scholarly journals Determination and monitoring of strength properties of aircraft composite structures by magnetic microwires

2019 ◽  
pp. 37-44
Author(s):  
Miroslav Spodniak ◽  
Jozef Pavlinsky ◽  
Karol Semrad ◽  
Ladislav Fozo ◽  
Jan Savka
Keyword(s):  
Material Properties ◽  
Composite Structures ◽  
Strength Properties ◽  
Practical Application ◽  
Stress Monitoring ◽  
Magnetic Microwires ◽  
Strength Tests ◽  
Prismatic Beam ◽  
The Given ◽  
Composite Samples

The submitted paper deals with the application of magnetic microwires as sensors. The aim is to summarize the engineering view of the given issue and to inform about necessary steps for practical application of such a new sensor in the aircraft industry. The paper talks about the formation of composite samples necessary for tensile strength tests, the aim of which is to obtain material properties of composite materials. The obtained material properties of fiberglass samples are processed into graphical and tabular form. Subsequently, the material properties are used in the strength calculations of the prismatic beam, in which magnetic microwires are applied in the experimental part of the work. There are described in the submitted article two application of magnetic microwires as a stress monitoring sensors.

Influence of Sample Preparation on Intrinsic Stress Inside a Model Chip—Comparison of Results from Electric Read-Out and Raman Spectroscopy

2017 ◽  
Author(s):  
T. Schaffus ◽  
H. Pfaff ◽  
P. Albert ◽  
M. Schaffus ◽  
F. Kroninger ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Sample Preparation ◽  
Intrinsic Stress ◽  
Stress Monitoring ◽  
Preparation Methods ◽  
Comparison Of Results ◽  
The Given

Abstract The given project is to benchmark typical preparation methods under the aspect of the influence of initial intrinsic stresses inside electric components. Raman spectroscopy has been applied as well as the piezo resistive readout on a specifically designed model stress monitoring chip.

Integrally-Stiffened Composite Damage Tolerance Evaluated by Computational Simulation

2001 ◽  
Author(s):  
Christos C. Chamis ◽  
Levon Minnetyan
Keyword(s):  
Material Properties ◽  
Composite Structures ◽  
Failure Modes ◽  
Damage Tolerance ◽  
Epoxy Composite ◽  
Computational Simulation ◽  
Computer Code ◽  
Simulation Design ◽  
Damage Initiation ◽  
Composite Damage

Abstract An integrally stiffened graphite/epoxy composite rotorcraft structure is evaluated via computational simulation. A computer code that scales up constituent micromechanics level material properties to the structure level and accounts for all possible failure modes is used for the simulation of composite degradation under loading. Damage initiation, growth, accumulation, and propagation to fracture are included in the simulation. Design implications with regard to defect and damage tolerance of integrally stiffened composite structures are examined. A procedure is outlined regarding the use of this type of information for setting quality acceptance criteria, design allowables, damage tolerance, and retirement-for-cause criteria.

Maximizing the Fundamental Natural Frequency of Triangular Composite Plates

1996 ◽  
Vol 118 (2) ◽  
pp. 141-146 ◽  
Author(s):  
S. Abrate
Keyword(s):  
Natural Frequency ◽  
Material Properties ◽  
Composite Structures ◽  
Natural Frequencies ◽  
Ritz Method ◽  
Laminated Composite ◽  
Composite Plates ◽  
Mode Shapes ◽  
Fundamental Natural Frequency ◽  
Wide Range

While many advances were made in the analysis of composite structures, it is generally recognized that the design of composite structures must be studied further in order to take full advantage of the mechanical properties of these materials. This study is concerned with maximizing the fundamental natural frequency of triangular, symmetrically laminated composite plates. The natural frequencies and mode shapes of composite plates of general triangular planform are determined using the Rayleigh-Ritz method. The plate constitutive equations are written in terms of stiffness invariants and nondimensional lamination parameters. Point supports are introduced in the formulation using the method of Lagrange multipliers. This formulation allows studying the free vibration of a wide range of triangular composite plates with any support condition along the edges and point supports. The boundary conditions are enforced at a number of points along the boundary. The effects of geometry, material properties and lamination on the natural frequencies of the plate are investigated. With this stiffness invariant formulation, the effects of lamination are described by a finite number of parameters regardless of the number of plies in the laminate. We then determine the lay-up that will maximize the fundamental natural frequency of the plate. It is shown that the optimum design is relatively insensitive to the material properties for the commonly used material systems. Results are presented for several cases.

