Neck Strain Research Articles

Protecting Our Necks

An estimated 4 million rear collisions occur each year in the United States, 1. Insurance Institute for Highway Safety Neck injuries in rear crashes. Status Rep. 2008; 43www.iihs.orgDate accessed: December 8, 2016 Google Scholar with approximately 3 million new whiplash injuries each year. 2. Spine Research Institute of San Diego Whiplash injuries. http://www.srisd.comDate accessed: April 23, 2017 Google Scholar In the United States, auto insurance claims show that neck sprains and strains, commonly known as whiplash, are the most frequently reported injuries, with a cost of about $8 billion annually. 3. Trempel R Zuby D Edwards M IIHS head restraint ratings and insurance injury claim rates. Insurance Institute for Highway Safety, 2015 Google Scholar Thelma C. Kuska, Member, Illinois State Council, is Chair, Injury Prevention Committee, Government Affairs Committee, Palos Heights, IL.

Ranking of osteogenic potential of physical exercises in postmenopausal women based on femoral neck strains.

The current study aimed to assess the potential of different exercises triggering an osteogenic response at the femoral neck in a group of postmenopausal women. The osteogenic potential was determined by ranking the peak hip contact forces (HCFs) and consequent peak tensile and compressive strains at the superior and inferior part of the femoral neck during activities such as (fast) walking, running and resistance training exercises. Results indicate that fast walking (5–6 km/h) running and hopping induced significantly higher strains at the femoral neck than walking at 4 km/h which is considered a baseline exercise for bone preservation. Exercises with a high fracture risk such as hopping, need to be considered carefully especially in a frail elderly population and may therefore not be suitable as a training exercise. Since superior femoral neck frailness is related to elevated hip fracture risk, exercises such as fast walking (above 5 km/h) and running can be highly recommended to stimulate this particular area. Our results suggest that a training program including fast walking (above 5 km/h) and running exercises may increase or preserve the bone mineral density (BMD) at the femoral neck.

Functional morphology in the pages of the AJPA

Functional morphology in the pages of the <i>AJPA</i>

In patients with significant acute muscle strain, is heat or cold more effective for reducing symptoms?

EVIDENCE-BASED ANSWER Either heat and cold therapy applied for 30 minutes combined with ibuprofen provides mild yet similar immediate relief of acute back or neck strains (SOR: C, small RCT). Heat and cold are equivalent in the treatment of acute and chronic low back pain (SOR: B, nonrandomized trial).

Comparing the effect of geometry on the stress-strain response of isolated corrugation structures and corrugation reinforced composite structures

The use of a corrugated geometry can improve necking strain without sacrificing strength when compared to similar structures with a straight geometry. In this work, Finite Element Modeling (FEM) simulations were performed exploring how the presence of a matrix material in a composite impacts the ability of the corrugated structure to improve the necking strain when compared to isolated corrugations with the same geometry. It was found that unlike for isolated corrugations, the degree of corrugation present in a corrugation reinforced composite must exceed a threshold value in order to overcome the improvement in ductility caused by the presence of the matrix. In addition it was shown that it is the unbending of the corrugation that leads to a boost in work hardening which ultimately postpones necking.

Effects of prolonged microscopic work on neck and back strain amongst male ENT clinicians and the benefits of a prototype postural support chair

Musculoskeletal pain is a common occupational hazard experienced by surgeons. Ear, nose and throat (ENT) surgeons are predisposed to neck and back pain due to regular prolonged microscopic work. We conducted a prospective pilot study to investigate the effects of sustained microscopic work on the neck and back, its correlation to surgical experience and to assess the benefits of a prototype postural support chair (PSC) amongst 10 male, ENT clinicians. We used a subjective measure of time to fatigue and pain for the neck and back as well as objective readings from a surface electromyogram (sEMG). We found that an increase in surgical experience correlated with the time taken to experience fatigue and pain in the neck and back. This was corroborated by our sEMG findings. The PSC significantly delayed the sensations in the neck and also eliminated the difference seen amongst the varying seniority of clinicians.

Corrugation Reinforced Composites: A Method for Filling Holes in Material‐Property Space

Material‐property space is filled with holes representing desirable combinations of properties, such as high strength and high necking strain. One way to fill those holes is to use architectured materials. In this work, Finite Element Modeling (FEM) simulations are performed to evaluate composites with a corrugated reinforcement architecture across a range of volume fractions and corrugation heights for a model copper‐steel system. The corrugated reinforcement geometry shows large improvements in necking strain, which increases with corrugation height, without sacrificing strength, and fills a desirable region in material‐property space. Additionally, it is found that the necking strain of a matrix material can be increased by adding a less ductile reinforcing material provided it has a highly corrugated geometry. The improvement in necking strain seen in these composites is attributed to a boost in work hardening that results from an evolving reinforcement alignment as the corrugation unbends.

