Multi-Axial Strength Testing Apparatus with Adjustable Axis Cross-Point

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Solution Overview

Problem

Existing multi-axes strength testing machines are limited in generating multi-stress conditions beyond a specific main stress ratio and require multiple actuators, leading to increased costs and potential fatigue failure at undesirable locations due to positional shifts during testing.

Innovation Solution

A multi-axial strength testing apparatus with a reduced number of stress loading actuators, featuring 1-axis testing structures that automatically adjust the cross-point of testing axes to the central area of the test piece, allowing for low-cost and stable multi-axes testing with minimal actuators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple actuators are used to build up 1-axis test structures, then multi-axes stress conditions can be generated, but the device complexity and cost increase

Engineering Contradiction:
Improvemulti-axes stress condition generationVSAvoidnumber of actuators
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The apparatus divides the multi-axes testing function into separate 1-axis test structures, each capable of independent operation. By segmenting the testing capability into modular 1-axis units that can be combined, the system achieves multi-axes functionality without requiring a completely new complex actuator system for each axis

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each 1-axis test structure is designed to be universal and can be used for testing in different axis directions. The same basic 1-axis structure can be replicated and arranged in different orientations (e.g., 0°, 45°, 90°) to create multi-axes testing capability, reducing the need for specialized actuators for each axis

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Ease of manufacture

If actuators are positioned to apply loads at end portions of test piece, then load application is simple, but positional shifts cause fatigue failure at undesirable locations

Engineering Contradiction:
Improveload application structureVSAvoidfatigue failure location control
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The base is designed to be movable along the testing axis direction, allowing dynamic adjustment of the 1-axis test structure's position. This movability enables the system to automatically adjust the cross-point of testing axes to coincide with the central area of the test piece, ensuring fatigue failure occurs at the desired central location rather than at arm joints

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates automatic adjustment mechanism where the movable base responds to positioning requirements to align the testing axis cross-point with the test piece center. This feedback-controlled positioning ensures that loads are applied in a way that prevents unintended fatigue failure at arm portions

Inventive Principle:
Principle #23Feedback

3Ease of operation

If testing axes cross at a point away from the central area, then actuator positioning is easier, but fatigue failure occurs at arm joints before central area

Engineering Contradiction:
Improveactuator positioningVSAvoidfatigue failure at central area
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The movable base allows the 1-axis test structure to dynamically reposition itself during setup and operation. This enables the system to automatically configure the testing axes to cross at the central area of the test piece, ensuring that fatigue failure initiates at the central location rather than at the arm joints where bending stresses would concentrate

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2930493B1Testing apparatus
Publication Date: 2019.06.12 HITACHI LTD
  • EP2930493B1 patent drawingFigure 1
  • EP2930493B1 patent drawingFigure 2
  • EP2930493B1 patent drawingFigure 3

AI summary

A strength testing apparatus, being less in the number of parts thereof and thereby cheap in the prices thereof, has a plural numbers of testing axes (13, 14, 15), each of which breaks a teste piece in a central area thereof. In the testing apparatus, including a plural number of 1-axis testing structures therein, the each 1-axis testing structure, comprises: an actuator (1, 2, 3), which is configured to move linearly, thereby to apply a load onto a test body; an actuator fixing base (40, 41, 42), which is configured to fix the actuator (1, 2, 3) at a predetermined position; a reaction base (7, 8, 9) comprising a chucking tool (11a), which is configured to chuck a test piece, in a pair with another chucking tool (11b), which is provided at end portion of the actuator (1, 2, 3) ; and a base (6), which is configured to connect the actuator fixing base (40, 41, 42) and the reaction base (7, 8, 9), wherein all of testing axes (13, 14, 15), each almost passing through an axial center of each actuator (1, 2, 3), come across at one point (20), and the 1-axis testing structures are arranged so that they are included in a same plane.