Train Collapsible Interfaces With Downward Concavity Stiffness

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Solution Overview

Problem

Existing train designs with collapsible interfaces face challenges in evenly distributing the load during collisions, as all interfaces must be designed to withstand the highest load, leading to unnecessary stress on the first interface and inefficiencies in energy absorption due to linear stiffness curves.

Innovation Solution

The design incorporates collapsible structures with absorber elements that undergo plastic deformation, featuring a stiffness curve with downward concavity, allowing for a more even distribution of energy absorption across interfaces, reducing stress on the first interface and optimizing the size and weight of all interfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If all interfaces are designed to withstand the highest load (first interface specifications), then the train achieves uniformity and interchangeability requirements, but the first interface experiences unnecessary stress and energy absorption inefficiency

Engineering Contradiction:

Improveuniformity and interchangeability of interfacesVSAvoidstress on first interface

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent applies local quality by differentiating the absorber elements at the first interface from those at subsequent interfaces. The first interface uses absorber elements with higher energy absorption capacity to handle the highest load, while subsequent interfaces use absorber elements with reduced capacity. This localized differentiation allows each interface to be optimally sized for its specific load requirements rather than all interfaces being oversized to match the first interface specifications.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If collapsible structures provide linear resistance to compression, then energy absorption is distributed along the train, but the first interface still bears disproportionate stress and requires larger design dimensions

Engineering Contradiction:

Improveenergy absorption distributionVSAvoidload on first interface

Core Design Contradiction:

Loss of energyVSForce

Solution Approach 1:

The patent changes the parameter of absorber element capacity along the train configuration. By progressively reducing the energy absorption capacity parameter of absorber elements from the first interface to subsequent interfaces, the system creates a non-uniform distribution that matches the actual load profile. This parameter change allows the first interface to be designed for its specific high-load condition without requiring all interfaces to be oversized, thereby reducing the force stress concentration at the first interface.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If interface design is optimized for first interface load requirements, then collision safety is ensured, but train weight and space increase due to oversized subsequent interfaces

Engineering Contradiction:

Improvecollision safetyVSAvoidtrain weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies partial action by providing sufficient energy absorption capacity at each interface position rather than uniform excessive capacity throughout. The first interface receives full capacity needed for maximum load, while subsequent interfaces receive only the partial capacity they actually need based on their lower load exposure. This eliminates the waste of excessive capacity in later interfaces while maintaining overall collision safety.

Inventive Principle:

Principle #16Partial or excessive action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach results in a more efficient energy absorption and reduced stress on the first interface, enabling a lighter and more compact train design while maintaining effective collision safety.

Implementation Method 1

the absorber elements (18) are designed so as to undergo plastic deformation in a direction parallel to the direction (3) in the event of head-on or rear-end collision of the train

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP2699464B1Train provided with collapsible interfaces between the carriages

Publication Date: 2015.08.26 ANSALDOBREDA

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AI summary

A train (1) has a plurality of carriages (2) aligned along a longitudinal direction (3) and coupled to one another via interfaces (4), which are the same as one another and are provided with respective collapsible structures (18); each collapsible structure is plastically deformable when the interface (4) is subjected to a longitudinal compression higher than a given threshold (B) and has features such as to offer, during plastic deformation, a compressive strength substantially equal to that of a stiffness curve, which is set by design, increases in monotonic manner as a function of the longitudinal buckling, and has a downward concavity.