scholarly journals Shock Attenuation of Intervertebral Disc Following Fatigue Loading

2011 ◽  
Vol 27 (1) ◽  
pp. 9-17 ◽  
Author(s):  
C.-K. Chiang ◽  
C.-L. Yang ◽  
W.-C. Chen ◽  
C.-H. Chang ◽  
S.-C. Huang ◽  
...  
Keyword(s):  
Impact Energy ◽  
Fatigue Loading ◽  
Phase Delay ◽  
Contact Period ◽  
Shock Attenuation ◽  
Spinal Motion ◽  
Risk Of Injury ◽  
Motion Segment ◽  
Force Transmissibility ◽  
The Impact

ABSTRACTShock absorption is one of the fundamental biomechanical functions of disc. The knowledge of the effect of fatigue loading, impact energy and contact period on the disc shock attenuation is important in clarifying the risk factors of back pain and evaluating the efficacy of novel disc prosthesis. The purpose of this study is to find the changes of shock attenuation of motion segment after fatigue loading, and the effect of impact energy and contact period on the disc shock attenuation pre and post fatigue loading.The 3-unit porcine spinal motion segment was used for testing. The impact test was applied pre and post fatigue loading. Impact energy and contact period were controlled in the experiment. Shock attenuation properties, including the acceleration attenuation (AA) of disc, force transmissibility (FT) and phase delay of force (PDF) of motion segment, were calculated from the acceleration and force responses.The results showed that the shock attenuation properties (acceleration attenuation and force transmissibility) decreased post fatigue. The disc acceleration attenuation was independent of impact energy and contact period. The disc acceleration attenuation was 0.78 (−1.06dB) pre fatigue and 1.04 (0.14dB) post fatigue. The force transmissibility of motion segment decreased post fatigue only during short contact period. The phase delay of force did not change significantly post fatigue.We found that the fatigue loading decreased the disc shock attenuation. The disc was at higher risk of injury following fatigue loading even at a mild impact loading. The disc acceleration attenuation was invariant of impact energy and contact period, but decreased post fatigue. The disc acceleration attenuation is a good index to evaluate the degree of fatigue injury.

The Load Sharing Contribution of Spinal Facet Joint During Impact Loading: A Porcine Biomechanical Model

2003 ◽  
Author(s):  
Cheng-Chuan Lai ◽  
Jaw-Lin Wang ◽  
Guan-Liang Chang ◽  
Cheng-Hsien Chung
Keyword(s):  
Impact Energy ◽  
Impact Loading ◽  
Facet Joint ◽  
Biomechanical Model ◽  
Load Sharing ◽  
Loading Conditions ◽  
Vertical Loading ◽  
Motion Segment ◽  
The Impact

The components that share the loading of motion segment include the facet joint and disc. Nachemson [1] reported the facet joint share 18% of vertical loading in a motion segment; while many other researchers reported the load sharing percentage of facet joint ranges from 1% to 57% [2,3]. The current study developed a unique apparatus using an in vitro porcine spine model to quantify the alteration of loading in the facet joint under impact compressive loading at different loading conditions. A drop tower type impact apparatus was used to produce the impact energy for the motion segment. A 6-D load cell was placed under the specimen to detect the force and moment responses. The pressure sensor was inserted into the facet joint to find the contact force. The pointed axial compresive forces were applied at 8 locations from anterior to posterior of upper vertebrae to mimic different impact loading conditions. The impact energy was fixed at 1.2 J. We found that; when the loading was applied anteriorly, the facet joint sustained very small percentages of the loading; while the location of the loading moved posteriorly, the facet joint sharing percentages increased. The largest sharing percentages of facet joint reached 30% in the current study.

Energy Criterion in the Assessment of Damping of a Spinal Motion Segment Subjected to Cyclic Loading

2015 ◽  
Vol 240 ◽  
pp. 261-265 ◽  
Author(s):  
Małgorzata Żak ◽  
Celina Pezowicz
Keyword(s):  
Energy Dissipation ◽  
Cyclic Loading ◽  
Intervertebral Disc ◽  
Spinal Column ◽  
Energy Criterion ◽  
Spinal Motion ◽  
Motion Segment ◽  
The Impact ◽  
Spinal Motion Segment

The primary functions of the spine, and in particular the intervertebral disc, are to support transfer of loads, permit motion, and dissipate energy in the spine. The objective of this study was to analyse changes in damping of a spinal motion segment subjected to cyclic loading using the energy criterion. Another important aspect of the undertaken study was an evaluation of the impact of posterior spinal column elements, i.e. articular processes joints on changes in energy dissipation by the intervertebral disc.

