Profiled Rail Vehicle Roof With Variable Material Thickness

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Solution Overview

Problem

Current rail vehicle roofs, particularly in local passenger transport, are heavy due to the uniform material thickness of profile sheets, which affects wheel loads and operational efficiency, and there is a need for a lighter and cost-effective solution without compromising structural integrity.

Innovation Solution

Designing a rail vehicle roof with a profile sheet where the material thickness in slope areas is reduced compared to the profile valleys and crests, allowing for a lighter and more cost-effective construction while maintaining structural rigidity, and incorporating a continuous thickness transition to minimize the risk of fractures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If uniform material thickness is used throughout the profiled sheet, then structural strength and stiffness are maintained, but the weight of the roof increases

Engineering Contradiction:
Improvestructural strengthVSAvoidroof weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent applies local quality by varying the material thickness according to the functional requirements of different roof regions. The profile valleys and peaks maintain full material thickness D for structural strength, while the slopes use reduced thickness d for weight reduction. This localized differentiation optimizes the strength-to-weight ratio by placing material only where structurally necessary.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The roof structure is segmented into distinct regions with different material thicknesses: thick regions at profile valleys and peaks for strength, and thin regions at slopes for weight reduction. This segmentation allows each part to be optimized independently for its specific functional requirements.

Inventive Principle:
Principle #1Segmentation

2Weight of moving object

If material thickness is reduced in slope areas, then roof weight decreases, but structural stiffness may be compromised

Engineering Contradiction:
Improveroof weightVSAvoidbending, buckling and compressive stiffness
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The invention applies local quality by concentrating full material thickness D at profile valleys and peaks where bending and compressive loads are highest, while using reduced thickness d only on slopes where structural demands are lower. This localized thickness distribution maintains overall stiffness while reducing weight.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The roof functions as a composite structure with two material thickness variants (d and D) integrated into a single profiled sheet. This composite approach allows the structure to achieve optimal mechanical properties by combining thick and thin regions in a functionally graded manner.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If abrupt transitions in material thickness are implemented, then manufacturing is simplified, but fracture risk increases at transition points

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidfracture resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-designing continuous thickness transitions in the roof structure before manufacturing or service. The gradual transition zones are built into the profiled sheet design, preventing abrupt thickness changes that would create stress concentration points and potential fracture locations during operation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3778335B1Rail vehicle with roof
Publication Date: 2022.04.06 SIEMENS MOBILITY GMBH
  • EP3778335B1 patent drawingFigure 1~3

AI summary

The invention relates to a rail vehicle with a roof. The roof of the rail vehicle is designed as a profiled sheet with alternating profile peaks and profile valleys, each connected to the others by slopes, wherein the slopes, or at least a portion of the slopes, have a smaller material thickness than the profile peaks and/or profile valleys, according to the invention. In the transitions between slope and profile peak and/or profile valley, the material thickness increases continuously from the material thickness of the slope to the material thickness of the corresponding profile peak and/or profile valley.