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This study aims to investigate the basic mechanical properties of inflatable antenna reflector material under high-low temperatures.

Uniaxial tensile tests of Kapton (polyimide) foils were conducted in this paper. Kapton foils with a thickness of 25 µm were used and the strip specimens were manufactured according to the machine direction and the transverse direction of the foils.

The stress–strain curves of the foils were obtained under ten temperature conditions (−70°C, −40°C, −10°C, 0°C, 20°C, 50°C, 80°C, 110°C, 140°C, 170°C) after uniaxial tensile tests. Generally speaking, such stress–strain curves are highly nonlinear, and Kapton can be classified into some kind of ductile material without obvious yielding point.

The tests results provide a basis for partial coefficients of Kapton foils strength design value, and meanwhile provide basic material data for the extreme temperature field test in orbit for the inflatable antenna structure in the future.

Based on the curve itself and strain energy theory, for the first time the equivalent yielding point was determined and the mechanism of constitutive curve changing with temperature was explained. Based on curves above, tensile strength, elongation at break, equivalent yielding stress, yielding strain and elastic modulus were analyzed and calculated. By analyzing the mechanical parameters above, the fitting formulas with temperature as the variable were given.

A general first-invariant constitutive model has been derived in literature for incompressible, isotropic hyperelastic materials, known as Marlow model, which reproduces test data exactly without the need of curve-fitting procedures. This paper aims to describe how to extend Marlow’s constitutive model to the more general case of compressible hyperelastic materials.

The isotropic constitutive model is based on a strain energy function, whose isochoric part is solely dependent on the first modified strain invariant. Based on Marlow’s idea, a principle of energetically equivalent deformation states is derived for the compressible case, which is used to determine the underlying strain energy function directly from measured test data. No particular functional of the strain energy function is assumed. It is shown how to calibrate the volumetric and isochoric strain energy functions uniquely with uniaxial or biaxial test data only. The constitutive model is implemented into a finite element program to demonstrate its applicability.

The model is well suited for use in finite element analysis. Only one set of test data is required for calibration without any need for curve-fitting procedures. These test data are reproduced exactly, and the model prediction is reasonable for other deformation modes.

Marlow’s basic concept is extended to the compressible case and applied to both the volumetric and isochoric part of the compressible strain energy function. Moreover, a novel approach is described on how both compressive and tensile test data can be used simultaneously to calibrate the model.

The purpose of this paper is to propose a theoretical model to predict the mechanical behaviour of needle punched heavy geotextiles in uniaxial tensile test.

The model was constructed using theory of layered composite materials and finite element method. The properties of a reference fabric were used as initial data in theoretical calculations and a commercially available finite element program was chosen to carry out stress analysis. A comparison is made between theoretical calculations and experimental data to evaluate the deformation mechanism of geotextile fabrics in uniaxial tensile test.

The results indicate that compatible data were predicted in terms of stress values and stress distribution of fabrics. The inconstant lateral contraction of nonwoven fabrics in tensile test is also successfully simulated by the model. However, in the case of elongations, the model could not predict the strains of heavy geotextiles accurately.

The study aims at predicting the mechanical behaviour of needle punched heavy geotextiles by using the structural and mechanical properties of a “reference fabric” instead of constituent fiber properties.

The relationship between the bulk and localized mechanical properties is critically needed, especially to understand the mechanical performance of solder alloy because of smaller sizing trend of solder joint. The purpose of this paper is to investigate the relationship between tensile and nanoindentation tests toward the mechanical properties and deformation behavior of Sn-3.0Ag-0.5Cu (SAC305) lead-free solder wire at room temperature.

Tensile test with different strain rates of 1.5 × 10-4 s-1, 1.5 × 10-3 s-1, 1.5 × 10-2 s-1 and 1.5 × 10-1 s-1 at room temperature of 25°C were carried out on lead-free Sn-3.0Ag-0.5Cu (SAC305) solder wire. Stress–strain curves and mechanical properties such as yield strength (YS), ultimate tensile strength (UTS) and elongation were determined from the tensile test. Load-depth (P-h) profiles and micromechanical properties, namely, hardness and reduced modulus, were obtained from nanoindentation test. In addition, the deformation mechanisms of SAC305 lead-free solder wire were obtained by measuring the range of creep parameters, namely, stress exponent and strain rate sensitivity, using both of tensile and nanoindentation data.

