Multiscale tool-fabric contact observation and analysis for composite fabric forming

This paper provides measurements and analysis at the meso and microscopic scales of the real contact area between twill carbon fabric and a flat glass counterface. The mesoscopic contact area associated with tow contacts is about 55–75% of the nominal area. However, the total real contact length within the tow contacts, associated with microscopic contact at the fibre level, is only 4–8% of the idealised contact conditions with parallel touching fibres, for a nominal contact pressure of around 2 kPa. The dependence of real contact area on fabric shear angle is also investigated. The estimated real contact pressure is 15,000 times higher than the nominal contact pressure. Models or experiments of friction in composites forming which do not take into account the real contact situation, which is very far from an idealised packing arrangement, may fail to capture the essential tribological mechanisms.The authors are very grateful to the Tribology groups of the LTDS laboratory in Lyon and Imperial College, London for help with the semi-reflective coatings. We also acknowledge the contribution of our industrial partners Jaguar Land Rover and Granta Design Ltd, as well as the academic partners from the Composites group at the University of Nottingham. This work was funded by an Engineering and Physical Sciences Research Council grant (reference EP/K032798/1).This is the final published version. It first appeared at http://www.sciencedirect.com/science/article/pii/S1359835X15000986#

Novel Experimental Method for Microscale Contact Analysis in Composite Fabric Forming

This paper describes a novel experimental rig and associated experimental method developed to investigate composite fabric/tool contact at the microscopic scale. A key feature of this method is that it enables direct observation of real contact at the scale of fibres and the evolution of this contact under simultaneous application of shear and compression loads. To observe the contact, an optical semi-reflective coating is used. An algorithm is developed to analyse the contact images and measure the real contact length and orientation of individual fibres. The method is applied to microcontacts of carbon twill fabric. The real contact length under an apparent pressure of 1.9 kPa is surprisingly small compared to the apparent contact length. Transverse forces associated with friction are also measured. However these results are difficult to interpret as the test generates friction forces which differ from those which would be seen in conventional sliding friction tests.The authors are very grateful to Nazario Morgado and Dr Juliette Cayer-Barrioz from the LTDS laboratory in Lyon (France) for the calculations of the optical properties of semi reflective coatings, and to the Tribology Group of Imperial College London for help with these coatings. We also acknowledge the contribution of our industrial partners Jaguar Land Rover and Granta Design Ltd, as well as the academic partners from the Composites group at the University of Nottingham. This work was funded by an Engineering and Physical Sciences Research Council grant (reference EP/K032798/1).This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s11340-015-0044-y. Related research data is available at: https://www.repository.cam.ac.uk/handle/1810/24724

Friction of carbon fibre tows

The fundamental frictional behaviour of carbon fibre tows relevant to composite fabric forming is explored. Tow-on-tool and tow-on-tow contact are considered. For tow-on-tool contact, an experiment is devised to simultaneously observe the true filament contact length and measure the friction force over a range of normal loads. Filament contact length is not constant, as would be given from an idealised assumption of parallel touching filaments, but increases in a characteristic manner with normal load. Friction force follows a power law variation with normal load with exponent in the range 0.7–1. Accounting for the evolving contact length in a Hertzian calculation of the real contact area produces a contact area versus load variation which differs only by a constant factor from the measured friction force curves. Thus, the results agree with a ‘constant interface strength’ model of friction. Tow orientation and sizing are found to have a significant effect on friction by altering the real contact area.Engineering and Physical Sciences Research Council (Grant ID: EP/K032798/1 (Friction in Composites Forming)), Jaguar Land Rover, Granta Design Ltd, Composites Research Group at the University of Nottingham, Hexcel U

A Novel Method of Extraction of Blend Component Structure from SANS Measurements of Homopolymer Bimodal Blends

A new method is presented for the extraction of single-chain form factors and interchain interference functions from a range of small-angle neutron scattering (SANS) experiments on bimodal homopolymer blends. The method requires a minimum of three blends, made up of hydrogenated and deuterated components with matched degree of polymerization at two different chain lengths, but with carefully varying deuteration levels. The method is validated through an experimental study on polystyrene homopolymer bimodal blends with inline image. By fitting Debye functions to the structure factors, it is shown that there is good agreement between the molar mass of the components obtained from SANS and from chromatography. The extraction method also enables, for the first time, interchain scattering functions to be produced for scattering between chains of different lengths

Assessment of serological tests for antibodies to different antigens of the SARS-CoV-2 virus: comparison of six immunoassays

