Evaluation of the measurement uncertainty of the stiffness modulus: test case of indirect tensile on cylindrical specimens

This study treats the measurement uncertainties that we can find in the stiffness modulus of the bituminous test. We present all the sensors installed on rigidity modulus measurement chains and also their uncertainty ranges. Several parameters influence the rigidity module's value, such as the parameters related to experimental conditions, and others are rather connected to the equipment's specification, which are the speed, the loading level, the temperature, the tested sample dimension, and the data acquisition, etc. All these factors have a great influence on the value of the modulus of rigidity. To qualify the uncertainty factors, we used two approaches: the first one is made by following the method described by the GUM (Guide to the expression of uncertainty in measurement), the second approach based on the numerical simulation of the Monte Carlo. The two results are then compared for an interval of confidence of 95%. The paper also shows the employment of the basic methods of statistical analysis, such as the Comparing of two variances. Essential concepts in measurement uncertainty have been compiled and the determination of the stiffness module parameters are discussed. It has been demonstrated that the biggest source of error in the stiffness modulus measuring process is the repeatability has a contribution of around 45.23%

Evaluation of the measurement uncertainty of the stiffness modulus: test case of indirect tensile on cylindrical specimens

This study treats the measurement uncertainties that we can find in the stiffness modulus of the bituminous test. We present all the sensors installed on rigidity modulus measurement chains and also their uncertainty ranges. Several parameters influence the rigidity module's value, such as the parameters related to experimental conditions, and others are rather connected to the equipment's specification, which are the speed, the loading level, the temperature, the tested sample dimension, and the data acquisition, etc. All these factors have a great influence on the value of the modulus of rigidity. To qualify the uncertainty factors, we used two approaches: the first one is made by following the method described by the GUM (Guide to the expression of uncertainty in measurement), the second approach based on the numerical simulation of the Monte Carlo. The two results are then compared for an interval of confidence of 95%. The paper also shows the employment of the basic methods of statistical analysis, such as the Comparing of two variances. Essential concepts in measurement uncertainty have been compiled and the determination of the stiffness module parameters are discussed. It has been demonstrated that the biggest source of error in the stiffness modulus measuring process is the repeatability has a contribution of around 45.23%

Comparative study on the successive impact behavior of composites in ship structures

Composite materials are categorized to be highly sensitive to low-velocity impact events. This feature is considered as a serious limitation for their application in engineering. Therefore, understanding impact energy absorption is critical in improving composite material damage tolerance and especially under successive impacts. This work was dedicated to an experimental investigation that aims to study and compare the energy absorption ability and damage behavior of PVC-foam sandwich and GFRP laminated composites under multiple impacts occurring at small energy levels. For this purpose, low-velocity impact repeated tests were carried out until total absorption of the impact initial energy was reached. A relative energy absorption index and a rebound index were proposed in order to assess energy absorption capacity. The results indicated that, directly after the first impact, the sandwich composite formed from two 4mm laminated skins absorbed 80% of the initial impact energy, in comparison to approximately 60% for 8mm laminated composite. This performance of sandwich composite is attributed to the damping ability of the core. Also, the impact velocity rebound rate of this composite was found to be higher than that of laminates. However, impact damage is greater in composite sandwiches than in laminates