Name: wheatstone bridge output for strain gauge design
Uploaded: 2024-04-11T12:48:31.000Z
Duration: 1 min 15 s
Channel: JoVE

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design-example-strain-gauge-bridge-or-wheatstone-bridge

Design Example: Strain Gauge Bridge or Wheatstone Bridge

Ein Dehnungsmessstreifen, ein Aufnehmer, der mechanische Dehnung in elektrische Signale umwandelt, wird häufig zur Kraftmessung verwendet.
Die Aufgabe des Ingenieurs besteht darin, die Wheatstone-Brückenschaltung zu entwerfen, Dehnungsmessstreifen in jedem Arm zu haben und die erforderliche Verstärkung für die Ausgangsspannung zu identifizieren. Dabei wird davon ausgegangen, dass die aufgebrachte Kraft den Widerstand von zwei Dehnungsmessstreifen erhöht, während der Widerstand bei den anderen beiden abnimmt. Auch der Zusammenhang zwischen der Ausgangsspannung der Brücke und der Widerstandsänderung ist bekannt.
Dies kann mit dem Theorem von Thevenin erreicht werden.
Mit Kenntnis der Eingangsspannung werden zunächst die Ströme im oberen und unteren Zweig bestimmt. Diese Werte werden dann in das Ohmsche Gesetz eingesetzt, um die Thevenin-Spannung zu berechnen.
Zur Berechnung des Thevenin-Widerstands wird die Quelle entfernt und der äquivalente Widerstand in vereinfachter Form bestimmt.
Aus der Thevenin-Ersatzschaltung wird die Ausgangsspannung der Brücke nach der Spannungsteilungsregel berechnet.
Der Vergleich der erhaltenen Beziehung mit der bekannten Beziehung ermöglicht die Bestimmung der Verstärkerverstärkung, die erforderlich ist, um die Schaltung so zu gestalten, dass sie innerhalb des gewünschten Bereichs arbeitet.

designbeispiel: dehnungsmessstreifen-brücke

Die Nutzung von Dehnungsmessstreifen als Wandler zur Umwandlung von mechanischer Dehnung in elektrische Signale ist eine gängige Praxis in verschiedenen Ingenieuranwendungen. Diese Dehnungsmessstreifen werden häufig in Wheatstone-Brückenschaltungen integriert, um Parameter wie Kraft oder Druck genau zu messen. In diesem Zusammenhang zeigt jedes Element innerhalb der Schaltung einen Widerstand, der subtile Variationen erfährt, wenn es mechanischer Dehnung ausgesetzt ist. Das primäre Ziel ist es, winzige Variationen in der kleinen Spannungsausgabe in eine deutlicher erkennbare Spannungsausgabe umzuwandeln, die bequem mit einem Voltmeter abgelesen werden kann. In der Funktion des Ingenieurs umfassen die Verantwortlichkeiten das Erstellen eines Dehnungsmessstreifen-Designs und die Bestimmung der notwendigen Verstärkung, um Änderungen im Widerstand genau widerzuspiegeln. Dies beruht auf der Anwendung des Theveninschen Theorems, das den Zusammenhang zwischen der Ausgangsspannung der Brückenschaltung und den Variationen im Widerstand herstellt. Das Verfahren beginnt mit der Berechnung der Thevenin-Spannung, die die anfängliche Bestimmung der Ströme in den oberen und unteren Zweigen der Schaltung erfordert. Infolgedessen werden diese berechneten Stromwerte in das Ohmsche Gesetz eingesetzt, um die Thevenin-Spannung abzuleiten. Gleichzeitig wird der Thevenin-Widerstand bestimmt, indem die Spannungsquelle in einer vereinfachten Konfiguration entfernt wird. Der Thevenin-Äquivalentschaltkreis findet die Ausgangsspannung der Brücke durch die Regel der Spannungsteilung. Das kritische Ergebnis dieser Analyse ermöglicht die präzise Bestimmung des Verstärkungsfaktors des Verstärkers, der für das Design des Schaltkreises erforderlich ist, um effektiv innerhalb des angegebenen Betriebsbereichs zu funktionieren.

Designbeispiel: Dehnungsmessstreifen-Brücke

Ein Dehnungsmessstreifen, ein Aufnehmer, der mechanische Dehnung in elektrische Signale umwandelt, wird häufig zur Kraftmessung verwendet.
Die Rolle des Ingenieurs umfasst ...

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wheatstone bridge output for strain gauge design

A strain gauge and Wheatstone bridge work together to turn mechanical strain into an electrical signal. In engineering, this setup is often used to measure force or pressure. Each part of the bridge has a resistance that changes slightly when strain is applied.

The main goal is to turn a very small voltage output into a larger, easier-to-read signal. A voltmeter can then measure that output more clearly. To do this, an engineer designs the strain gauge circuit and figures out how much amplification is needed so the resistance change is shown accurately.

The analysis uses Thevenin's theorem, which links the bridge output voltage to changes in resistance. First, the Thevenin voltage is found by calculating the currents in the upper and lower branches of the circuit. Those currents are then used with Ohm's law to determine the voltage.

Next, the Thevenin resistance is found by removing the voltage source and simplifying the circuit. The Thevenin equivalent circuit is then used with the voltage division rule to find the bridge output voltage. This result helps determine the amplifier gain needed for the circuit to work in the correct operating range.

Wheatstone Bridge Output for Strain Gauge Design

wheatstone-bridge-output-for-strain-gauge-design

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design example: strain gauge bridge or wheatstone bridge

A strain gauge and Wheatstone bridge work together to turn mechanical strain into an electrical signal. In engineering, this setup is often used to measure force or pressure. Each part of the bridge has a resistance that changes slightly when strain is applied. The main goal is to turn a very small voltage output into a larger, easier-to-read signal. A voltmeter can then measure that output more clearly. To do this, an engineer designs the strain gauge circuit and figures out how much...

key terms and concepts

Learn how a strain gauge and Wheatstone bridge convert strain into voltage, and how Thevenin's theorem helps find the amplifier gain needed.

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Wheatstone Bridge Output for Strain Gauge Design

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