This article concerns the experimental study of post-impact damage propagation in two thin carbon/epoxy and glass/epoxy hybrid woven composite laminates loaded fatigue tension. Low velocity normal drop weight impact tests are first performed. Post-impact tensile then carried out. They controlled displacement. The is monitored by RX Tomography Digital Image Correlation. influence energy displace...

Board-level solder joint reliability is very critical for handheld electronic products during drop impact. In this study, board-level drop test and finite element method (FEM) are adopted to investigate failure modes and failure mechanisms of lead-free solder joint under drop impact. In order to make all ball grid array (BGA) packages on the same test board subject to the uniform stress and str...

According to the principle and method of drop-weight impact test, the impact resistance of concrete was measured using self-designed U-shape specimens and a newly designed drop-weight impact test apparatus. A series of drop-weight impact tests were carried out with four different masses of drop hammers (0.875, 0.8, 0.675 and 0.5 kg). The test results show that the impact resistance results fail...

The Wafer Level Chip Scale Package (WLCSP) is gaining popularity for its performance and for its ability to meet miniaturization requirements of certain electronic products, especially handheld devices like cell phones. Due to differential bending between the silicon die and the PCB and the large stiffness difference, board level drop/bend tests are widely accepted methods to evaluate damage in...

This paper presents experimental testing of various types concrete under impact loading by using a 2.8-second drop shaft. The shaft is located in the Josef Underground Laboratory and allows dropping projectile from 40 meters that results maximal velocity 100 km/h. Three basic were used framework this study. was normal strength concrete, fibre-reinforced high-performance concrete. slabs construc...

BACKGROUND AND OBJECTIVE Unaccustomed eccentric or eccentric-concentric exercise leaves us stiff and sore the next day and can cause muscle damage. The data about the residual effect of prior eccentric-concentric exercises on oxygen uptake (VO2) during constant cycling exercise in women or the data about differences of such effect between genders are scarce. Therefore, the aim of this study was...

An experimental study was done to determine the diameter and velocity of blood drops falling on a surface by measuring the size of bloodstains they produced and counting the number of radial spines projecting from them. Bloodstains were formed by releasing drops of pig blood with a range of diameters (3.0-4.3 mm) and impact velocities (2.4-4.9 m/s), onto four different flat surfaces (glass, ste...

When a liquid drop impacts a solid surface, air is generally entrapped underneath. Using ultrafast x-ray phase-contrast imaging, we directly visualized the profile of an entrapped air film and its evolution into a bubble during drop impact. We identified a complicated evolution process that consists of three stages: inertial retraction of the air film, contraction of the top air surface into a ...

In epidemic routing for a DTN, it is well-known that message drop degrades the delivery ratio. To minimize the degradation, we need to protect messages with a small number of copies in a DTN. In this paper, we propose a new drop policy which drops a message with the largest expected number of copies first to minimize the impact of message drop.