Dynamic Behavior of Materials

Tensile Behavior of Kevlar 49 Woven Fabrics over a Wide Range of Strain Rates (Dynamic Behavior of Materials)

ABSTRACT Kevlar and other ballistic fabrics are frequently used in dynamic loading applications such as personnel protective equipment (armor) and soft engine containment systems for fan blade out events in aircraft engines. Numerical simulations of these events require constitutive models that are based on mechanical experiments that approximate the load conditions present in the application. […]

The Effect of Loading Rate on the Tensile Behavior of Single Zylon Fiber (Dynamic Behavior of Materials)

ABSTRACT The commercially available Zylon™ single fiber has been investigated to understand the effect of strain rate on the tensile response. Experiments were conducted on single Zylon fibers across a range of strain rates ranging from 0.001/s to ~1000/s. The low rate uniaxial tensile experiments were performed using a Bose TestBench™ system. The high rate […]

Statistical analysis of fiber gripping effects on Kolsky bar test (Dynamic Behavior of Materials)

ABSTRACT Preliminary data for testing fibers at high strain rates using the Kolsky bar test by Ming Cheng et al. [1] indicated minimal effect of strain rate on the tensile stress-strain behavior of PPTA [poly (p-phenylene terephathalamide)] fibers. In a different study, Lim et al. [2] reported that the tensile strengths of the copolymer aramid […]

Perpendicular Yarn Pull-out Behavior under Dynamic Loading (Dynamic Behavior of Materials)

ABSTRACT Multi-layers of woven fabric, characterized by high strength, high flexibility and low density, have been widely used for protective systems, from bulletproof vests to turbine engine fragment barriers. Under ballistic impact, the kinetic energy of the projectile is absorbed by the fabrics deforming largely in out-of- plane direction, which retards the motion of the […]

Dynamic Response of Homogeneous and Functionally Graded Foams When Subjected to Transient Loading by a Square Punch (Dynamic Behavior of Materials)

Abstract In this work, failure response of structural syntactic foams subjected to dynamic square punch impact loading is studied. Experiments are being carried out on homogeneous and compositionally graded syntactic foam sheets. The former are made of hollow microballoons dispersed uniformly in an epoxy matrix at different volume fractions whereas in the latter the volume […]

Dynamic Strain Measurement of Welded Tensile Specimens Using Digital Image Correlation (Dynamic Behavior of Materials)

Abstract The high strain rate behavior of a welded interface was evaluated using a direct tension Kolsky (Hopkinson) bar setup. The weld and the Heat Affected Zone (HAZ) were included in the gage section of the tensile specimen to evaluate the effects of structural constraint (vs. weld metal only). The welds of interest are under-matched […]

Ultra high speed full-field strain measurements on spalling tests on concrete materials (Dynamic Behavior of Materials) Part 1

ABSTRACT This paper presents the use of an ultra high speed camera in conjunction with full-field measurements (grid method) to measure strain fields in a concrete specimen submitted to a spalling test (inertial tensile test). A Shimadzu camera is used to capture the images with a time resolution of 2 microseconds. Strain and acceleration fields […]

Ultra high speed full-field strain measurements on spalling tests on concrete materials (Dynamic Behavior of Materials) Part 2

Identification procedure with the Virtual Fields Method The Virtual Fields Method (VFM) is a well known procedure to identify materials mechanical constitutive parameters using full field measurement [12] and has been applied to many different problems over the years. The VFM is based on the principle of virtual work which, in the case of small […]

Contact Mechanics of Impacting Slender Rods: Measurement and Analysis (Dynamic Behavior of Materials)

ABSTRACT To validate models of contact mechanics in low speed structural impact, slender rods with curved tips were impacted in a drop tower, and measurements of the contact and vibration were compared to analytical and finite element (FE) models. The contact area was recorded using a thin-film transfer technique, and the contact duration was measured […]

Solenoid Actuated, Rail Mounted, Aircraft Payload Release Mechanisms (Dynamic Behavior of Materials) Part 1

ABSTRACT The spring loaded detent mechanisms currently used to retain missile-type payloads require a high forward load in order to overcome a spring before release can be achieved. However for smaller aircraft, such as UAVs, there is a pressing need to develop alternate mechanisms which require reduced release forces to avoid excessively loading the vehicle. […]

← Previous Entries

Next Entries →