Correlation between the mineral composition and strength properties of sulfate rocks

2021 ◽  
pp. qjegh2020-173
Author(s):  
Mohammad Reza Rahimi ◽  
Seyed Davoud Mohammadi ◽  
Alireza Taleb Beydokhti
Keyword(s):  
Mineral Composition ◽  
Failure Mode ◽  
Strength Properties ◽  
Shear Mode ◽  
Rock Cores ◽  
Strength Tests ◽  
Engineering Problems ◽  
Gypsum Rock ◽  
Under Construction ◽  
First Time

The literature review confirms that the effect of mineral composition on the strength properties of rocks has rarely been studied. One of the most problematic sedimentary rocks is sulfate rocks, which cause engineering problems in the infrastructure sites such as reservoir dams. In this paper, for the first time, the effect of mineral composition on the strength properties of sulfate rocks was investigated. The rock blocks were collected from the Gachsaran Formation outcrops at the four under construction reservoir dam sits in Iran. After preparing, drying and saturation the rock cores samples (329 samples), uniaxial compressive strength tests were performed in accordance with ASTM and ISRM standards. The results of this study confirmed that firstly, there is a correlation between the mineral composition and the strength properties of the sulfate rocks, but the obtained relationships do not have the necessary certainty to be used as predictive equations. Secondly, by increasing the amount of anhydrite or microcrystalline carbonates in a gypsum rock, its strength properties are increased. Thirdly, in a dry condition the dominant failure mode in gypsum and anhydrite rocks is a shear and dilatation mode, respectively, but after saturation, the failure mode tends to shear mode.

scholarly journals Shrinkage and Strength Properties of Coal Gangue Ceramsite Lightweight Aggregate Concrete

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yunsen Wang ◽  
Jingping Qiu ◽  
Chao Zeng
Keyword(s):  
Waste Treatment ◽  
Concrete Strength ◽  
Lightweight Aggregate ◽  
Strength Properties ◽  
Coal Gangue ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Concrete Shrinkage ◽  
Strength Tests ◽  
The Stability

It is a promising and effective method for waste treatment by using coal gangue to make lightweight aggregate concrete. However, lightweight aggregate concrete with low-density coal gangue ceramsite is prone to cracking during volume shrinkage, which limits its application in the construction industry. In an attempt to resolve the problem of cracking in shrinkage, this study investigated the effect of prewetting time and shrinkage reducing agents on shrinkage volume and concrete strength through a series of concrete shrinkage and strength tests. The experimental results show that shrinkage volume reduced at a prewetting time of 12 hrs or with a 2% addition of D-230 polyether amine reductant. With the optimal conditions of 12 hrs prewetting time and 2% addition of the reductant, the concrete shrinkage volume significantly decreased with a negligible impact on its strength. Appropriate amount of shrinkage reducing agent and adjustment of prewetting time of coal gangue ceramsite are necessary to reduce the shrinkage rate and improve the stability of the specimen. This is of great significance to wide application of lightweight aggregate concrete with coal gangue ceramsite.

Review of material test standardization status for the material qualification of laminated thermosetting composite structures

2020 ◽  
pp. 073168442095810
Author(s):  
Sang Yoon Park ◽  
Won Jong Choi
Keyword(s):  
Composite Materials ◽  
Material Properties ◽  
Composite Structures ◽  
Failure Modes ◽  
Laminated Composite ◽  
Test Methods ◽  
Test Method ◽  
Experimental Comparison ◽  
Laminated Composite Materials ◽  
Design Values

This paper presents a review of recent literature related to the static mechanical testing of thermoset-based carbon fiber reinforced composites and introduces a material qualification methodology to generate statistically-based allowable design values for aerospace application. Although most test methods have been found to be effective in determining the specific material properties by incorporating them into the material qualification and quality control provisions, a full validation to clarify the behavior of thermoset-based laminated composite materials is currently lacking, particularly with regard to the characterization of compressive, in-plane, interlaminar shear, and damage tolerance properties. The present study obtains information on the different types of test method that can be employed within the same material properties, and makes an in-depth experimental comparison based on the past literatures. A discussion on the scope of theoretical analysis involves a description of how the proposed test method can be adequate for obtaining more accurate material properties. This discussion is directly applicable to the assessment of material nonlinearity and the geometrical effect of specimens. Finally, the resulting failure modes and the effect of each material property are studied to aid the understanding of the load distribution and behavior of laminated composite materials.

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