External tools: Rosette computation

The Rosette Computation tool is a standalone NVGate add-on that transforms raw strain gauge rosette signals into principal stress and principal stress angle time histories. It reads a time-domain measurement directly from the NVGate Player, performs the Mohr's circle computation sample by sample, and writes a new measurement back into the same NVGate project — ready to be analysed, displayed or exported like any other signal.

Downloads

File	Description
Download here	Standalone executable + all dependencies. Unzip and copy to C:\OROS\NVGate data\Links\
NVGate: Demo signal to test	Demo NVGate measurement with 3 rosette channels (rectangular, steel)

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Principle

A strain gauge rosette is a set of three strain gauges bonded close together on a surface and oriented at fixed angular offsets from each other. Because a single gauge only measures the normal strain in one direction, at least three gauges at known angles are needed to fully characterise the two-dimensional strain state at that point.

Once the three principal strains (ε₁, ε₂) and their orientation θ are known, the principal stresses (σ₁, σ₂) are derived using the plane-stress constitutive relations for a linear isotropic material.

The tool implements this calculation sample by sample over the full length of the signal, producing two additional time channels:

Output channel	Physical quantity	Unit
Principal Stress Magnitude	Maximum principal stress σ₁	Pa
Principal Stress Angle	Orientation of σ₁ w.r.t. gauge A	rad

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Supported Rosette Configurations

Three standard rosette layouts are supported:

Configuration	Gauge angles	Typical use
Rectangular / 45°	0° — 45° — 90°	General-purpose; most common in industry
Delta / 60°	0° — 60° — 120°	Equiangular rosette; more isotropic sensitivity
0° / 120° / 240°	0° — 120° — 240°	Alternative delta layout; same calculation as 60°

Mathematical formulas

Rectangular rosette (0° / 45° / 90°)

With εA, εB, εC being the strains measured by gauges A, B, C respectively:

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \text{Center} = \frac{\varepsilon_A + \varepsilon_C}{2}}

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \text{Radius} = \frac{1}{\sqrt{2}} \sqrt{(\varepsilon_A - \varepsilon_B)^2 + (\varepsilon_B - \varepsilon_C)^2}}

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \varepsilon_{max} = \text{Center} + \text{Radius} \qquad \varepsilon_{min} = \text{Center} - \text{Radius}}

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \sigma_1 = \frac{E}{1-\nu^2} \left( \varepsilon_{max} + \nu\,\varepsilon_{min} \right)}

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \theta = \frac{1}{2} \arctan2\!\left(2\varepsilon_B - \varepsilon_A - \varepsilon_C,\ \varepsilon_A - \varepsilon_C\right)}

Delta rosette (0° / 60° / 120° and 0° / 120° / 240°)

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \text{Center} = \frac{\varepsilon_A + \varepsilon_B + \varepsilon_C}{3}}

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \text{Radius} = \frac{\sqrt{2}}{3} \sqrt{(\varepsilon_A - \varepsilon_B)^2 + (\varepsilon_B - \varepsilon_C)^2 + (\varepsilon_A - \varepsilon_C)^2}}

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \varepsilon_{max} = \text{Center} + \text{Radius} \qquad \varepsilon_{min} = \text{Center} - \text{Radius}}

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \sigma_1 = \frac{E}{1-\nu^2} \left( \varepsilon_{max} + \nu\,\varepsilon_{min} \right)}

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \theta = \frac{1}{2} \arctan2\!\left(\sqrt{3}\,(\varepsilon_B - \varepsilon_C),\ 2\varepsilon_A - \varepsilon_B - \varepsilon_C\right)}

Note: The atan2 function is used instead of atan to correctly handle all quadrants, including the case εA = εC (zero denominator).

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Requirements

Item	Requirement
NVGate version	V12 or higher (V17+ recommended for OSFF format)
Signal format	OSFF measurement directory (NVGate V17+) or legacy .oxf
Signal type	Time-domain (static or dynamic channels)
Number of input channels	Exactly 3 strain gauge channels (any sampling rate)
Operating system	Windows 7 / 10 / 11 (32-bit Python runtime bundled)
NVGate running	Yes — the tool connects to NVGate via NVDrive to read the active player path and refresh the Project Manager

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Installation

Method 1: Copy the .exe to the NVGate Links folder (recommended)

1. Download RosetteAddon.exe (see Downloads below).
2. Copy the entire RosetteAddon/ folder to the NVGate external tools directory:

   C:\OROS\NVGate data\Links\

3. The tool will appear automatically in NVGate's Tools tab at next startup.

Method 2: Run the .exe directly

Double-click RosetteAddon.exe from any location. NVGate must be open and a signal must be loaded in the Player.

Note: The executable is self-contained — no Python installation or additional libraries are required on the target PC.