Experimental Research on CFRP Laminates with Different Impact Energy Levels

2014 ◽  
Vol 1030-1032 ◽  
pp. 1060-1063
Author(s):  
A Ying Zhang ◽  
Dong Xing Zhang
Keyword(s):  
Crack Length ◽  
Impact Energy ◽  
Impact Damage ◽  
Energy Levels ◽  
Three Dimensional ◽  
Fatigue Loading ◽  
Crater Depth ◽  
Cfrp Laminates ◽  
65 J ◽  
The Impact

The effects of thickness and impact energy on the impact damage of CFRP laminates were studied in this paper. Impact tests for the CFRP laminates with the size of 600 mm×700 mm with five different thicknesses were subjected to impact fatigue loading at different energy levels from 5 J to 65 J. The crater depth and matrix length were investigated according to different energy levels and different thicknesses. The impact damage was evaluated by visual inspection, three-dimensional microscope. The experimental results reveal that the crater depth and the crack length increase with the increasing impact energy. For the same impact energy, the crater depth and the crack length decreased with the increasing thickness of specimens.

Response and failure modes of biaxial warp-knitted flexible composite subject to low-velocity impact

2021 ◽  
pp. 152808372110154
Author(s):  
Ziyu Zhao ◽  
Tianming Liu ◽  
Pibo Ma
Keyword(s):  
Impact Energy ◽  
Linear Density ◽  
Failure Modes ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Minor Effect ◽  
Low Velocity ◽  
Velocity Impact ◽  
Flexible Composites ◽  
The Impact

In this paper, biaxial warp-knitted fabrics were produced with different high tenacity polyester linear density and inserted yarns density. The low-velocity impact property of flexible composites made of polyurethane as matrix and biaxial warp-knitted fabric as reinforcement has been investigated. The effect of impactor shape and initial impact energy on the impact response of flexible composite is tested. The results show that the initial impact energy have minor effect on the impact response of the biaxial warp-knitted flexible composites. The impact resistance of flexible composite specimen increases with the increase of high tenacity polyester linear density and inserted yarns density. The damage morphology of flexible composite materials is completely different under different impactor shapes. The findings have theoretical and practical significance for the applications of biaxial warp-knitted flexible composite.

scholarly journals Impact resistance of steel materials to ballistic ejecta and shelter development using steel deck plates

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Hiroyuki Yamada ◽  
Kohei Tateyama ◽  
Shino Naruke ◽  
Hisashi Sasaki ◽  
Shinichi Torigata ◽  
...  
Keyword(s):  
Impact Energy ◽  
Impact Test ◽  
Impact Resistance ◽  
Protective Layer ◽  
High Strength ◽  
Steel Plates ◽  
Corrugated Plates ◽  
Shelter Construction ◽  
The Impact ◽  
Ballistic Ejecta

AbstractThe destruction caused by ballistic ejecta from the phreatic eruptions of Mt. Ontake in 2014 and Mt. Kusatsu-Shirane (Mt. Moto-Shirane) in 2018 in Japan, which resulted in numerous casualties, highlighted the need for better evacuation facilities. In response, some mountain huts were reinforced with aramid fabric to convert them into shelters. However, a number of decisions must be made when working to increase the number of shelters, which depend on the location where they are to be built. In this study, we propose a method of using high-strength steel to reinforce wooden buildings for use as shelters. More specifically, assuming that ballistic ejecta has an impact energy of 9 kJ or more, as in previous studies, we developed a method that utilizes SUS304 and SS400 unprocessed steel plates based on existing impact test data. We found that SUS304 is particularly suitable for use as a reinforcing material because it has excellent impact energy absorption characteristics due to its high ductility as well as excellent corrosion resistance. With the aim of increasing the structural strength of steel shelters, we also conducted an impact test on a shelter fabricated from SS400 deck plates (i.e., steel with improved flexural strength provided by work-hardened trapezoidal corrugated plates). The results show that the shelter could withstand impact with an energy of 13.5 kJ (2.66 kg of simulated ballistic ejecta at 101 m/s on impact). In addition, from the result of the impact test using the roof-simulating structure, it was confirmed the impact absorption energy is further increased when artificial pumice as an additional protective layer is installed on this structure. Observations of the shelter after the impact test show that there is still some allowance for deformation caused by projectile impact, which means that the proposed steel shelter holds promise, not only structurally, but also from the aspects of transportation and assembly. Hence, the usefulness of shelters that use steel was shown experimentally. However, shelter construction should be suitable for the target environment.

