회사 소식 Case Study: Why Failure Analysis Must Combine Mechanics and Thermal Behavior？

In many industrial kiln applications, failure analysis is often oversimplified.

Typical explanations include:

• “The load was too high"
• “The roller quality was poor"
• “Thermal shock caused fracture"
• “The support structure failed"

However, in real high-temperature systems, ceramic roller failure is rarely caused by a single factor alone.

Most failures result from the interaction between:

• Mechanical stress
• Thermal behavior
• Structural constraint
• Material response
• Time-dependent damage accumulation

This is why reliable failure analysis must combine both mechanics and thermal behavior rather than treating them separately.

Traditional mechanical analysis typically focuses on:

• Static load
• Bending stress
• Shear force
• Support reactions
• Safety factor

These are important, but they do not fully represent actual kiln conditions.

For example:

A roller may appear mechanically safe under room-temperature calculations, yet still fail in service because thermal effects completely change the stress distribution.

At high temperature, the roller system is continuously affected by:

• Thermal expansion
• Uneven temperature distribution
• Cooling gradients
• Constraint from supports
• Expansion mismatch between components

These thermal effects generate additional mechanical stress.

In practice:

Thermal behavior often determines where stress concentrates.

When temperature distribution becomes non-uniform:

• One region expands more than another
• Internal deformation becomes constrained
• Tensile stress develops locally

Even small thermal gradients may create significant local stress in ceramic materials.

This is especially critical because ceramics are sensitive to tension.

Mechanical explanation alone:

• Local support force exists

But actual root cause may involve:

• Thermal contraction near support
• Restricted expansion
• Local tensile stress during cooling

Without thermal analysis, the real failure mechanism is missed.

Mechanical observation:

• Fracture occurred near the end face

But thermal contribution may include:

• Faster cooling at roller ends
• Temperature difference between center and edge
• Thermal bending during shutdown

Again, mechanics alone cannot explain the full process.

A roller may operate normally for months, then fail suddenly during shutdown.

Static load did not change.

The actual trigger may be:

• Rapid cooling
• Reverse thermal gradient
• Existing microcrack activation
• Thermal tensile stress exceeding local strength

Ceramic roller systems operate under coupled conditions:

These factors interact continuously during operation.

Ignoring either side leads to incomplete conclusions.

Many analyses simply compare:

• Calculated stress
• Material strength value

But actual failures often occur because:

• Local stress concentration develops
• Thermal tension appears
• Existing defects propagate

Cooling behavior is frequently underestimated.

In reality:

• Shutdown may generate higher tensile stress than operation
• Surface cooling may dominate crack initiation
• Thermal mismatch may control failure location

Temperature is not merely an operating parameter.

It directly changes:

• Stress distribution
• Support condition
• Contact pressure
• Structural deformation

Thermal behavior is part of the mechanical system itself.

• Bending stress
• Support reaction
• Contact condition
• Structural constraint

• Temperature gradient
• Cooling rate
• Thermal expansion path
• Heat distribution uniformity

• Thermally induced tension
• Constraint stress
• Thermal bending
• Fatigue accumulation

Most ceramic roller failures are not caused by a single extreme event.

Instead, damage accumulates gradually through:

• Repeated thermal cycling
• Localized support stress
• Uneven expansion
• Minor installation deviation
• Surface microdamage propagation

Failure occurs when multiple effects combine.

This is why field failures sometimes appear “unexpected" even when static calculations look safe.

Reliable failure analysis in high-temperature kiln systems must combine both mechanics and thermal behavior.

Mechanical analysis alone cannot fully explain:

• Stress concentration
• Crack initiation
• Thermal bending
• Shutdown failures
• Localized damage evolution

Similarly, thermal analysis without structural understanding is also incomplete.

In real ceramic roller systems, failure is usually driven by the interaction between:

• Mechanical load
• Thermal gradients
• Structural constraint
• Material response over time

Accurate engineering evaluation therefore requires a coupled thermo-mechanical approach rather than isolated analysis methods.

Shaanxi Kegu New Material Technology Co., Ltd.