What governs ductility of ultrafine-grained metals? A microstructure based approach to necking instability

We demonstrate that the conditions for plastic instability, which are traditionally obtained from solid mechanics considerations, also follow from linear stability analysis of the intrinsic evolution laws for the dislocation density. However, the strain rate sensitivity effect enters these conditions in a way different to the known Hart criterion. The necking strain predicted from the dislocation-based models shows good agreement with experimental data, highlighting the primary role played by dynamic dislocation recovery in the stability of uniform plastic flow. In particular, a sharp drop of ductility after plastic deformation to modest strains has been accounted for. A result of special interest with regard to ultrafine-grained materials is the predicted increase of their tensile ductility with increased strain imparted to them by prior severe plastic deformation. Importantly, ductility of such materials was found not to be governed primarily by increased strain rate sensitivity of the flow stress, as is commonly assumed in literature. Rather, it emerges as a result of a decrease in the rate of dynamic recovery of dislocations and the history of the pre-processing by severe plastic deformation.

Prediction of necking in thin sheet metals using an elastic–plastic model coupled with ductile damage and bifurcation criteria

In this paper, the conditions for the occurrence of diffuse and localized necking in thin sheet metals are investigated. The prediction of these necking phenomena is undertaken using an elastic–plastic model coupled with ductile damage, which is then combined with various plastic instability criteria based on bifurcation theory. The bifurcation criteria are first formulated within a general three-dimensional modeling framework, and then specialized to the particular case of plane-stress conditions. Some theoretical relationships or links between the different investigated bifurcation criteria are established, which allows a hierarchical classification in terms of their conservative character in predicting critical necking strains. The resulting numerical tool is implemented into the finite element code ABAQUS/Standard to predict forming limit diagrams, in both situations of a fully three-dimensional formulation and a plane-stress framework. The proposed approach is then applied to the prediction of diffuse and localized necking for a DC06 mild steel material. The predicted forming limit diagrams confirm the above-established theoretical classification, revealing that the general bifurcation criterion provides a lower bound for diffuse necking prediction, while the loss of ellipticity criterion represents an upper bound for localized necking prediction. Some numerical aspects related to the prestrain effect on the development of necking are also investigated, which demonstrates the capability of the present approach in capturing the strain-path changes commonly encountered in complex sheet metal forming operations.

Development of a surrogate model based on patient weight, bone mass and geometry to predict femoral neck strains and fracture loads

Osteoporosis and related bone fractures are an increasing global burden in our ageing society. Areal bone mineral density assessed through dual energy X-ray absorptiometry (DEXA), the clinically accepted and most used method, is not sufficient to assess fracture risk individually. Finite element (FE) modelling has shown improvements in prediction of fracture risk, better than aBMD from DEXA, but is not practical for widespread clinical use. The aim of this study was to develop an adaptive neural network (ANN)-based surrogate model to predict femoral neck strains and fracture loads obtained from a previously developed population-based FE model. The surrogate model performance was assessed in simulating two loading conditions: the stance phase of gait and a fall.The surrogate model successfully predicted strains estimated by FE (r2=0.90–0.98 for level gait load case, r2=0.92–0.96 for the fall load case). Moreover, an ANN model based on three measurements obtainable in clinics (femoral neck length (level gait) or maximum femoral neck diameter (fall), femoral neck bone mass, body weight) was able to give reasonable predictions (r2=0.84–0.94) for all of the strain metrics and the estimated femoral neck fracture load. Overall, the surrogate model has potential for clinical applications as they are based on simple measures of geometry and bone mass which can be derived from DEXA images, accurately predicting FE model outcomes, with advantages over FE models as they are quicker and easier to perform.

Effect of microstructural evolution on deformation behaviour of pre-strained dual-phase steel

The influence of microstructural evolution on the strain hardening and non-uniform deformation behaviour of pre-strained ferrite-martensite DP steel was studied using a crystal plasticity finite element method (CPFEM). The material parameters in the CPFEM were identified through a systematic procedure by fitting models to the experimental results of micro-tensile tests. The CPFEM with the identified parameters were applied to the analysis of virtual models with focus on the microstructural factors such as the angle of interphase boundary, the orientation of habit plane in the martensite phase, and the intensity of texture in the ultrafine-grained ferrite phase developed in the severely-deformed sample. The analysis results suggested the following influences of microstructural factors on the deformation behaviour. The formation of deformation bands in the ferrite phase depends on the configuration of the interphase boundary, the orientation of the habit plane in neighbouring martensite phase and the intensity of texture in the ferrite phase. The suppressions of the deformation bands by controlling microstructure could contribute to later onset of necking and resultant higher strain hardening.

