SCHOOL OF MECHANICAL ENGINEERING
FACULTY OF ENGINEERING
UNIVERSITI TEKNOLOGI MALAYSIA
SEMM 3622 (MATERIALS TECHNOLOGY)
SECTION 61
ASSIGNMENT
RO-ED ABULKHAIR
(A19EM4019 )
LECTURER:
DR MOHD ZAMRI BIN MOHD YUSOP
Table of Contents
INTRODUCTION ....................................................................................................................................... 3
Background: ............................................................................................................................................ 3
Critical Role of Turbine Blades: .............................................................................................................. 3
Importance of Understanding Failure Mechanisms: ............................................................................ 3
Objective of the Assignment:................................................................................................................. 4
Figure 1 (gas turbine blades)........................................................................................................... 4
Figure 2 (failure on gas turbine blades) .......................................................................................... 4
Operational Condition / Methodology and Failure Analysis ............................................................ 5
Operational Condition: ........................................................................................................................ 5
Mechanisms of Failure: ....................................................................................................................... 6
Figure 3 (Major causes of failure in gas turbine blades) ................................................................. 8
Figure 4 (Image of the gas turbine rotor along with the fractured blades in the failed Gas Turbine
engine unit) ..................................................................................................................................... 8
Suggestions for Improvement:........................................................................................................... 9
Key Findings from the Failure Analysis: ........................................................................................... 10
Conclusions: .................................................................................................................................. 11
Significance of Understanding Failure Mechanisms: .................................................................. 11
Implications for Future Designs or Materials: ............................................................................. 11
REFERENCE........................................................................................................................................ 13
Title: Failure Analysis of a Turbine Blade in
Gas Turbine Engine
INTRODUCTION
In this assignment, we embark on a comprehensive examination of the failure mechanism
surrounding a pivotal component – the turbine blade – nestled within the intricate confines of
a gas turbine engine. This component assumes a central role in the efficient propulsion of the
engine, and its untimely failure can precipitate catastrophic consequences, ranging from
operational disruptions to potential safety hazards. The meticulous selection of the turbine
blade for this analysis is grounded in its criticality to the engine's overall functionality, its
nuanced material composition, and the inherent complexity involved in dissecting the
multifaceted nature of its failure.
Background:
Gas turbine engines stand as paragons of engineering ingenuity, powering various applications,
including aircraft propulsion, power generation, and industrial processes. Operating on the
fundamental principles of thermodynamics, these engines are designed to convert the energy
from fuel combustion into mechanical work, propelling the entire system. At the heart of this
intricate machinery lies the turbine blade, an indispensable component that plays a pivotal role
in harnessing the kinetic energy of high-velocity gases generated during combustion.
Critical Role of Turbine Blades:
Turbine blades, situated within the hot gas flow path, serve as the workhorses responsible for
extracting energy from the high-temperature and high-pressure gases. This extracted energy is
subsequently converted into mechanical work, driving the turbine and, ultimately, the entire
engine. As a consequence of their pivotal role, turbine blades operate under extreme conditions,
enduring rapid temperature fluctuations, mechanical stresses, and exposure to corrosive
environments.
Importance of Understanding Failure Mechanisms:
The longevity and reliability of gas turbine engines hinge on the operational efficiency and
structural integrity of turbine blades. Recognizing the imperative nature of this component, this
assignment embarks on an in-depth exploration of the failure mechanisms associated with
turbine blades. A profound comprehension of these failure mechanisms is paramount for
engineering endeavors, as it facilitates informed decision-making in material selection, design
optimization, and operational practices.
Objective of the Assignment:
The primary goal of this assignment is to unravel the intricate web of factors contributing to
the failure of a turbine blade. By dissecting the failure mechanism, we aim to extract valuable
insights that can inform future designs, materials selection, and operational strategies. The
implications of this analysis extend beyond the singular case, offering a broader perspective on
enhancing the reliability, safety, and efficiency of gas turbine engines. Through this
exploration, we endeavor to contribute to the continuous evolution of engineering practices,
ensuring the robustness and resilience of critical components in gas turbine systems.