Will We Lose If We Lose You? Players’ Absence, Teams’ Performance and the Overlapping of Competitions

2021 ◽  
pp. 152700252110084
Author(s):  
Levi Pérez
Keyword(s):  
Negative Impact ◽  
Potential Cost ◽  
Psychological Momentum ◽  
Risk Of Injury ◽  
European Football ◽  
The Impact

It is common for elite players to represent their respective countries in international competitions. However, there is a potential cost to the club team derived from that situation (risk of injury, fatigue, psychological momentum, etc.). This paper evaluates the impact of players’ absence on European football teams’ performance by focusing on the Africa Cup of Nations as the case study. The results indicate that the sending of players to the African tournament has a relatively small negative impact on teams’ performance. But this cannot be generalized to all the leagues and loses significance when corrected by players’ abilities.

scholarly journals Microstructure and Mechanical Properties of Heat-Affected Zone of Repeated Welding AISI 304N Austenitic Stainless Steel by Gleeble Simulator

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 773
Author(s):  
Y.H. Guo ◽  
Li Lin ◽  
Donghui Zhang ◽  
Lili Liu ◽  
M.K. Lei
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Impact Energy ◽  
Heat Affected Zone ◽  
Ferrite Content ◽  
Equipment Safety ◽  
Microstructure And Mechanical Properties ◽  
Δ Ferrite ◽  
The Impact

Heat-affected zone (HAZ) of welding joints critical to the equipment safety service are commonly repeatedly welded in industries. Thus, the effects of repeated welding up to six times on the microstructure and mechanical properties of HAZ for AISI 304N austenitic stainless steel specimens were investigated by a Gleeble simulator. The temperature field of HAZ was measured by in situ thermocouples. The as-welded and one to five times repeated welding were assigned as-welded (AW) and repeated welding 1–5 times (RW1–RW5), respectively. The austenitic matrices with the δ-ferrite were observed in all specimens by the metallography. The δ-ferrite content was also determined using magnetic and metallography methods. The δ-ferrite had a lathy structure with a content of 0.69–3.13 vol.%. The austenitic grains were equiaxial with an average size of 41.4–47.3 μm. The ultimate tensile strength (UTS) and yield strength (YS) mainly depended on the δ-ferrite content; otherwise, the impact energy mainly depended on both the austenitic grain size and the δ-ferrite content. The UTS of the RW1–RW3 specimens was above 550 MPa following the American Society of Mechanical Engineers (ASME) standard. The impact energy of all specimens was higher than that in ASME standard at about 56 J. The repeated welding up to three times could still meet the requirements for strength and toughness of welding specifications.

The Investigation in the Influence of Hardness to Transition Point after Tempering for Boric Carbon Steels

2013 ◽  
Vol 690-693 ◽  
pp. 186-192
Author(s):  
Ho Hua Chung ◽  
Tsong Hsin Chen
Keyword(s):  
Impact Energy ◽  
Carbon Steels ◽  
Material Strength ◽  
Tempering Temperature ◽  
Material Test ◽  
Wire Material ◽  
Steel Material ◽  
The Wire ◽  
The Impact ◽  
Test Fragment

This study concerned the influence of the material strength, ductility and impact energy and the relationship of the broken section profile vs. ductile transition brittle where the steel material was treated under different tempering temperature and hardness. Generally after the steel materials, 10B35 coil wire materials which was generally applied to form screws, was treated by quenching and tempering, its hardness ranged from HRC30 to HRC45. The results showed that the elongation rate beyond 20.4% would be proportional to the impact energy with linear relation, but with reverse proportion to the hardness value. The brittle-tough point of the hardness was set around HRC37 after heat treatment in order to balance the strength and the toughness. In addition, the coil wire materials were analyzed from broken section materials showing good toughness; this represented that the area of the cross section radiation layer due to ductile fracture would largely increase. On the contrary, the wire material test fragment with bad toughness represented that the area of the shear layer due to brittle fracture would largely increase as well. As to that material, if its hardness was greater than or equal to HRC37, that material would have an excellent turning danger from transition. At the same time, when the tempering temperature of the wire steel material was set under 4600C and its corresponding central hardness was about HRC37, the distance between two cementite phase layers suddenly increased. This result leaded to the reason why the wire material test fragment was turned into brittleness from ductility. Therefore, when the fastener was manufactured under tempering treatment, avoiding the tempering brittleness temperature range was necessary.

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