The new coronavirus SARS-CoV-2 has become a global challenge to medicine and, in particular, laboratory diagnostics. The study of the antibodies’ level to SARS-CoV-2 can be used as a confirmation test in the diagnosis of a disease, but it becomes of paramount importance in assessing population immunity resulting from a disease or vaccination, as well as in selection of convalescent plasma donors. The kits developed in our country and abroad for detecting antibodies to the SARS-CoV-2 virus differ both in the methods of testing and in the used coronavirus antigens to which the antibodies are directed. The aim of this study was to compare the diagnostic sensitivity and specificity of five kits for the detection of IgG antibodies to the SARS-CoV-2 virus, based on different diagnostic methods. Serum samples from 137 COVID-19 convalescents and 166 donors of blood and its components were examined. The control group consisted of 50 blood sera collected at the beginning of 2019 and 19 sera collected in 2018 (before the advent of the SARS-CoV-2 virus) and stored at -70 °C. Testing was carried out in analytical systems: rapid test “COVID-19 IgM/IgG Rapid Test (Colloidal Gold)” (China), on an automatic immunochemical analyzer Abbott Architect™ i2000 and kit “SARS-CoV2-IgG” (Abbot, Chicago , IL USA), by the chemiluminescence method using an automatic analyzer of the CL series and kits of the “Mindray” company (China) “SARS-CoV-2 IgM” and “SARS-CoV-2 IgG” and by the enzyme immunoassay method on the kits of the companies “Diagnostic Systems” Ltd (Russia, Nizhny Novgorod) “DS-IFA-ANTI-SARS-CoV-2-G”, “Xema” Ltd (Federal State Budgetary Institution “National Medical Research Center of Hematology” of the Ministry of Health of Russia) “SARS-CoV-2-IgG-IFA” and “Vector-Best” CJSC (Russia, Novosibirsk)” SARS-COV-2-IgM-IFA-BEST” and “SARS-COV-2-IgG-IFABEST”. When comparing the results of testing 137 plasma samples on the Vector-Best and Mindray kits for IgG antibodies, 127 samples were positive, 7 samples were negative on both kits, the discrepancy was 2.2%. In the study of IgM antibodies, 32.1% were positive, and 52.6% were negative in both kits. The discrepancy rate was 15.3%. Out of 166 samples, 1 serum (0.6%) was negative in 5 kits. On the Mindray kit, IgG antibodies to the antigens of the SARS-CoV-2 virus were detected in 165 samples (99.4%), on Vector-Best – in 164 sera (98.8%), on Diagnostic systems – in 151 (90.96%), on Xema – in 154 (92.8%), and on Abbott – in 155 samples (93.4%). At the same time, 135 (81.33%) samples were positive in all kits, while 30 samples had discordant results (18.07%), and in 9 sera, specific IgG was not detected in 2 or more kits. ROC analysis revealed a high diagnostic value of all tested kits (AUC from 0.908 to 0.998), which indicates a high quality of the separation model of positive and negative samples (p < 0.001). With the cut-off set by the manufacturers, the sensitivity and specificity ranged from 82.8% and 93.3% for the Diagnostic Systems kit to 99.4% and 95.8% for the VectorBest kit. The calculated correlation coefficients were higher between kits with a similar composition of the antigen used in the kits; therefore, it is better to monitor the dynamics of antibodies by diagnostic kits from the same manufacturer

