Study on inter-ply friction between woven and unidirectional prepregs and its effect on the composite forming process

The application of composites in the aircraft industry has increased significantly over the past few decades. With traditional composite laminate shaping, each layer is made to conform to the mold surface by hand before subsequent layers are added. This is a very labor- and time-intensive process. There is a great deal of interest in developing an automated process for forming composite parts with compound curvatures. The proposed composite forming process utilizes a computer-controlled, reconfigurable discrete element mold to incrementally form a compound curvature part shape from a flat lay-up, thereby facilitating process automation. An elastomeric interpolating layer, called an interpolator, is placed on top of the hemispherical forming ends of the die elements to prevent dimpling of the composite lay-up. The process employs vacuum to pull a single diaphragm (top), composite, and interpolator into contact with the mold surface. Through an experimental investigation, this new composites forming process with “active” tooling has been successfully demonstrated. Heating of the composite is accomplished by uncontained, forced convection using a matrix of heated air jets mounted above the composite. However, low-powered conduction is shown to be the best heating method in terms of both composite heating time and minimization of through-thickness temperature. Using vacuum to conform both the composite and the interpolator to the mold, and choosing sufficiently stiff diaphragm and interpolator materials, undimpled and wrinkle-free composite parts have been formed in an incremental fashion.

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Physico-technical approach to design of composites from mineral and polymer technogenic resources

Environment Technology Resources Proceedings of the International Scientific and Practical Conference ◽

10.17770/etr2015vol1.620 ◽

2015 ◽

Vol 1 ◽

pp. 162 ◽

Cited By ~ 1

Author(s):

Gotfrīds Noviks

Keyword(s):

Composite Materials ◽

Experimental Studies ◽

Process Efficiency ◽

Operating Characteristics ◽

Forming Process ◽

Polymer Waste ◽

Composite Forming ◽

Different Types ◽

Low Levels

Artificial composite materials are currently being produced in large quantities, they are diverse and they are widely used in the economy. There have been extensive theoretical and experimental studies of different types of components, developed the calculation methods of composites production with predefined properties.At the same time industry produces a lot of mineral and polymer waste, which are practically technogenic resources, but their use is currently at quite low levels. The paper examines the possibilities to use technogenic resources- mineral (such as ash and clay) and organic (polymers -PET containers) for producing qualitative composite materials. For this purpose theoretical analysis and calculations of the physical properties of components and process parameters that determine the operating characteristics of the composite material were carried out.Composite-forming process efficiency determinative parameters were analysed: adhesion, the specific surface energy, specific free surface, adsorption capacity and the degree of dispersion of the particles.The role of external factors in processing of composite were examined – temperature, concentration of components.The characteristics of prepared samples of composites showed the possibility to use these waste for the development of qualitative products for different purposes.

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Experimental Study on a Microwave Composite Forming Process Based on a SiC Mold for Manufacturing Fiber Metal Laminate

Materials ◽

10.3390/ma14195547 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5547

Author(s):

Eu-Tteum Park ◽

Jeong Kim ◽

Beom-Soo Kang ◽

Woojin Song

Keyword(s):

Tensile Properties ◽

Thickness Distribution ◽

Microwave Oven ◽

Process Time ◽

Uniaxial Tensile ◽

Manufacturing Cost ◽

Forming Process ◽

Fiber Metal Laminate ◽

Composite Forming ◽

Fiber Metal

The microwave composite forming (MCF) process can reduce manufacturing cost because the process time is reduced by the dielectric heating of the mold and the composite material. In a previous study, the MCF process using a commercial microwave oven with a polytetrafluoroethylene mold was applied. Disadvantages of the previous MCF process have been investigated. These included the difference in tensile properties according to the cutting location, absence of a method to measure temperature during the MCF process, and the fact that the input power cannot be controlled according to the temperature. To solve these problems, a microwave oven with a silicon carbide mold was proposed in this study. Uniaxial tensile tests were conducted to obtain the tensile properties of the fiber metal laminate (FML) specimen. In addition, a microscopic image was captured to investigate the non-adhesive area. The tensile properties and thickness distribution of the FML specimens manufactured by the proposed and previous MCF processes were compared according to the cutting location of the FML sheets. Furthermore, the non-adhesive area was quantified to compare the processes. The results revealed that the proposed MCF process improved the tensile properties of the FML specimen and reduced the non-adhesive area.

