwise increasing current levels while maintaining a
constant force. Resistance and temperature were
recorded at each step to analyze the dynamic behavior
under load.
Thermal Cycling: To simulate real-world operating
conditions, contacts underwent cyclic heating and
cooling between ambient temperature and a peak
temperature corresponding to the highest applied
current. The degradation in contact resistance over
multiple cycles was observed.
Post-Test Analysis: After testing, the contact surfaces
were examined using SEM to detect wear, material
transfer, and oxidation. Cross-sectional analysis was
performed to investigate subsurface changes due to
thermal stress.
Data Analysis
The experimental data were analyzed to compare with
theoretical predictions. Resistance variations were
plotted against applied current and force, revealing
trends in contact performance. The temperature
profiles obtained from thermal imaging were
compared with finite element model (FEM) results to
validate simulation accuracy.
A statistical analysis was conducted to assess the
reliability of measurements, ensuring that deviations
from theoretical predictions were within acceptable
margins. Correlation coefficients were calculated to
quantify the agreement between experimental and
analytical results.
Error Considerations and Limitations
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
To minimize experimental errors, measurements were
repeated five times for each test condition, and
average values were reported. Possible sources of error
included surface oxidation, minor variations in applied
force, and fluctuations in ambient temperature. To
account for these factors, corrections were applied
based on calibration tests performed prior to data
collection.
One limitation of this study is that the experiments
were
conducted
under
controlled
laboratory
conditions, which may not fully replicate harsh
environmental conditions such as humidity and
contaminants. Future work will involve studying the
effects of these external factors on contact degradation
and performance.
RESULTS AND DISCUSSION
The results from both analytical modeling and
experimental testing demonstrate a strong correlation
between contact resistance and thermal stress. As the
applied current increased, the temperature at the
contact interface exhibited a nonlinear rise due to Joule
heating, which was consistent with theoretical
predictions. Higher mechanical loads led to a reduction
in contact resistance due to an increased real contact
area, as confirmed by experimental data.
Thermal imaging analysis revealed that material-
dependent variations significantly influenced heat
dissipation. Silver-plated contacts exhibited the lowest
temperature rise due to their superior thermal
conductivity, while copper contacts showed moderate
performance. Gold-plated contacts, despite their
corrosion resistance, demonstrated higher resistance
under prolonged thermal cycling due to surface wear
and oxidation effects.
Scanning electron microscopy (SEM) analysis of post-
test surfaces confirmed the degradation mechanisms
predicted by the model, including localized melting,
material transfer, and increased surface roughness.
Oxidation layers were prominent in high-temperature
regions, further increasing contact resistance over
time. These findings highlight the importance of
selecting materials with high thermal and electrical
conductivity for prolonged operational reliability.
CONCLUSION
This study provides a comprehensive investigation into
the electrical-thermal behavior of electrical contacts
under thermal and electrical stress. Analytical models
successfully predicted resistance variations and
temperature rise, which were validated through
controlled experiments. The experimental findings
emphasize the role of contact materials, surface
conditions, and mechanical loads in determining
overall performance.
The insights gained from this research contribute to the
optimization of electrical contact design for high-
reliability applications. Future studies should focus on
the effects of environmental conditions such as
humidity and contaminants, as well as exploring
advanced materials and coatings to enhance contact
performance. The integration of real-world operational
scenarios will further strengthen the applicability of the
findings in industrial and commercial applications.
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