scholarly journals Experimental Snap Loading of Synthetic Ropes

2005 ◽  
Vol 12 (3) ◽  
pp. 163-175 ◽  
Author(s):  
C.M. Hennessey ◽  
N.J. Pearson ◽  
R.H. Plaut
Keyword(s):  
Mathematical Model ◽  
Drop Tower ◽  
Drop Height ◽  
Dynamic Tests ◽  
Drop Weight ◽  
Tensile Forces ◽  
Drop Tests ◽  
Height Drop

Large tensile forces, known as snap loads, can occur when a slack rope becomes taut. Such forces may damage the rope or masses connected to it. Experiments are described in which one end of a rope is attached to the top of a drop tower and the bottom end is attached to a weight. The weight is raised to a certain height and then released. The force at the top of the rope and the acceleration of the weight are recorded during the first snap load that occurs. Repeated drop tests are performed on each rope. The effects of the type of rope, drop height, drop weight, whether the rope has been subjected to static precycling, and the number of previous dynamic tests are examined. A mathematical model is proposed for the rope force as a function of the displacement and velocity of the weight.

Effects of Lumbar Spine Assemblies and Body-Borne Equipment Mass on Anthropomorphic Test Device Responses During Drop Tests

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Daniel Aggromito ◽  
Mark Jaffrey ◽  
Allen Chhor ◽  
Bernard Chen ◽  
Wenyi Yan
Keyword(s):  
Lumbar Spine ◽  
Federal Aviation Administration ◽  
Relative Displacement ◽  
Drop Tower ◽  
Test Device ◽  
Hybrid Iii ◽  
Drop Tests ◽  
Occupant Injury ◽  
Maximum Relative Displacement ◽  
The Impact

When simulating or conducting land mine blast tests on armored vehicles to assess potential occupant injury, the preference is to use the Hybrid III anthropomorphic test device (ATD). In land blast events, neither the effect of body-borne equipment (BBE) on the ATD response nor the dynamic response index (DRI) is well understood. An experimental study was carried out using a drop tower test rig, with a rigid seat mounted on a carriage table undergoing average accelerations of 161 g and 232 g over 3 ms. A key aspect of the work looked at the various lumbar spine assemblies available for a Hybrid III ATD. These can result in different load cell orientations for the ATD which in turn can affect the load measurement in the vertical and horizontal planes. Thirty-two tests were carried out using two BBE mass conditions and three variations of ATDs. The latter were the Hybrid III with the curved (conventional) spine, the Hybrid III with the pedestrian (straight) spine, and the Federal Aviation Administration (FAA) Hybrid III which also has a straight spine. The results showed that the straight lumbar spine assemblies produced similar ATD responses in drop tower tests using a rigid seat. In contrast, the curved lumbar spine assembly generated a lower pelvis acceleration and a higher lumbar load than the straight lumbar spine assemblies. The maximum relative displacement of the lumbar spine occurred after the peak loading event, suggesting that the DRI is not suitable for assessing injury when the impact duration is short and an ATD is seated on a rigid seat on a drop tower. The peak vertical lumbar loads did not change with increasing BBE mass because the equipment mass effects did not become a factor during the peak loading event.

scholarly journals Mathematical model of the modified tissue deformation under stretching

2021 ◽  
Vol 274 ◽  
pp. 11005
Author(s):  
Rashit Kayumov ◽  
Inzilija Mukhamedova
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Strain State ◽  
Mechanical Characteristics ◽  
Acceptable Accuracy ◽  
Synthetic Materials ◽  
Tensile Forces ◽  
Theory Of Mixtures ◽  
Stiffness Characteristics

One of the effective methods for modifying natural and synthetic materials is a use of the flocking process. To analyze a quality of the modified fabrics, it is useful to have mathematical models describing a stress-strain state of the fabrics when exposed to various loads. A method has been developed for determining the stiffness characteristics of a flocked fabric based on the results of testing samples cut at different angles to the base at different tensile forces. This technique makes it possible to analyze the effect of flocking on the mechanical characteristics of the fabric. It was revealed that the theory of mixtures, when averaging the properties of the fabrics and glue with respect to thickness, does not allow determining the stiffness characteristics with acceptable accuracy. The limits of applicability of the theory of mixtures were determined when carrying out averaging of the mechanical characteristics with respect to the area of the flocked fabrics.