Figure 1 (gas turbine blades)
Figure 2 (failure on gas turbine blades)
Operational Condition / Methodology and Failure Analysis
Operational Condition:
Gas turbine engines operate under demanding conditions, and turbine blades are subjected to a
combination of mechanical, thermal, and environmental stresses. The operational conditions
for turbine blades are crucial for ensuring optimal performance and longevity. Here are key
factors that define the operational conditions of turbine blades:
1. Mechanical Loading:
o Turbine blades experience significant mechanical loading due to the high-speed
rotation of the turbine rotor. The centrifugal forces generated by this rotation
can be substantial, particularly in the outer regions of the turbine.
o Additionally, blades are exposed to axial and radial forces resulting from the
pressure difference across the turbine. These forces can cause bending and
twisting stresses, which require the blade material to have high strength and
fatigue resistance.
2. Temperature:
o Gas turbine engines operate at extremely high temperatures. The turbine blades
are exposed to hot gases produced by the combustion of fuel in the combustor.
Temperatures can range from hundreds to over a thousand degrees Celsius.
o Thermal gradients across the turbine blade can lead to differential expansion,
which further contributes to mechanical stresses. The high temperatures also
necessitate the use of advanced materials with excellent heat resistance, such as
nickel-based superalloys or ceramic matrix composites.
3. Aerodynamic Loading:
o Turbine blades experience aerodynamic forces as they interact with the hot
gases flowing over them. These forces can induce vibration and flutter,
requiring the blades to be designed to withstand dynamic loads.
o Aerodynamic loading also influences the cooling requirements of turbine
blades, as the cooling systems must effectively manage the heat generated
during operation.
4. Lubrication:
o The rotating and sliding components of a gas turbine, including the turbine
blades, require effective lubrication to minimize friction and wear. The
o
lubrication system ensures smooth operation and helps prevent damage to
critical components.
In some cases, advanced coatings or surface treatments are applied to enhance
the wear resistance of the blades and reduce the reliance on traditional
lubrication methods.
5. Corrosion and Erosion:
o Turbine blades are exposed to corrosive and erosive environments, especially
in the presence of contaminants in the combustion gases. Corrosion can degrade
the material over time, reducing its structural integrity.
o Erosion can occur due to the impact of solid particles carried by the air or
combustion products. This is particularly relevant in aviation applications where
turbines may encounter airborne debris.
6. Cyclic Loading:
o The start-up and shutdown cycles of gas turbine engines subject the turbine
blades to cyclic loading. This can contribute to fatigue and crack propagation
over time. Materials and designs must account for the cyclic nature of these
loading conditions.
7. Cooling Systems:
o To manage the extreme temperatures, turbine blades are often equipped with
internal cooling passages through which cooler air is circulated. Proper cooling
is essential to prevent thermal damage and maintain the structural integrity of
the blades.
Mechanisms of Failure:
Turbine blades in gas turbine engines are exposed to a variety of operational conditions that can
lead to different failure mechanisms. Understanding these failure mechanisms is crucial for
designing materials and structures that can withstand the harsh environments.
1. Fracture:
o Fracture occurs when a material fails under a static or dynamic load, often due
to high stress concentrations or flaws in the material. In turbine blades, fractures
can result from mechanical overloads, such as sudden increases in load or
impact events.
o Interaction with other failure mechanisms, such as fatigue or corrosion, can
initiate cracks that eventually lead to catastrophic fracture.
2. Creep:
o
o
Creep is the slow, time-dependent deformation of a material under constant load
and elevated temperatures. In gas turbine engines, the high operating
temperatures can cause creep deformation, especially in regions where stress
levels are high.
Creep can interact with other mechanisms, such as fatigue, as prolonged
exposure to elevated temperatures can accelerate fatigue crack growth.
3. Fatigue:
o Fatigue is the progressive and localized structural damage that occurs when a
material is subjected to cyclic loading. In turbine blades, the cyclical nature of
engine operation, including start-ups and shutdowns, contributes to fatigue.
o Fatigue cracks can initiate and propagate, leading to eventual failure, especially
when combined with other factors like corrosion or high-temperature oxidation.