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The Potentials of Scanning Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101505 ◽

1968 ◽

Vol 26 ◽

pp. 352-353

Author(s):

A. V. Crewe

Keyword(s):

Salient Feature ◽

Secondary Emission ◽

Resolving Power ◽

X Rays ◽

Scanning Microscope ◽

Forming Process ◽

Additional Tool ◽

Detection Systems ◽

Conventional Microscope ◽

Present Information

If the resolving power of a scanning electron microscope can be improved until it is comparable to that of a conventional microscope, it would serve as a valuable additional tool in many investigations.The salient feature of scanning microscopes is that the image-forming process takes place before the electrons strike the specimen. This means that several different detection systems can be employed in order to present information about the specimen. In our own particular work we have concentrated on the use of energy loss information in the beam which is transmitted through the specimen, but there are also numerous other possibilities (such as secondary emission, generation of X-rays, and cathode luminescence).Another difference between the pictures one would obtain from the scanning microscope and those obtained from a conventional microscope is that the diffraction phenomena are totally different. The only diffraction phenomena which would be seen in the scanning microscope are those which exist in the beam itself, and not those produced by the specimen.

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Microscopy of porous ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154160 ◽

1989 ◽

Vol 47 ◽

pp. 438-439

Author(s):

H. M. Kerch ◽

R. A. Gerhardt

Keyword(s):

Porous Ceramics ◽

Specimen Preparation ◽

High Porosity ◽

Ion Milling ◽

Forming Process ◽

Preparation Methods ◽

Pore Texture ◽

Proper Design ◽

And Function ◽

Function Information

Highly porous ceramics are employed in a variety of engineering applications due to their unique mechanical, optical, and electrical characteristics. In order to achieve proper design and function, information about the pore structure must be obtained. Parameters of importance include pore size, pore volume, and size distribution, as well as pore texture and geometry. A quantitative determination of these features for high porosity materials by a microscopic technique is usually not done because artifacts introduced by either the sample preparation method or the image forming process of the microscope make interpretation difficult.Scanning electron microscopy for both fractured and polished surfaces has been utilized extensively for examining pore structures. However, there is uncertainty in distinguishing between topography and pores for the fractured specimen and sample pullout obscures the true morphology for samples that are polished. In addition, very small pores (nm range) cannot be resolved in the S.E.M. On the other hand, T.E.M. has better resolution but the specimen preparation methods involved such as powder dispersion, ion milling, and chemical etching may incur problems ranging from preferential widening of pores to partial or complete destruction of the pore network.

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Platelet Microtubules in Clot Structure Formation and Contractile Force Generation: Investigation of a Controversy

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661596 ◽

1986 ◽

Vol 56 (01) ◽

pp. 023-027 ◽

Cited By ~ 9

Author(s):

C J Jen ◽

L V McIntire

Keyword(s):

Network Formation ◽

Contractile Force ◽

Second Phase ◽

Clot Retraction ◽

Forming Process ◽

Microtubule Organization ◽

Physiological Processes ◽

Fibrin Network ◽

Two Parameters

SummaryWhether platelet microtubules are involved in clot retraction/ contraction has been controversial. To address this question we have simultaneously measured two clotting parameters, clot structural rigidity and isometric contractile force, using a rheological technique. For recalcified PRP clots these two parameters began rising together at about 15 min after CaCl2 addition. In the concentration range affecting microtubule organization in platelets, colchicine, vinca alkaloids and taxol demonstrated insignificant effects on both clotting parameters of a recalcified PRP clot. For PRP clots induced by adding small amounts of exogenous thrombin, the kinetic curves of clot rigidity were biphasic and without a lag time. The first phase corresponded to a platelet-independent network forming process, while the second phase corresponded to a platelet-dependent process. These PRP clots began generating contractile force at the onset of the second phase. For both rigidity and force parameters, only the second phase of clotting kinetics was retarded by microtubule affecting reagents. When PRP samples were clotted by adding a mixture of CaCl2 and thrombin, the second phase clotting was accelerated and became superimposed on the first phase. The inhibitory effects of micro tubule affecting reagents became less pronounced. Thrombin clotting of a two-component system (washed platelets/ purified fibrinogen) was also biphasic, with the second phase being microtubule-dependent. In conclusion, platelet microtubules are important in PRP clotted with low concentrations of thrombin, during which fibrin network formation precedes platelet-fibrin interactions. On the other hand they are unimportant if a PRP clot is induced by recalcification, during which the fibrin network is constructed in the presence of platelet-fibrin interactions. The latter is likely to be more analogous to physiological processes in vivo.