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Usage

Step-by-step

1. Open NVGate and load the measurement containing the rosette strain gauge channels in the Player.
2. Launch RosetteAddon.exe (from the Tools tab or directly).
3. In the Signal Channels card, select which NVGate input corresponds to each gauge:
   • ε A → gauge oriented at 0°
   • ε B → gauge oriented at 45° (or 60°)
   • ε C → gauge oriented at 90° (or 120°)
4. In the Material Properties card, enter the material constants:
   • Young's modulus E — in Pa (e.g. 210000000000 for steel, 70000000000 for aluminium)
   • Poisson's ratio ν — dimensionless (e.g. 0.3 for steel, 0.33 for aluminium)
5. Select the Rosette Type matching your sensor geometry.
6. Click COMPUTE.
7. The tool reads the signal, computes the rosette, and writes a new measurement named <original_name>_rosette in the same NVGate project.
8. NVGate's Project Manager is refreshed automatically — the new measurement appears immediately.

Status bar

The status bar at the bottom of the window reports progress in real time:

Colour	Message	Meaning
Amber	Computing... / Step 1/3...	Computation in progress
Green	Done — <name>	Computation completed successfully
Red	Error — ...	An error occurred (see details below)
Grey	Ready	Idle, waiting for user input

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Output measurement

The output measurement is written in the same NVGate project directory as the input, with the suffix _rosette appended to the original measurement name.

Example:

C:\OROS\NVGate data\Projects\MyProject\
  ├── Measurement1\               ← original (3 strain gauge channels)
  └── Measurement1_rosette\       ← created by the tool (5 channels)

The output measurement contains all the original channels plus the two computed channels:

Channel name	Content	Unit	Physical quantity
(original channels)	Raw strain data, unchanged	µε	Strain
Principal Stress Magnitude - A_B_C	σ₁ time history	Pa	Pressure
Principal Stress Angle - A_B_C	θ time history (orientation of σ₁)	rad	Plane Angle

The sampling rate, duration, and all device metadata are preserved from the input channels.

If the output measurement already exists (from a previous computation), it is automatically deleted and recreated. If it cannot be deleted (e.g., currently open in NVGate), a timestamped name is used instead.

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Typical material properties

Material	Young's modulus E (Pa)	Poisson's ratio ν
Steel (structural)	210 × 10⁹	0.30
Stainless steel	193 × 10⁹	0.28
Aluminium alloy	70 × 10⁹	0.33
Titanium alloy	110 × 10⁹	0.34
Cast iron	160 × 10⁹	0.26
Copper	120 × 10⁹	0.34

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Troubleshooting

Symptom	Likely cause	Solution
Error — no signal loaded in NVGate player	NVGate Player is empty or paused at the beginning	Load and play a signal in NVGate before launching the computation
Error — duplicate channel selection	The same channel is selected for two or more gauges	Select a distinct channel for each of ε A, ε B, ε C
Error — Young modulus is not a valid number	Non-numeric text in the E field	Enter a numeric value, e.g. 210e9 or 210000000000
Channel dropdown is empty	NVGate is not open, or measurement has no channels	Ensure NVGate is running with a measurement loaded in the Player
Output measurement not visible in NVGate	NVGate Project Manager not refreshed	Click Refresh PM in NVGate, or close and reopen the project
Stress values seem too high	Wrong unit for E (GPa entered instead of Pa)	Enter E in Pascals: 210 GPa = 210000000000 Pa
Angle output is always near zero	Gauges A and C have nearly identical strain	This is physically correct — it means the principal axis is nearly aligned with gauge A

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Version history

Version	Date	Changes
1.000b	2025-04	Initial public release. Supports rectangular (45°) and delta (60°/120°) rosettes. Compatible with NVGate V17 OSFF measurement format. Dark UI theme.
—	2024-11	Internal prototype (oxf format, NVGate V12–V16)

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See also

• NVGate Player
• External tools overview
• Strain gauge measurement with NVGate
• NVDrive — external tool communication protocol

Compute 2D main stress/strain values from rosette measurements

Compatibility : NVGate V12 or upper

A strain gauge rosette is a term for an arrangement of three strain gauges that are positioned closely together in order to measure strains along different directions in the component under test. Use of multiple strain gauges enables global stress amplitude and phase to be determined. The rosette add-on calculates this global stress from a rosette measurement.

Downloading

Download here april 2026 version

NVGate: Demo signal to test

Overview

"Rosette" tool is an NVGate Add-on to perform calculation of the angle / magnitude of the main stress from the rosette’s micro Strain :

It is advised to copy the application add-on "RosetteAddon.exe" within theNVGat "Link" directory "C: \ OROS \ NVGate data \ Links". Thus, it will be possible to access it via the "Tools" tab of NVGate :

How to use

This plugin works only on a signal already recorded, you must first load this signal in the player, then you can launch the plugin. Then you just need to fill in the configuration of the rosette, the corresponding inputs, the modulus of Young, Poisson Coeff and then compute. This may take some time depending on the size of the signal, even if the program "does not respond", wait for confirmation "Done" validating the correct operation.