ЗАКОНОМЕРНОСТИ ФОРМИРОВАНИЯ ДВИГАТЕЛЬНОГО СТЕРЕОТИПА УПРАВЛЕНИЯ ТЕЛОМ В ФАЗЕ ПОЛЕТА У СПОРТСМЕНОВ

Materials and methods. Regularities of movement patterns in the body control the flight phase of the athletes on the example of the long jump were studied by methods of Motion Tracking and electromyography. The findings suggest that a significant difference of motor stereotypes underlying the performance of motor actions – the long jump – in different skill athletes.Results. In the initial phase (phase jumping) differences between the groups are small - repulsion athletes perform in a similar manner, a core group of athletes with a more efficient use of the reserve of the work of the knee. The nature of the work the leg muscles in athletes of both groups in this phase is also not different. However, the further execution of motor actions in athletes of both groups occurs in different ways. Athletes of the control group did not perform virtually control the body in flight phase. This is evidenced primarily high tone muscles in the arms, back and neck throughout the flight phase. Movements are performed only in the knee and hip joints, and already in the phase of “hang-up” – the highest point of the flight path - these movements have focused on the preparation for landing.Conclusions. Athletes of the main group in the flight phase involve the full range of movements - flexion and extension are performed as in the shoulder and elbow joints, as well as in the neck and spine joints. All these movements are designed to increase the range of jumps - this contributes to the removal of the legs forward, and giving the body angular acceleration by the movement of legs and head. Preparation for landing is made directly before contact with the surface, but the very nature of the phase of flight allows the athlete to use the inertia of motion of the body as much as possible to lengthen the jump and thus facilitate shock absorption and retention of balance upon landing.Formation movement patterns in the body control the flight phase of the athletes in the performance of the long jump is caused first of all a transformation of the dominant, defining the objective of motor actions - from a safe landing at the beginning to a maximum distance of the jump from qualified athletes. The result is a motor stereotype that includes only foot traffic at beginners, is complemented by the involvement of the movements of hands and body, reducing the degree of fixation of joints in high-skilled athletes. Цель исследования: изучить закономерности формирования двигательного стереотипа управления телом в фазе полета у спортсменов на примере выполнения прыжка в длину.Материал и методы. Было обследовано 30 мужчин в возрасте 17–24 лет. По степени сформированности двигательного навыка они были разделены на две группы. В основную группу вошли легкоатлеты высокой квалификации – мастера спорта и кандидаты в мастера спорта (16 человек). Контрольную группу составили студенты (14 человек), не имеющие спортивных разрядов. Использовались методы отслеживания движения Motion Tracking и электромиографии.Результаты. В начальную фазу (фаза выпрыгивания) различия между группами незначительны. Отталкивание спортсмены выполняли сходным образом, спортсмены основной группы при этом более эффективно использовали резерв работы коленных суставов. Характер работы мышц ног у спортсменов обоих групп в этой фазе также не различался. Однако дальнейшее выполнение двигательного действия у спортсменов основной и контрольной групп происходило по-разному.Спортсмены контрольной группы практически не осуществляли управления телом в фазе полета. Об этом свидетельствует прежде высокий тонус мышц рук, спины и шеи на протяжении всей фазы полета. Движения выполнялись только в коленном и тазобедренном суставах, причем уже в фазе «зависания» – высшей точке траектории полета – эти движения направлены на подготовку к приземлению. Спортсмены основной группы в фазе полета задействовали весь спектр возможных движений. Сгибания и разгибания выполнялись в плечевых и локтевых суставах, а также в суставах шеи и позвоночника. Все эти движения направлены на увеличение дальности прыжка, этому способствует и вынос ног вперед, и придание телу углового ускорения за счет движения голеней и головы. Подготовка к приземлению производилась непосредственно перед контактом с поверхностью, однако сам характер фазы полета позволял спортсмену максимально использовать инерцию движения тела для удлинения прыжка, тем самым облегчая амортизацию удара, и удержания равновесия после приземления.Формирование двигательного стереотипа управления телом в фазе полета у спортсменов при выполнении прыжка в длину обусловливается прежде всего трансформацией доминанты, определяющей цель двигательного действия – с безопасного приземления у начинающих на максимальную дальность прыжка у квалифицированных спортсменов. В результате формирующийся двигательный стереотип, включающий только движения ног у начинающих спортсменов, дополняется вовлечением движений рук и корпуса, снижением степени фиксации в суставах у спортсменов высокой квалификации.Заключение. Полученные данные свидетельствуют о существенном различии двигательных стереотипов, лежащих в основе выполнения двигательного действия – прыжка в длину – у спортсменов различной квалификации.

Novel Experimental Method for Microscale Contact Analysis in Composite Fabric Forming

This paper describes a novel experimental rig and associated experimental method developed to investigate composite fabric/tool contact at the microscopic scale. A key feature of this method is that it enables direct observation of real contact at the scale of fibres and the evolution of this contact under simultaneous application of shear and compression loads. To observe the contact, an optical semi-reflective coating is used. An algorithm is developed to analyse the contact images and measure the real contact length and orientation of individual fibres. The method is applied to microcontacts of carbon twill fabric. The real contact length under an apparent pressure of 1.9 kPa is surprisingly small compared to the apparent contact length. Transverse forces associated with friction are also measured. However these results are difficult to interpret as the test generates friction forces which differ from those which would be seen in conventional sliding friction tests.The authors are very grateful to Nazario Morgado and Dr Juliette Cayer-Barrioz from the LTDS laboratory in Lyon (France) for the calculations of the optical properties of semi reflective coatings, and to the Tribology Group of Imperial College London for help with these coatings. We also acknowledge the contribution of our industrial partners Jaguar Land Rover and Granta Design Ltd, as well as the academic partners from the Composites group at the University of Nottingham. This work was funded by an Engineering and Physical Sciences Research Council grant (reference EP/K032798/1).This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s11340-015-0044-y. Related research data is available at: https://www.repository.cam.ac.uk/handle/1810/24724

Raw and Analysed through the Cyclic Indentation Method Data for HDPE, PMMA and PR520 epoxy polymers

This is the data to accompany the research article "Cyclic indentation method for polymers: instantaneous elastic modulus from reloading and energy analysis." by Dr Olga Smerdova, Dr Marina Pecora and Prof Marco Gigliotti to be published in Polymer Testing

Raw and Analysed through the Cyclic Indentation Method Data for HDPE, PMMA and PR520 epoxy polymers

This is the data to accompany the research article "Cyclic indentation method for polymers: instantaneous elastic modulus from reloading and energy analysis." by Dr Olga Smerdova, Dr Marina Pecora and Prof Marco Gigliotti to be published in Polymer Testing.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Novel Experimental Method for Microscale Contact Analysis in Composite Fabric Forming

This paper describes a novel experimental rig and associated experimental method developed to investigate composite fabric/tool contact at the microscopic scale. A key feature of this method is that it enables direct observation of real contact at the scale of fibres and the evolution of this contact under simultaneous application of shear and compression loads. To observe the contact, an optical semi-reflective coating is used. An algorithm is developed to analyse the contact images and measure the real contact length and orientation of individual fibres. The method is applied to microcontacts of carbon twill fabric. The real contact length under an apparent pressure of 1.9 kPa is surprisingly small compared to the apparent contact length. Transverse forces associated with friction are also measured. However these results are difficult to interpret as the test generates friction forces which differ from those which would be seen in conventional sliding friction tests