Failure Of The Failure And Predicting The Mechanical Properties Of Composite Materials

This report details the process for the design of a composite laminate tube, the software package 'MathCAD' was used to determine a lamina design with a configuration that avoids mechanical failure under loading conditions. It was also used to obtain twist angles and maximum stresses for specific lamina wind up angles. The report will provide analysis of the methods used to obtain these criteria.

This paper discusses the different properties of composite materials under static testing condition to determine the effect of aging due to change in temperature and moisture content. Effects on tensile, shear, impact, stiffness and fatigue parameters are studied. For each property, application specific composite materials are taken into consideration with different stacking sequence and number of plies. Different samples of these are then introduced to different hygrothermal environments for example: temperatures ranging from -50 degree Celsius to +50 degree Celsius or kept in wet conditions for 24 hours at different temperatures of 21, 37 and 50 degree Celsius etc. Different tests are performed based on the material property to observe a change from the initial unaged specimen. To study every property a different test method is discussed. A final comparison for each property between the unaged and aged specimen is shown in order to see the property’s dependence on temperature and moisture. This comparison highlights the temperature and moisture dependent properties and showcase a trend. Properties like tensile modulus, shear modulus, shear strength, flexural stiffness and fatigue life show a decrease with increase in temperature and moisture content while Poisson’s ratio and impact strength increase with increase in temperature and moisture content.

Principal Investigator Dr. Roy Xu (US citizen) worked as an aerospace structural engineer in China. He came to the US and received his Ph.D. in Aeronautics and Materials Science from California Institute of Technology in 2002. He started his interdisciplinary faculty career as a civil engineering faculty at Vanderbilt University, and a mechanical and aerospace engineering faculty at University of Texas at El Paso and New Mexico State University (NMSU). His honor and award include an Office of Naval Research (ONR) Young Investigator Award in 2003, and a Fellow of the American Society of Mechanical Engineers (ASME) in 2012. He is the Chair of the ASME Fracture and Failure Mechanics Technical Committee. As an author of 46 journal papers,

Composites, is a material that made with two or more different material. People can see or use it anytime, anywhere. Composite materials can provide different advantages from mixing different materials, and usually combined metal (aluminum), polymers (epoxy) or ceramic (silicon). One of the most common example for the composites will be fishing rod. Nowadays fishing rod usually make with glass fiber/ carbon fiber and epoxy. Which glass fiber or carbon fiber are brittle but strong, and epoxy can provide a high mechanical properties. Result of the fishing rod can be have a better toughness, and lightweight. Because of that in this lab, the main objective is going to use the optical microscopy and find out the fiber’s alignment, the structure pattern and the mechanical properties from the fishing rod.

Composite materials are the engineering materials made from two or more constituent materials they remain separate and distinct on a macroscopic level but forming a single component or Composites can defined as materials that consist of two more chemically and physically different phases separated by a distinct interface(matrix phase and dispersed phase). The different systems are combined judiciously to achieve a component with more and more useful structural or functional properties non-attainable by any of the constituent alone. In the composites usually Matrix phase is the primary or base phase having a continuous character or continuous molecular chain. But these Matrixes are usually less hard and more ductile phase. In composites it holds the dispersed (reinforcing) phase, shares a load with it. The Dispersed phase is encapsulated in the matrix in a discontinuous form called a secondary phase. This Secondary phase

This deals with bending Finite Element Analysis of the aircraft wing using commercial software ANSYS. An aircraft wing is made of composite with fibre angles in each ply aligned in different direction. Various air foil thickness and ply angles were considered to study the effect of bending-torsion decoupling. The laminate characteristics are usually calculated using the number of layer, stacking sequence, geometric and mechanical properties. A finite number of layers can be combined to form so many laminates. The only restriction that is imposed on the laminate as an element of composite structure concerns its total thickness which is assumed to be much smaller than the other dimensions of the structure.

As mentioned above, composite materials are now being used in a wide range in the Aircraft Industry. They have now allowed the engineers to design and overcome difficult

The purpose of this lab is was to expose students to the manufacturing, fabrication, and testing of composites. In addition, it provides students with experience analyzing tensile and bending failures of composites. Three tensile specimens and two bend test specimens were tested during this lab. The tensile specimens were a wet lay-up of bi-directional E-glass, and the bend specimens were made up of a nomex honeycomb core with pre-preg uni-carbon faces. The three tensile specimens were tested, their elastic modulus and ultimate tensile strength calculated, and these value were compared to published approximately equivalent material properties. The two bend test specimens were tested, their face bending stresses were calculated, the shear stress in the core was calculated, and the bending and shear stresses were compared to published approximately equivalent material properties. A failure mode analysis was conducted for both the tensile and bend test specimens. This report summarizes the theory, procedure, and machines associated with the lab. Furthermore, it graphically and verbally displays the results draw from lab, and provides conclusions to improve the lab in the future.

However, modeling of ceramic matrix composites could be much more complex due to the unique feature of this type of material: 1) the fracture and brittle behavior of materials; and b) the nonuniform distribution of porosity in the ceramic matrix. CMCs are comprised of individual layers with unique material properties dependent on fiber orientation within the polymer matrix which is typically in a woven pattern. Therefore, CMCs often exhibit anisotropic or orthotropic properties, and have lower strains and higher degrees of fragmentations than metallic materials during machining. The unique features of CMCs make simulations more challenging due to the complex nature of the problem considering material nonlinear fracture, anisotropic or orthotropic property and multi-phase interaction apart from dynamic loading and plastic deformation in machining of metals.

Aerospace design applications rely heavily on weight reduction, structural integrity and optimize performance. Engineers and designers have adopted carbon fiber composite due to its high modulus reinforcement fibers embedded in an epoxy matrix.

In almost every structure, beams or flexural members are found. It is important then to understand how different beams will reach to different situations. To evaluate flexure and stress distribution in a simple beam, seen in Figure 1, a fundamental four point bending test can be conducted to induce pure bending on the center of a wide flange shape beam.

Tests like three-point bending can be used to evaluate the properties of the entire specimen as a structure, so it is important to understand the mechanical response when there is an applied load to the composite structure. It will be a lot easier to understand for homogeneous materials, since they respond in the same behavior when loaded in different orientations. However, when dealing with composite material, the anisotropy created by the orientations of reinforcing fibers for each ply has to be taken into account. Such kind of material response and structure needs an orthotropic material model coupled with an assumption of plane stress. The stiffness along the fiber axis and perpendicular to the fiber axis as well as the Poisson’s ratio

The most common advanced composites are polymer matrix composites consisting of a polymer reinforced by different types of fibers. Fiber reinforced polymer composites consist of strong and stiff fibers embedded in a matrix. Compared with traditional materials, they offer superior durability, light weight, and mechanical properties. Polymer composites are being increasingly used in various applications including aerospace, transportation, industrial and household applications. Like other materials, the selection and design of a polymer composite structure must take

FRP composites having superior material properties when compared with metals, improved corrosion resistance, fatigue resistance, less weight to strength ratio and high fracture toughness. Hence GFRP composites frequently used in several applications like sports goods, racing car bodies and aerospace components [1]. Often composite products manufactured by near-net shapes. The components made by secondary machining processes are involving to get good dimensional accuracy and

In vibration test, notation for complex modulus is suitable for portrayal of dynamic behavior of linear viscoelastic composites. The damping and stiffness which are the constituent part of the complex modulus are belongs to the dynamic mechanical properties, which may be measured with the help of experiments with vibration and wave propagation experiments ,and the measurement of the same is considered for dynamic mechanical analysis.