4. Wear:
o
o
Wear is the gradual removal of material from the surface of a solid body due to
mechanical action. Turbine blades can experience wear from various sources,
including erosive particles in the gas stream and mechanical contact with other
components.
Wear can weaken the protective coatings on the blade, making it more
susceptible to other degradation mechanisms like corrosion.
5. Corrosion:
o Corrosion involves the degradation of a material through chemical reactions
with its environment. In gas turbine engines, corrosive environments can result
from the presence of water vapor, combustion by-products, and airborne
contaminants.
o Corrosion can interact with other failure mechanisms by promoting the
initiation and propagation of cracks, especially in regions where protective
coatings have been compromised.
These failure mechanisms often interact, creating a synergistic effect that accelerates the
degradation of turbine blades. For example:

Fatigue-Corrosion Interaction: Corrosion can act as a stress concentrator, promoting
fatigue crack initiation and propagation. Conversely, cyclic loading in a corrosive
environment can accelerate the corrosion process.

Creep-Fatigue Interaction: Prolonged exposure to high temperatures causing creep
deformation can create stress concentrations that contribute to fatigue damage. The
combination of creep and fatigue can lead to rapid crack growth.

Wear-Corrosion Interaction: Wear can expose fresh surfaces to the corrosive
environment, accelerating the corrosion process. Corrosion, in turn, can enhance wear
by reducing the protective properties of surface coatings.
Figure 3 (Major causes of failure in gas turbine blades)
Figure 4 (Image of the gas turbine rotor along with the fractured blades in the failed Gas Turbine engine unit)
Suggestions for Improvement:
Several recommendations can be made to increase the life of the turbine blade and mitigate
the identified failure mechanisms. These suggestions encompass material enhancements,
design modifications, and changes in operational procedures:
1. Material Enhancements:
o Advanced Alloys: Consider using advanced materials, such as improved
nickel-based superalloys or ceramic matrix composites, with enhanced hightemperature strength, creep resistance, and corrosion resistance.
o Surface Treatments: Apply specialized coatings or surface treatments to
enhance wear resistance and protect against corrosion. These coatings can also
provide thermal insulation to reduce temperature-induced degradation.
2. Design Modifications:
o Improved Cooling Systems: Enhance the internal cooling systems to more
efficiently manage temperature differentials across the turbine blade. Optimize
the cooling passages to target high-stress areas and minimize thermal gradients.
o Reduction of Stress Concentrations: Modify the blade design to reduce stress
concentrations by optimizing geometries and transitions. Consider using
smoother contours to minimize abrupt changes in cross-sectional areas.
o Damping Systems: Implement damping systems to mitigate vibrations and
reduce the risk of fatigue failures. These systems can absorb and dissipate
excess energy, minimizing the impact of cyclic loading.
3. Operational Procedures:
o Temperature Monitoring and Control: Implement advanced monitoring
systems to continuously assess and control the operating temperature of the
turbine blades. This helps prevent excessive temperatures that could lead to
thermal fatigue or creep deformation.
o Optimized Start-up and Shutdown Protocols: Develop optimized start-up
and shutdown procedures to minimize thermal gradients and cyclic loading
during transient periods. This can extend the fatigue life of the blades.
o Regular Maintenance and Inspections: Establish a robust maintenance
schedule with regular inspections for signs of wear, corrosion, or fatigue. Early
detection of potential issues allows for timely interventions and extends the
overall lifespan of the turbine blades.
4. Material and Operational Testing:
o
o
Testing Protocols: Implement rigorous testing protocols during the
manufacturing and quality control phases to identify any material defects or
inconsistencies before blades are put into service.
Operational Testing: Conduct operational testing under simulated conditions
to validate the performance of new materials or design modifications before
widespread implementation.