It was observed that qualitative results obtained from tensile and nanoindentation tests can be used to identify the changes of the microstructure. The occurrence of dynamic recrystallization and the increase of ductility obtained from tensile test can be used to indicate the increment of grain refinement or dislocation density. Similarly, the occurrence of earliest pop-in event and the highest occurrence of pop-in event observed from nanoindentation also can be used to identify the increase of grain refinement and dislocation density. An increment of strain rates increases the YS and ultimate UTS of SAC305 solder wire. Similarly, the variation of hardness of SAC305 solder wire has the similar trend or linear relationship with the variation of YS and UTS, following the Tabor relation. In contrast, the variation of reduced modulus has a different trend compared to that of hardness. The deformation behavior analysis based on the Holomon’s relation for tensile test and constant load method for nanoindentation test showed the same trend but with different deformation mechanisms. The transition of responsible deformation mechanism was obtained from both tensile and nanoindentation tests which from grain boundary sliding (GBS) to grain boundary diffusion and dislocation climb to grain boundary slide, respectively.

For the current analysis, the relationship between tensile and nanoindentation test was analyzed specifically for the SAC305 lead-free solder wire, which is still lacking. The findings provide a valuable data, especially when comparing the trend and mechanism involved in bulk (tensile) and localized (nanoindentation) methods of testing.

This paper aims to investigate the effects of build parameters and strain rate on the mechanical properties of three-dimensional (3D) printed polylactic acid (PLA) by integrating digital image correlation and desirability function analysis. The build parameters included in this paper are the infill density, build orientation and layer height. These findings provide a framework for systematic mechanical characterization of 3D-printed PLA and potential ways of choosing process parameters to maximize performance for a given design.

The Taguchi method was used to shortlist a set of 18 different combinations of build parameters and testing conditions. Accordingly, 18 specimens were 3D printed using those combinations and put through a series of uniaxial tensions tests with digital image correlation. The mechanical properties deduced for all 18 tests were then used in a desirability function analysis where the mechanical properties were optimized to determine the ideal combination of build parameters and strain rate loading conditions.

By comparing the tensile mechanical experimental properties results between Taguchi's recommended parameters and the optimal parameter found from the response table of means, the composite desirability had increased by 2.08%. The tensile mechanical properties of the PLA specimens gradually decrease with an increase in the layer height, while they increase with increasing the infill densities. On the other hand, the mechanical properties have been affected by the build orientation and the strain rate in similar increasing/decreasing trends. Additionally, the obtained optimized results suggest that changing the infill density has a notable impact on the overall result, with a contribution of 48.61%. DIC patterns on the upright samples revealed bimodal strain patterns rendering them more susceptible to failures because of printing imperfections.

These findings provide a framework for systematic mechanical characterization of 3D-printed PLA and potential ways of choosing process parameters to maximize performance for a given design.

Lightweighting of components in the automotive industry is a prevailing trend influenced by both consumer demand and government regulations. As the viability of additively manufactured designs continues to increase, traditionally manufactured components are continually being replaced with 3D-printed parts. The purpose of this paper is to present experimental results and design considerations for 3D-printed acrylonitrile butadiene styrene (ABS) components with non-solid infill sections, addressing a large gap in the literature. Information published in this paper will guide engineers when designing fused deposition modeling (FDM) ABS parts with infill regions.

Uniaxial tensile tests and three-point bend tests were performed on 12 different build configurations of 20 samples. FDM with ABS was used as the manufacturing method for the samples. Failure strength and elastic modulus were normalized on print time and specimen mass to quantify variance between configurations. Optimal infill configurations were selected and used in two automotive case study examples.

Results obtained from the uniaxial tensile tests and three-point bend tests distinctly showed that component strength is highly influenced by the infill choice selected. Normalized results indicate that solid, double dense and triangular infill, all with eight contour layers, are optimal configurations for component regions experiencing high stress, moderate stress and low stress, respectively. Implementation of the optimal infill configurations in automotive examples yielded equivalent failure strength without normalization and significantly improved failure strength on a print time and mass normalized index.

To the best of the authors’ knowledge, this is the first paper to experimentally determine and quantify optimal infill configurations for FDM ABS printed parts. Published data in this paper are also of value to engineers requiring quantitative material properties for common infill configurations.

The purpose of this paper was twofold: first, to determine if rotating bending could be used as an effective way of determining the fatigue behaviour of laser-sintered nylon, and second, to examine whether the fatigue behaviour of laser-sintered PA12 showed any significant anisotropy.

