The damage behavior of carbon fiber reinforced plastics (CFRP) is highly complex due to the overlapping of various damage forms. To elucidate this deformation behavior, it is crucial to evaluate the micro-scale deformation distribution before the occurrence of each type of damage. The sampling Moiré method has been recognized as an effective experimental technique for analyzing such deformation behavior. In this study, we used the sampling Moiré method to calculate the micro-displacement distributions of [±45°]4s CFRP laminates during a three-point bending test under microscopic observation. Additionally, a finite element model was created under the same conditions to compute the displacement distribution using the finite element method (FEM). A comparison of the displacement distributions obtained from both experimental and simulation methods confirmed their consistency. The simulation results also revealed the difference in CFRP displacement distribution characteristics with and without interlayer resin, which manifested that the presence of a resin layer between the CFRP layers induced a distinctive wave displacement distribution when subjected to a three-point bending load.
Defect detection is crucial to the manufacture and evaluation of materials. However, it is still a great challenge to detect the defects in a wide field. In this paper, the two-dimensional (2D) digital multiplication moiré method is presented. The point defects of the crystal are detected visually by employing digital image processing. We mainly discuss the applications of this method to detect the defect and measure the strain in the silicon (Si) single crystals. The strain distributions in the main directions of Si single crystals are measured, and the point defects are detected. Point defects are easier to observe when the atomic structure is amplified using 2D multiplication moiré. The 2D multiplication moiré method that has been used for the point defects detection in Si single crystals described in this paper also lays an important foundation for the detection of strains and defects in the crystal structure of other materials.
The multiplication sampling moiré (MSM) method achieves a strong noise-immunity deformation measurement by performing phase analysis of the second harmonic of grating patterns, which surpasses the limitation of the conventional sampling moiré method that produces phase errors when the first harmonic is submerged by the background noise. In this study, the multiplication sampling moiré method was utilized to investigate the fracture behavior of a [±15°]2s carbon fiber reinforced plastic (CFRP) laminate specimen under different tensile loads. The full-field microscopic strain distribution maps, including the normal, shear, and principal strains, were successfully measured on the cross-section of the CFRP laminates with fiber discontinuities. The results show strain distribution characteristics before and after transverse crack occurrence in the matrix resin region of the CFPR laminates, and the changes in shear strain at the interlayer interfaces before and after the emergence of delamination. The MSM method holds promise for evaluating mechanical properties, fracture behavior, characterizing strain distributions, and residual stresses in deformation measurements of various structural and composite materials.
We proposed a new type of phase transforming auxetic material (PTAM) by embedding magnets into cellular auxetic material with rotating cubes. To find out the effect of magnets on the mechanics of PTAM, several samples were fabricated and attractive magnets were embedded. Quasi-static uniaxial compression tests were performed and the results show that the phase of the material can be successfully changed by embedding attractive magnets,which means this material exhibits from one phase to two phases.
This paper presents a locking device which achieves in locking the rotary feed structure of a space-borne microwave
radiometer during the launch stage. This locking device employs two shape memory alloy (SMA) wires as the actuating
elements, and uses a self-locking structure to achieve the locking function. To improve the performance and reliability, a
redundant SMA wire and a step structure are employed. To validate the proposed SMA locking device, four prototypes
were fabricated and tested. The result shows that the locking device possesses the advantages of remarkable locking
performances, wide operation electric current and high survival temperature. Based on the test results, the locking device
has a great potential for the application of space rotary structures.
The hollow metallic optical fibers not only retain the advantage of flexibility but possess a greater intensity gradient for atomic waveguide. Therefore, based on the vector model of Maxwell’s equations, we exactly calculated the intensity distribution of the TE01 mode in a typical metallic fiber, and analyzed the optical potential for 85Rb atom. Most of all, based on a circular atomic waveguide, we creatively proposed a novel measurement scheme for rotation sensing, explained the specific measurement principle, and built a mathematical model for this novel scheme. By measuring the number of atoms in the final states, we could get the rotation rate for this typical rotation system. This novel rotation sensor not only possessed a higher measurement precision, but realized the continuity measurement. It will be widely used in navigation, geophysics and general relativity.
Spacecrafts require a variety of separation and release devices to accommodate separation from the launch vehicle or
deployment of heat radiation panels, solar arrays and other appendages. In order to overcome drawbacks of the current
release devices, this paper proposes a design scheme of release device with a form of segmented nut and actuated with
SMA (Shape Memory Alloy) wire. In order to validate the release device's function and performance, ground tests
including single device response time tests, synchronous tests of two devices, fatigue life tests were carried out. Tests
results show that the innovative space release device developed in this paper owning the advantages of small size, quick
response, long fatigue life, high simultaneity and auto-reset has a potential use in space engineering.
Development of advanced lightweight solar arrays and small satellites requires deployment and release devices to be
very small and lightweight. Achieving release requirements through a small size device will face more challenging
design problems. The SMA (Shape Memory Alloys) devices designed so far have all been discrete point bolt release
devices. When several release devices are used, it is very hard for present SMA devices to keep synchronous because of
a long individual separation time. This paper will describe the advantages of a new type of space release device actuated
with SMA wire, the design and experimental results to demonstrate its functions. The scheme is to take advantage of the
ability of SMA to recover a parent shape when heated by an electrical current. A clever and simple structure design
ensures small size and light weight of the device. To achieve high release reliability, Tanaka-Liang's constitutive model
was selected to describe SMA wire's deformation and response characteristics. Ground test facilities were designed to
validate numerical prediction. Tests results showed that the small release device actuated with SMA wires can response
very quickly (within 0.1 seconds under satellite power supply of 28V). Synchronous deployment tests were also done
when two release devices were installed at the same time, and also gained success. It is concluded that the developed
SMA release device owning advantages of small size, lightweight, low shock, no contamination, easy reset and
synchronization etc. will play an important role in developing future advanced lightweight solar arrays.
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