5. Root Cause Analysis and Continuous Improvement:
o Feedback Loop: Establish a feedback loop between failure analysis and design
processes. Regularly update designs based on lessons learned from failure
analysis to continuously improve turbine blade performance.
o Collaboration: Foster collaboration between materials scientists, engineers,
and operators to share insights and optimize turbine blade performance based
on real-world operational experiences.
6. Education and Training:
o Training Programs: Develop comprehensive training programs for operators
and maintenance personnel to enhance their understanding of turbine blade
behavior, failure mechanisms, and the importance of adherence to operational
guidelines.
Key Findings from the Failure Analysis:
1. Fracture Mechanism: The failure analysis revealed that the primary failure
mechanism of the turbine blade was fatigue, with the initiation and propagation of
cracks leading to catastrophic fracture.
2. Contributing Factors: The fatigue failure was influenced by factors such as high
cyclic loading during engine operation, stress concentrations in specific regions of the
blade, and the presence of corrosive environments accelerating crack growth.
3. Material Issues: Microscopic examination identified material anomalies, including
variations in microstructure and impurities, contributing to stress concentration points
and initiating fatigue cracks.
4. Operational Conditions: Thermal and mechanical operational conditions, including
high temperatures and cyclic loading during start-ups and shutdowns, played a
significant role in accelerating fatigue and thermal fatigue degradation.
Conclusions:
1. Dominant Failure Mechanisms: The failure analysis of gas turbine blades revealed
that fatigue, influenced by factors such as cyclic loading, high temperatures, and
corrosive environments, is a dominant failure mechanism.
2. Interconnected Factors: Failure is often a result of the interconnected nature of
mechanical, thermal, and material factors. Stress concentrations, corrosive conditions,
and material anomalies play pivotal roles in the degradation process.
3. Complex Operating Environments: Gas turbine blades operate in complex
environments with high temperatures, rapid temperature changes during start-ups, and
exposure to corrosive combustion by-products. These factors significantly contribute
to the challenges in ensuring component reliability.
Significance of Understanding Failure Mechanisms:
1. Informed Design Decisions: Understanding failure mechanisms allows for informed
decisions during the design phase. Engineers can optimize designs to minimize stress
concentrations, improve material selection, and enhance resistance to thermal and
mechanical loading.
2. Preventive Maintenance: Knowledge of failure mechanisms enables the development
of effective preventive maintenance strategies. Regular inspections, condition
monitoring, and early detection of potential issues can prevent catastrophic failures and
improve overall system reliability.
3. Safety and Performance: In the context of gas turbines, where reliability is critical for
both safety and performance, understanding failure mechanisms is paramount. It
ensures the development of systems that can operate safely and efficiently under
extreme conditions.
Implications for Future Designs or Materials:
1. Advanced Materials Development: Future gas turbine blades can benefit from
ongoing advancements in materials science. Research should focus on developing
materials with superior high-temperature strength, fatigue resistance, and corrosion
resistance to withstand the demanding operational conditions.
2. Innovative Cooling Solutions: Design modifications should include innovative
cooling solutions to manage temperature differentials effectively. Improved internal
cooling systems can enhance the thermal stability of gas turbine blades, preventing
thermal fatigue.
3. Integrated Design Approach: Future designs should adopt an integrated approach,
considering mechanical, thermal, and material aspects simultaneously. This ensures
that gas turbine blades are designed to operate optimally under a range of challenging
conditions.
4. Smart Monitoring Technologies: Incorporating smart monitoring technologies, such
as sensors and data analytics, can provide real-time insights into the health and
performance of gas turbine blades. This proactive approach allows for timely
interventions and extends the overall lifespan of components.
5. Collaboration Across Disciplines: Collaboration between materials scientists,
mechanical engineers, and operational experts is essential. Cross-disciplinary
collaboration fosters a comprehensive understanding of failure mechanisms, leading to
more robust designs and materials.
In summary, understanding failure mechanisms in gas turbine blades is critical for making
informed design decisions, implementing effective preventive maintenance, and ensuring the
safety and reliability of these crucial components. Ongoing advancements in materials and
design strategies will play a key role in enhancing the overall performance and longevity of
gas turbine systems.
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