EPIDEMIOLOGY OF INJURIES IN POLE SPORTS: EMERGING CHALLENGES IN A NEW TREND

BackgroundPole sports, such as pole dancing, are recently gaining popularity as a form of fitness, combining dance and acrobatics. Many new, recreational athletes are joining pole sports every year. According...

Femoral Neck Strain during Maximal Contraction of Isolated Hip-Spanning Muscle Groups.

The aim of the study was to investigate femoral neck strain during maximal isometric contraction of the hip-spanning muscles. The musculoskeletal and the femur finite-element models from an elderly white woman were taken from earlier studies. The hip-spanning muscles were grouped by function in six hip-spanning muscle groups. The peak hip and knee moments in the model were matched to corresponding published measurements of the hip and knee moments during maximal isometric exercises about the hip and the knee in elderly participants. The femoral neck strain was calculated using full activation of the agonist muscles at fourteen physiological joint angles. The 5% ± 0.8% of the femoral neck volume exceeded the 90th percentile of the strain distribution across the 84 studied scenarios. Hip extensors, flexors, and abductors generated the highest tension in the proximal neck (2727 με), tension (986 με) and compression (−2818 με) in the anterior and posterior neck, and compression (−2069 με) in the distal neck, respectively. Hip extensors and flexors generated the highest neck strain per unit of joint moment (63–67 με·m·N−1) at extreme hip angles. Therefore, femoral neck strain is heterogeneous and muscle contraction and posture dependent.

Neck Muscle Strain in Air Force Pilots Wearing Night Vision Goggles.

Flight-induced neck pain is common in high performance jet pilots, with incidents frequently attributed to high Gz flight maneuvers. The additional load of helmet-mounted night vision goggles (NVG) is believed to increase the risk, possibly from neck muscle strain in counteracting muscles. Hence, the aim was to investigate the effect of NVG on neck muscle strain as well as on the activity level distribution through a simulated flight session in air force pilots. In this post hoc randomized crossover trial, four senior air force pilots each completed two identical 1.5-h dynamic flight simulations in a human centrifuge: one with a standard helmet and NVG, and one with a standard helmet only. Simulations included repeated exposure to 3-7 Gz, during which neck muscle activity was recorded bilaterally from the anterior neck, the upper and lower posterior neck, and the upper shoulders. The number of muscle activities surpassing 50% of maximum voluntary electrical activity (MVE) and total time of activity at each MVE percentile were compared between NVG and control flights. There was no overall effect in number of neck strain activities between NVG and control flights; however, significantly more activities emerged in the anterior neck. In addition, MVE percentile data showed a tendency of higher activity in the lower posterior neck during NVG flights. The results showed that the additional load of helmet-mounted NVG increases neck muscle strain in anterior stabilizing muscles, indicating that the inertia of head-worn NVG elevates the risk of flight-related neck pain. Pousette MW, Lo Martire R, Linder J, Kristoffersson M, Äng BO. Neck muscle strain in air force pilots wearing night vision goggles. Aerosp Med Hum Perform. 2016; 87(11):928-932.

Effects of intensive microscopic work on neck and back strain and the benefits of a prototype ergonomic chair

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Relation between cervical injuries and helmet use, collision type and speed in motorcycle crashes in Mashhad, Iran

OBJECTIVE: Spinal injuries are among the most important injuries in motorcyclists accounting for 1 to 5% of all injuries in this group with the frequency rising as high as 11% in severe and fatal cases.The most commonly involved areas are thoracic and cervical spines. Injuries to these areas can lead to significant morbidities with life-long complications. In this study, we aim to evaluate the relation of some risk factors including speed of motorcycle at the crash, the type and the mechanism of collision and using helmet with the rate and severity of cervical injury in motorcyclists. PATIENTS AND METHODS: We retrospectively analyzed the medical files of patients with the cervical spinal injury due to motorcycle crash, diagnosed according to ICD10, who were admitted to Shahid Kamyab Trauma Center in Mashhad, Iran from January 2011 to January 2012. Medical files involved in motorcycle crashes were selected and patients who met the inclusion criteria were enrolled to the study. Characteristics of each motorcycle collision for each patient were determined by a traffic specialist from Traffic Police Department. Finally, the medical records were evaluated by a neurosurgery resident to identify the type of the neck injury and determine the Injury Scale Score to assess the severity of the injury. Data was analyzed using SPSS software version 18. RESULTS: A total of 176 patients (mean age: 31.4, 97% male) met the inclusion criteria. Most of the accidents had occurred in rural and suburb roads outside the cities. Of the studied patients, 25 (14.2%) were found to have cervical spine fractures, 27 (15.3%) had neck strain or sprain and 153 (58.5%) had simply neck pain with no sever injuries. Neck fracture was significantly more common among the motorcyclists who had helmet when compared with nonhelmeted.... Language: en