scholarly journals Study on the drop impact characteristics and impact damage mechanism of sweet potato tubers during harvest

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255856
Author(s):  
Guocheng Bao ◽  
Gongpu Wang ◽  
Bing Wang ◽  
Lianglong Hu ◽  
Xiaowei Xu ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Sweet Potato ◽  
Damage Mechanism ◽  
Drop Height ◽  
Potato Tubers ◽  
Impact Stress ◽  
Chunk Size ◽  
The Impact ◽  
Damage Impact ◽  
Critical Damage

Collision of falling in the mechanical harvesting process of sweet potato is one of the main causes of epidermal destruction and damage to sweet potato tubers. Therefore, a sweet potato mechanical characteristic test and a full-factor sweet potato drop test were designed. Based on the analysis of the fitting mathematical model, the impact of the drop height, collision material and sweet potato chunk size on the damage of the sweet potato were studied. The mathematical models were established by fitting analysis of the IBM SPSS Statistics 22 software between the drop height and the sweet potato chunk size with each test index (impact force, impact stress, broken skin area and damaged area). The critical epidermal destruction height and the critical damage height of a certain size of sweet potato when it collides with a collision material can be calculated by the mathematical model, and the critical epidermal destruction mass and critical damage mass of sweet potato when it falls from a certain height and collides with a collision material can also be calculated. Then a series of critical values (including critical epidermal destruction force value, critical epidermal destruction impact stress, critical damage force value, critical damage impact stress) of mechanical properties of sweet potato were obtained. The results show that the impact deformation of sweet potato includes both elastic and plastic ones, and has similar stress relaxation characteristics. The critical damage impact stress of sweet potato is that the average value of the impact stress on the contact surface is less than it’s Firmness. The results provided a theoretical basis for understanding the collision damage mechanism of sweet potato and how to reduce the damage during harvest.

scholarly journals Theoretical-experimental static and dynamic analysis of double layered catenary

2010 ◽  
Vol 8 (2) ◽  
pp. 169-175 ◽  
Author(s):  
Ljubomir Vlajic ◽  
Dragan Kostic
Keyword(s):  
Mathematical Model ◽  
Tensile Force ◽  
Cost Effective ◽  
Calculation Model ◽  
Dynamic Tests ◽  
Building Roof ◽  
Static And Dynamic Analysis ◽  
Static And Dynamic Tests ◽  
The Stability ◽  
The Mathematical Model

The paper presents the results of static and dynamic tests of double layered catenary of the swimming pool building roof in Leskovac. By the comparison of measured and calculated values, a potential was created to correct the mathematical model, and to verify it. Only then, the calculation model for all sorts of static and dynamic load was able to simulate the realistic behavior of the structure. In this paper, the authors presented the basic recommendations in terms of what initial tensile force should be adopted in order to control the stability of such very cost-effective girders.

Mathematical model for soluble carbonaceous substrate biosorption

1995 ◽  
Vol 31 (2) ◽  
pp. 67-77 ◽  
Author(s):  
Libor Novák ◽  
Luis Larrea ◽  
Jiri Wanner
Keyword(s):  
Mathematical Model ◽  
Activated Sludge ◽  
Treatment Plant ◽  
Synthetic Wastewater ◽  
Dynamic Tests ◽  
Cultivation Conditions ◽  
Biokinetic Model ◽  
Kinetic Tests ◽  
Conventional Models ◽  
Adsorption Desorption

An activated sludge mathematical model for soluble carbonaceous substrate biosorption has been developed. The model allows the soluble COD fractions in biological reactors of a wastewater treatment plant and/or in batch cultivations to be predicted more precisely than by using conventional models. Special attention was paid to interactions between the biokinetic model structure and population dynamics of microorganisms in activated sludge. The model was developed using observations made on a synthetic wastewater which was dosed to a lab-scale, continuously operated plant with the D-R-D-N configuration. The development of the model advanced through several biokinetic models which resulted in a final version of the biosorption model. The model is constructed on a matrix structure. Adsorption, desorption and hydrolysis kinetics are incorporated into the model. Experimental results from batch cultivations carried out under anoxic and oxic conditions as well as some dynamic tests carried out with the continuously operated system served for the model calibration. Simulations of a wide diversity of kinetic tests demonstrate that the model is able to accurately predict the soluble COD under different cultivation conditions.

