Mohrs Circle Calculator

Welcome to this engineering tutorial where we will explore the concept of Mohr's Circle and its calculator. Mohr's Circle is a graphical method used in solid mechanics to visualize and analyze stress states and their transformations. It is a fundamental tool in materials engineering, civil engineering, and mechanical engineering. In this tutorial, we will introduce the concept, share interesting facts, explain the formula used in Mohr's Circle calculations, provide a real-life example, and equip you with the knowledge to understand and use Mohr's Circle for stress analysis.

Mohrs Circle for 2d Stress Analysis Calculator
Normal Stress XX MPa
Shear Stress xy MPa
Normal Stress YY MPa
Rotation about Principal Axes °
Mohrs Circle Calculator Results
Ïyx = MPa
Mean Stress (C) = MPa
Principal Stress Imax (σ1) = MPa
Principal Stress IImin (σ2) = MPa
Maximum Shear Stress (Ïmax) = MPa
Von Mises Stress (σVM) = MPa

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Learn about the Mohr's Circle calculator and its practical application in engineering. This tutorial provides an introduction to the concept, interesting facts, explanation of the formula, a real-life example, and more

Interesting Facts about Mohr's Circle

Before we dive into the calculations, let's discover some fascinating facts about Mohr's Circle:

  • Mohr's Circle was developed by Christian Otto Mohr, a German civil engineer and mechanical engineer, in the 19th century.
  • It is a graphical representation of stress transformation in materials under various loading conditions.
  • Mohr's Circle provides a visual representation of principal stresses, maximum shear stress, and stress invariants.
  • The construction of Mohr's Circle involves plotting stress components on a coordinate plane using a polar coordinate system.
  • Mohr's Circle is widely used in materials testing, structural analysis, geotechnical engineering, and mechanical design.
  • It simplifies the interpretation and analysis of complex stress states and aids in determining the safety and stability of structures.

Formula for Mohr's Circle

Mohr's Circle is constructed using the following formulas:

σavg = (σ1 + σ2) / 2

τmax = (σ1 - σ2) / 2


  • σavg is the average stress
  • σ1 and σ2 are the principal stresses
  • τmax is the maximum shear stress

The principal stresses can be obtained through stress analysis, and with these values, we can plot Mohr's Circle to visualize the stress state and perform further calculations.

Example: Real-Life Application of Mohr's Circle

Let's consider an example to better understand how Mohr's Circle is used in real-life engineering scenarios. Suppose we have a structural component subjected to a biaxial stress state. The component experiences a tensile stress of 50 MPa in the x-direction (σx) and a compressive stress of 20 MPa in the y-direction (σy). We can calculate the average stress (σavg) and maximum shear stress (τmax) using the formulas mentioned earlier:

σavg = (σ1 + σ2) / 2 = (50 MPa + (-20 MPa)) / 2 = 15 MPa

τmax = (σ1 - σ2) / 2 = (50 MPa - (-20 MPa)) / 2 = 35 MPa

Now, we can plot Mohr's Circle using these values. Mohr's Circle is a graphical representation of stress components on a coordinate plane, with σ on the x-axis and τ on the y-axis. The center of the circle represents the average stress (σavg) and the radius represents the maximum shear stress (τmax). In this case, the center of the circle is at (15 MPa, 0) and the radius is 35 MPa.

Mohr's Circle allows us to determine additional information about the stress state. For example, the principal stresses (σ1 and σ2) can be obtained by adding and subtracting the radius from the center of the circle:

σ1 = σavg + τmax = 15 MPa + 35 MPa = 50 MPa

σ2 = σavg - τmax = 15 MPa - 35 MPa = -20 MPa

In this example, the principal stresses are σ1 = 50 MPa and σ2 = -20 MPa. We can also determine the angle (θ) at which the maximum shear stress occurs:

θ = 0.5 × atan(2τmax / (σ1 - σ2)) = 0.5 × atan(2 × 35 MPa / (50 MPa - (-20 MPa)))

Simplifying the equation:

θ ≈ 43.6°

Now we know that the maximum shear stress occurs at an angle of approximately 43.6° in the coordinate system.

In real-life engineering applications, Mohr's Circle is extensively used in structural analysis, geotechnical engineering, and materials testing. It helps engineers determine the safety and stability of structures, evaluate failure criteria, and design structures to withstand complex stress states. For example, in civil engineering, Mohr's Circle is used to analyze soil mechanics, calculate bearing capacity, and assess the stability of slopes.

In materials engineering, Mohr's Circle is used to analyze the mechanical behavior of materials under different loading conditions. It aids in understanding the failure mechanisms, predicting material failure, and designing structures with appropriate strength and durability. Mohr's Circle is also utilized in mechanical engineering for analyzing the stress state in machine components, such as gears, shafts, and beams, to ensure their safe and efficient operation.

One practical example of using Mohr's Circle is in the design and analysis of a bridge. Bridges are subjected to various loads, including dead loads (the weight of the bridge itself), live loads (traffic loads), and environmental loads (wind, temperature changes). By analyzing the stress state at critical sections of the bridge using Mohr's Circle, engineers can determine the maximum stresses and potential failure modes. This information is crucial for selecting suitable materials, designing reinforcement, and ensuring the bridge's structural integrity and safety.

Additionally, Mohr's Circle is valuable in the field of geotechnical engineering. Soil mechanics involves studying the behavior of soils under different loading conditions. By applying Mohr's Circle to soil stress analysis, engineers can assess factors such as soil stability, bearing capacity, and slope stability. Understanding the stress distribution in soils helps in designing foundations, retaining walls, and other geotechnical structures to ensure their stability and prevent catastrophic failures.

To summarize, Mohr's Circle is a powerful tool in engineering for visualizing and analyzing stress states. It simplifies complex stress calculations and provides insights into the behavior of materials and structures. By understanding the principles behind Mohr's Circle and utilizing the formulas, engineers can gain valuable information about the stress distribution, principal stresses, and shear stresses in various applications. This knowledge enables them to make informed design decisions, assess structural integrity, and ensure the safety and reliability of engineering projects.

Thank you for going through this tutorial on the Mohr's Circle calculator. We hope you found it informative and helpful in understanding this essential concept in engineering analysis. If you have any further questions, feel free to ask. Happy engineering!