Effect of transport length on in vivo oxidative status and breast meat characteristics in outdoor-reared chicken genotypes

The aim of the study was to evaluate the effect of transport length on in vivo oxidative status and breast meat characteristics in two chicken genotypes reared under free range conditions. A total of 200 male chicks, 100 from fast-growing (Ross 308) and 100 from medium-growing (Naked Neck) strain were used. Fifty-six of these, 28 for genotype, before slaughtering, were randomly allocated to 2 pre-slaughter conditions: absence (0 h) or 4 h of transport. The transport length significantly affected the in vivo oxidative status of broiler greatly reducing the α and δ-tocopherol, retinol and lutein + zeaxanthin content of plasma, and increased the oxidative stress (thiobarbituric acid reactive substances, TBARS) in both strains. Concerning meat quality, the pH (0, 2 and 24 h post-mortem) of breast muscles of chickens transported for 4 h, showed higher values, and respect to strains, Naked Neck had lower values. The pH values were negatively correlated with the lightness (2–24 h) and the shear force of meat. The transport length significantly affected the fatty acid profile of breast muscle, with a decrease in polyunsaturated fatty acids and an increase in TBARS value. Even the antioxidants content of breast was reduced by chicken transport (α-tocotrienol, α-, δ-tocopherol and lutein + zeaxanthin), especially in Naked Neck birds. In conclusion, the results indicate that transport for 4 h prior to slaughter, negatively affect the meat quality of poultry. Slow-growing chickens seem more sensible to stress transport due to the higher kinetic behaviour of these strains.

Effect of Rate Sensitivity on Structural Sandwich Plates with Sinusoidal Corrugated Cores

A plane strain elastic–viscoplastic‐based finite element model is developed to simulate a composite system with sinusoidal corrugated cores under tensile loading conditions. Numerical study shows that the rate sensitivity in the reinforced core provides a positive impact on loading capacity, the necking strain retardation, and improvement in the ductility of a composite. By carefully selecting the reinforced sinusoidal core geometric parameters, extra margin can be gained in improving the uniform elongation without comprising the loading capacity of a composite system. For a given volume fraction of reinforced core, an optimized reinforcement arrangement is found to achieve an improved ductility for a plate with sinusoidal corrugated core.

Experimental study of FLD0 for aluminum alloy using digital image correlation with modified ISO method

AbstractA new material's forming limit diagram (FLD) must be obtained before it can be used for stampings. Compared to conventional methods, the ISO method with a digital image correlation system provides an efficient way to conduct these tests. However the ISO method is position dependent, so the evaluation procedure for aluminum alloy will be seriously affected by the multiple necking strain distribution, resulting in much error. In this paper, a modified ISO method, which can be used for the evaluation of the aluminum alloy FLD, is proposed, and errors resulting from multiple necking were eliminated through detection of the major necking area. An FLD evaluation software was also programmed. An FLD0 punch test was conducted to verify the new modified ISO method. Through comparison of the results with the accepted value, the FLD0 value evaluated from the modified method was determined to be much more accurate than the standard method.

2013 Koiter Medal Paper: Crack-Tip Fields and Toughness of Two-Dimensional Elastoplastic Lattices

The dependence of the fracture toughness of two-dimensional (2D) elastoplastic lattices upon relative density and ductility of cell wall material is obtained for four topologies: the triangular lattice, kagome lattice, diamond lattice, and the hexagonal lattice. Crack-tip fields are explored, including the plastic zone size and crack opening displacement. The cell walls are treated as beams, with a material response given by the Ramberg–Osgood law. There is choice in the criterion for crack advance, and two extremes are considered: (i) the maximum local tensile strain (LTS) anywhere in the lattice attains the failure strain or (ii) the average tensile strain (ATS) across the cell wall attains the failure strain (which can be identified with the necking strain). The dependence of macroscopic fracture toughness upon failure strain, strain hardening exponent, and relative density is obtained for each lattice, and scaling laws are derived. The role of imperfections in degrading the fracture toughness is assessed by random movement of the nodes. The paper provides a strategy for obtaining lattices of high toughness at low density, thereby filling gaps in material property space.