Dynamic Penetrometer Measuring Head Shock Wave Filtering

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Solution Overview

Problem

Current dynamic penetrometers are limited in measuring soil characteristics over extended depths due to manual impact, lack precision in energy measurement, and are costly due to the use of piezoelectric materials, with no effective means to filter and process shock waves.

Innovation Solution

A measuring head equipped with deformation sensors, an accelerometer, and an absorption member that filters shock waves, allowing for optimized signal collection and processing, enabling reliable determination of soil characteristics up to 15 meters depth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If manual impact is used to operate the penetrometer, then the device is simple and inexpensive to operate, but the measurement depth is limited to 0-7 meters

Engineering Contradiction:

Improvemeasurement depthVSAvoidoperation complexity

Core Design Contradiction:

Length of moving objectVSEase of operation

Solution Approach 1:

The patent replaces manual mechanical impact with a controlled mechanical impact system using a dropping mass and guide structure. This allows deeper measurements (up to 15m) by providing consistent, repeatable impact forces without requiring manual operation at depth, resolving the contradiction between measurement depth and operational simplicity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If piezoelectric sensors are used to measure impact energy, then energy measurement is achieved, but the cost increases and measurement precision is insufficient

Engineering Contradiction:

Improveenergy measurement precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive piezoelectric sensors with strain gauges that are more cost-effective and can be arranged in Wheatstone bridge configurations for precise measurements. This substitution maintains measurement capability while reducing manufacturing costs and improving precision through the bridge circuit's error compensation features.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent uses composite measurement approaches combining strain gauges arranged in Wheatstone bridge configurations with careful structural design of the impactor and rod assembly. This composite approach achieves high measurement precision through the bridge circuit's ability to compensate for temperature and installation errors, while avoiding the high cost of piezoelectric materials.

Inventive Principle:

Principle #40Composite materials

3Reliability

If shock wave transmission is measured without filtering, then all signal information is captured, but signal processing becomes complex and unreliable

Engineering Contradiction:

Improvesignal reliabilityVSAvoidsignal processing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent incorporates preliminary signal conditioning directly into the measuring head design, including proper grounding, shielding, and Wheatstone bridge configurations that pre-filter and condition signals before transmission. This preliminary action ensures reliable signal capture from the start, reducing the need for complex post-processing and improving overall signal reliability.

Inventive Principle:

Principle #10Preliminary 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

The solution enhances the collection and processing of signals, providing accurate and reliable soil characteristic measurements over deeper depths, improving precision and reducing costs by filtering shock waves and using cost-effective materials.

Implementation Method 1

an absorption element (13) configured as a solid disc capping said free end (120), said absorption element (13) being made of a material suitable for filtering the waves transmitted to said rod assembly (9)

Methodology Applied

Scientific EffectShock wave filtering: Absorption (physical)

Implementation Method 2

at least two strain gauges (3, 4) arranged one above the other on said central rod (5)

Methodology Applied

Scientific EffectStrain gauge deformation: Piezoresistive Effect

Implementation Method 3

an accelerometer (6) arranged on said rod (5) between said two strain gauges (3, 4)

Methodology Applied

Scientific EffectAccelerometer measurement: Accelerometer

Data Source

PatentEP2817607B1Measuring head intended to be fitted to a dynamic penetrometer and method of measurement using such a measuring head

Publication Date: 2019.12.04 SOL SOLUTION

Figure 1~2
Figure 3~4
Figure 5

AI summary

This measuring head, which is intended to be fitted to a dynamic penetrometer, and is suitable for being attached to a drill string provided with a tip, comprises a driving head (12) intended to receive an impact to be transmitted, via the rest of the measuring head, to the drill string; and a central rod (5) for transmitting the impact from the driving head to the drill string, said central rod having a first end (50), which is turned towards the driving head, and a second end (51), which is opposite the first end and which is suitable for engaging with the drill string, said central rod being provided with at least one deformation sensor (3, 4). It comprises at least one absorption member (13) which is interposed between an impact receiving end portion (14) of the driving head (12) and the second end (51) of the central rod (5) and which is suitable for filtering the wave transmitted to the drill string when the end portion of the driving head receives an impact.