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Study of the process of forming a hole for a thread at manufacturing a high nut

Ferrous Metallurgy Bulletin of Scientific Technical and Economic Information ◽

10.32339/0135-5910-2020-8-841-846 ◽

2020 ◽

Vol 76 (8) ◽

pp. 841-846

Author(s):

I. G. Shubin ◽

A. A. Kurkin

Keyword(s):

Metal Flow ◽

Nonlinear Dependence ◽

Geometrical Parameters ◽

Relative Height ◽

Forming Process ◽

Normal Height ◽

Accuracy Class ◽

Limit Values ◽

Program Complex ◽

Class B

During manufacturing nuts of increased height, a problem of obtaining correct cylindrical form of the hole for thread and overall geometrical parameters arises. To solve the problem it is necessary to know regularity of the blank forming process. Results of the study of a technological process of high hexahedral nuts forming presented. The nuts were M18 of 22 mm height, M16 of 19 mm height and M12 of normal height 10 mm according to GOST 5915–70, accuracy class B, steel grade 10 according to GOST 10702–78. The volumetric stamping was accomplished at the five-position automatic presses of АА1822 type. It was determined, that unevenness of the metal flow in the process of plastic deformation of blanks of increased height nuts was caused by different stress conditions by their sections. To simulate the mode of deformation, the program complex QForm-3D was chosen. The complex ensured to forecast with necessary accuracy the metal flow in a blank, as well as to define the deformation force and arising stress in the working instrument. The simulation showed the presence of regularity between preliminary formed buffle and deviation of dimensions and form of a blank wall after its finishing piercing, which can be expressed by a nonlinear dependence. The limit values of the relative height of the buffle С/D = 0.56–0.588 defined, exceeding which will result in rejection of the finished product. Accounting the limit values of the relative height of the buffle will enable to correct a mode of technological operations and technological instruments at stamping of high hexahedral nuts.

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Upscaling of foam forming technology for pilot scale

TAPPI Journal ◽

10.32964/tj18.8.461 ◽

2019 ◽

Vol 18 (8) ◽

Cited By ~ 1

Author(s):

JANI LEHMONEN ◽

TIMO RANTANEN ◽

KARITA KINNUNEN-RAUDASKOSKI

Keyword(s):

Production Efficiency ◽

Strength Loss ◽

Pilot Scale ◽

Foam Density ◽

Forming Process ◽

Production Scale ◽

Forming Technology ◽

Wet Pressing ◽

Foam Forming ◽

Board Industry

The need for production cost savings and changes in the global paper and board industry during recent years have been constants. Changes in the global paper and board industry during past years have increased the need for more cost-efficient processes and production technologies. It is known that in paper and board production, foam typically leads to problems in the process rather than improvements in production efficiency. Foam forming technology, where foam is used as a carrier phase and a flowing medium, exploits the properties of dispersive foam. In this study, the possibility of applying foam forming technology to paper applications was investigated using a pilot scale paper forming environment modified for foam forming from conventional water forming. According to the results, the shape of jet-to-wire ratios was the same in both forming methods, but in the case of foam forming, the achieved scale of jet-to-wire ratio and MD/CD-ratio were wider and not behaving sensitively to shear changes in the forming section as a water forming process would. This kind of behavior would be beneficial when upscaling foam technology to the production scale. The dryness results after the forming section indicated the improvement in dewatering, especially when foam density was at the lowest level (i.e., air content was at the highest level). In addition, the dryness results after the pressing section indicated a faster increase in the dryness level as a function of foam density, with all density levels compared to the corresponding water formed sheets. According to the study, the bonding level of water- and foam-laid structures were at the same level when the highest wet pressing value was applied. The results of the study show that the strength loss often associated with foam forming can be compensated for successfully through wet pressing.

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