nouvelles de l'entreprise Why Increasing Component Size Does Not Increase Reliability?

In high-temperature systems, when components fail, a common response is:

Increase the size or thickness of the component

The assumption is:

•   Larger section → higher strength
•   Thicker structure → more reliable

However, in practice, failures often still occur.

The design logic is usually based on:

•   Increasing cross-sectional area
•   Increasing load capacity

This approach works for simple static systems.

But high-temperature applications are more complex.

Field observations show:

•   Larger components still experience deformation
•   Failure often occurs at similar locations
•   Service life does not increase proportionally

This indicates that size alone is not the determining factor.

In structural components such as beams and rollers:

Bending stress dominates behavior

The bending moment is influenced by:

•   Span length
•   Load distribution

Increasing component size does not change:

•   Span
•   Load path

The system behavior can be summarized as:

•   Load acts over a given span
•   Bending moment develops
•   Maximum stress occurs at critical sections

Even if section size increases:

The bending moment remains unchanged

Stress reduction is limited

At elevated temperature:

•   Creep deformation becomes significant
•   Material stiffness decreases
•   Thermal stress may develop

Larger components may:

•   Experience higher thermal gradients
•   Accumulate more internal stress

Typical features include:

•   Sagging or deformation over time
•   Crack initiation at edges or tensile zones
•   Failure under repeated loading

These are governed by system conditions, not size alone.

Increasing size improves:

•   Section modulus
•   Local strength

But does not address:

•   Span-induced bending
•   Thermal gradients
•   Contact conditions
•   Support design

Reliability is controlled by system behavior, not component size

Instead of increasing size:

•   Reduce span length
•   Optimize support configuration
•   Improve load distribution
•   Control temperature uniformity

A long-span beam in a kiln system:

•   Increasing thickness → limited improvement
•   Reducing span → significant reduction in bending stress

Structural design change is more effective than size increase.

Increasing component size:

Does not fundamentally improve reliability

Because:

•   System loading remains unchanged
•   Failure mechanisms are not addressed

Reliability in high-temperature SiC systems depends on:

•   Structural design
•   Load distribution
•   Temperature conditions

Not simply on component size.