Predicted Response of the Die-Carrier Assembly in Flexible Electronics to the Combined Action of Tension and Bending Applied to the Carrier

2011 ◽  
Vol 79 (1) ◽  
Author(s):  
E. Suhir
Keyword(s):  
Mathematical Model ◽  
Normal Stress ◽  
Cross Sections ◽  
Flexible Electronics ◽  
Bending Moments ◽  
Analysis And Design ◽  
Tensile Forces ◽  
Combined Action ◽  
The Cross

A die-carrier assembly, subjected to the external tensile forces and bending moments applied to the flexible carrier is considered. The objective of the analysis is to develop a simple, easy-to-use, and physically meaningful predictive analytical (“mathematical”) model aimed at understanding the physics of the combined action of tension and bending experienced by the carrier and transmitted to the die through the more-or-less compliant bond. The addressed stresses include the interfacial shearing and peeling stresses, as well as the normal stress acting in the cross sections of the die. The obtained formulae can be used in the analysis and design of assemblies of the type in question.

scholarly journals A Hot Spots Ignition Probability Model for Low-Velocity Impacted Explosive Particles Based on the Particle Size and Distribution

2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Hong-fu Guo ◽  
Yan-qing Wu ◽  
Feng-lei Huang
Keyword(s):  
Particle Size ◽  
Probability Model ◽  
Quadratic Function ◽  
Drop Height ◽  
Low Velocity ◽  
Contact Zones ◽  
Ignition Probability ◽  
Drop Weight ◽  
Mean Size ◽  
Size Of Particles

Particle size and distribution play an important role in ignition. The size and distribution of the cyclotetramethylene tetranitramine (HMX) particles were investigated by Laser Particle Size Analyzer Malvern MS2000 before experiment and calculation. The mean size of particles is 161 μm. Minimum and maximum sizes are 80 μm and 263 μm, respectively. The distribution function is like a quadratic function. Based on the distribution of micron scale explosive particles, a microscopic model is established to describe the process of ignition of HMX particles under drop weight. Both temperature of contact zones and ignition probability of powder explosive can be predicted. The calculated results show that the temperature of the contact zones between the particles and the drop weight surface increases faster and higher than that of the contact zones between two neighboring particles. For HMX particles, with all other conditions being kept constant, if the drop height is less than 0.1 m, ignition probability will be close to 0. When the drop heights are 0.2 m and 0.3 m, the ignition probability is 0.27 and 0.64, respectively, whereas when the drop height is more than 0.4 m, ignition probability will be close to 0.82. In comparison with experimental results, the two curves are reasonably close to each other, which indicates our model has a certain degree of rationality.

The Fracture of Reinforced Concrete under Impact Loading

1985 ◽  
Vol 64 ◽  
Author(s):  
Arnon Bentur ◽  
Sidney Mindess ◽  
N. Banthia
Keyword(s):  
Reinforced Concrete ◽  
Impact Loading ◽  
Concrete Beams ◽  
Steel Reinforcement ◽  
Drop Height ◽  
Reinforcing Bars ◽  
Drop Weight ◽  
Weight Impact ◽  
Concrete Matrix

ABSTRACTThe behaviour under impact loading of concrete beams, reinforced with both smooth and deformed steel reinforcing bars, was studied. Tests were carried out using an instrumented drop-weight impact apparatus, with a 345 kg mass hammer, and drop heights of up to 2.36 m. It was found that, under certain circumstances, the steel reinforcement itself fractured. This behaviour is discussed with reference to the drop height, the type of reinforcement, and the strength of the concrete matrix.

Sign in / Sign up

Export Citation Format

Share Document