Related Experiment Video
Updated: Jun 8, 2026
07:42
Quasistatic Mechanical Testing for Computer-Aided Design and Manufacturing Occlusal Veneers Cemented to Milled Dentin Analog Material
Published on: December 20, 2024
Universal shapes formed by two interacting cracks
Melissa L Fender1, Frédéric Lechenault, Karen E Daniels
1Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA.
Physical Review Letters
|September 28, 2010
Summary
The "en passant" crack pattern, observed in elastic plates, results from two interacting cracks. These cracks form a universal 2:1 aspect ratio lenticular fragment, with shape determined by crack offset and pulling velocity.
Area of Science:
- Materials Science
- Fracture Mechanics
- Solid Mechanics
Background:
- The "en passant" crack pattern is a common phenomenon observed in elastic materials.
- This pattern arises from the interaction of two approaching cracks.
- Understanding its origins is crucial for predicting material failure.
Purpose of the Study:
- To investigate the fundamental mechanisms behind the "en passant" crack pattern.
- To determine the factors controlling the shape and scale of the released fragment.
- To develop a predictive model for this crack interaction.
Main Methods:
- Experimental setup involving notched rectangular elastic plates.
- Application of quasistatic uniaxial strain.
- Observation and analysis of crack propagation and fragment formation.
Main Results:
- Cracks propagate linearly until they interact, then curve to release a lenticular fragment.
- The fragment consistently exhibits a 2:1 aspect ratio across various materials.
- Crack shape follows a universal square root form, explained by a geometric interaction model.
Conclusions:
- The "en passant" crack pattern is governed by a universal geometric interaction between cracks.
- The initial crack offset and pulling velocity dictate the fragment's scale and formation time.
- A simple geometric model effectively explains the observed crack behavior and fragment morphology.
More Related Videos
Related Concept Videos
01:28Types of Non-structural Cracks in Concrete
Non-structural cracks are primarily of three types: plastic, early-age thermal, and drying shrinkage cracks. Plastic cracks are further classified into plastic shrinkage cracks and plastic settlement cracks.
Plastic shrinkage cracks typically form within hours after the concrete is poured. The concrete's surface dries faster than the bottom, creating tensile stress that the still-plastic concrete cannot withstand, leading to diagonal or randomly patterned cracks on the concrete surface.
Plastic...
Plastic shrinkage cracks typically form within hours after the concrete is poured. The concrete's surface dries faster than the bottom, creating tensile stress that the still-plastic concrete cannot withstand, leading to diagonal or randomly patterned cracks on the concrete surface.
Plastic...
01:23Behavior of Concrete Under Compressive Load
Concrete exhibits specific behaviors under different compressive loads. Understanding this is crucial for understanding its structural integrity. When concrete undergoes uniaxial compression, it tends to develop cracks that run parallel to the direction of the force. These parallel cracks stem from localized tensile stresses that occur perpendicular to the compression direction. Additionally, angled cracks may appear due to the formation of shear planes.
As the concrete specimen fractures under...
As the concrete specimen fractures under...
01:20Microcracking in Concrete
Microcracking in concrete refers to the tiny cracks that can form within the material even before any external load is applied. These microcracks typically occur at the interface between the coarse aggregate and the hydrated cement paste, often as a result of differential volume changes prompted by variations in stress-strain behavior, as well as thermal and moisture movement. Initially, these microcracks remain stable and do not grow substantially until the concrete is stressed to about 30...
01:25Imperfections in Crystal Structure: Point, Line and Plane Defects
A perfect crystal, in theory, has a uniform structure with the same unit cell and lattice points throughout. However, any deviation from this periodic arrangement is known as an imperfection or defect. These defects can be categorized into three types: point, line, and plane defects.Point defects occur when there is a deviation from the ideal due to missing atoms, displaced atoms, or additional atoms. These imperfections might occur due to imperfect packing during crystallization or because of...
01:18Deformations in a Symmetric Member in Bending
When analyzing the deformation of a symmetric prismatic member subjected to bending by equal and opposite couples, it becomes clear that as the member bends, the originally straight lines on its wider faces curve into circular arcs, with a constant radius centered at a point known as Point C. This phenomenon helps to understand the stress and strain distribution within the member more clearly.
When the member is segmented into tiny cubic elements, it is observed that the primary stress...
When the member is segmented into tiny cubic elements, it is observed that the primary stress...
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...