Specimens were measured to obtain dimensional accuracy, density and surface roughness levels. Then, uniaxial tensile and rotating-bending fatigue tests were performed. A purpose-built test-jig has been used to subject hourglass-shaped specimens to reversed bending at two frequencies: 50 and 30 Hz. Additionally, thermal and microstructural analyses were performed to understand the underlying mechanisms of failure.

The experiments suggest PA12 specimens will fail in fatigue following the conventional fatigue mechanisms observed in previous research with ductile polymers. Although high-frequency loading caused a heat build-up in the specimen, temperatures stabilised between 20 and 30°C, suggesting that rotating-bending fatigue at frequencies of up to 50 Hz is a valid way of determining the fatigue behaviour of laser-sintered PA12 specimens. Stresses below 20 MPa led to fatigue lives above 1 million cycles. Some anisotropic behaviour was observed in the fatigue test results, with specimens made orientated with the Z axis showing the lowest fatigue lives on average, but an endurance limit of approximately 15 MPa seems to be common for all specimens regardless of their build orientation.

The observed endurance limit of 15 MPa did not depend significantly on the orientation at which a part was built – meaning that it may be possible to guarantee a service life for a part which does not depend on part orientation within a build. Clearly, good-quality control will also be required to ensure performance, but this has important implications for the design of laser-sintered PA12 parts for realistic service conditions.

To our knowledge, this is the first paper to present rotating-bending fatigue data for laser-sintered PA12 parts, and the first to identify an endurance limit which is independent of part orientation.

Para-aramid fabrics see service in a great variety of applications, such as heavy weight lifting applications, penetration protective multilayer panels, etc. It is, therefore, increasingly important to understand the strain rate range at which the fabric has optimum mechanical properties. Although this is a field that has not been studied before, it is of great significance since it allows for the determination of the fabric’s layer location within the multilayered structure which offers maximum overall performance. The paper aims to discuss this issue.

Rectangular strips of PARAX 300 S8 woven para-aramid fabric underwent uniaxial tensile tests at various extension rates. The angle between two fibers at the center of each specimen was measured after the fabrics were elongated at different tensile extensions. This recovery angle was determined by visual analysis of the test video recordings after specimen unloading. Based on this, the recovery of the weaving form after unloading was also estimated for each tensile extension. A recovery degree based deformation characterization of the sections of a typical load/extension curve has been introduced.

The fabric does not appear to be strain rate sensitive for a strain rate range of 0.03 s-1 to 0.53 s-1, and its load/extension characteristics are generally not affected by the extension rate. However, break load and maximum elongation values appear reduced at actuator velocity of 2,400 mm/min and enhanced at 3,600 mm/min. Finally, the effect of extension rate on the different deformation zones of the material is reported and discussed.

The current research work offers a novel approach for the investigation of non-standard response of woven para-aramid fabrics when subjected to tensile loading under various strain rates. Additionally, a new approach is introduced to explain in detail the deformation zones based on the recovery degree of the fiber orientation angle after unloading.

This paper aims to investigate the structural behaviour of polylactic acid (PLA) parts fabricated by fused deposition modelling (FDM) to support the development of analytical and numerical models to predict the structural performance of FDM components and categories of similar additive manufactured parts.

A new methodology based on uniaxial tensile tests of filaments and FDM specimens, infill measurement and normalization of the results is proposed and implemented. A total of 396 specimens made of PLA were evaluated by using variable process parameters.

The infill and the build orientation have a large influence on the elastic modulus and ultimate tensile stress, whereas the layer thickness and the infill pattern have a low influence on these properties. The elongation at break is not influenced by the process parameters except by the build orientation. Furthermore, the infill values measured on the test specimens differ from the nominal values provided by the system.

The analysis of the structural properties of FDM samples is limited to uniaxial loading conditions.

The obtained results are valuable for the structural analysis and numerical simulation of FDM components and for potential studies using machine learning techniques to predict the structural response of FDM parts.

A new experimental methodology that considers the measurement of the real infill percentage and the normalization of the results for inter-comparison with other studies is proposed. Moreover, a new set of experimental results of FDM-PLA parts is presented and extends the existing results in the literature.

This review paper aims to provide a better understanding of formulation and processing of anisotropic conductive adhesive film (ACF) material and to summarize the significant research and development work for the mechanical properties of ACF material and joints, which helps to the development and application of ACF joints with better reliability in microelectronic packaging systems.

The ACF material was cured at high temperature of 190°C, and the cured ACF was tested by conducting the tensile experiments with uniaxial and cyclic loads. The ACF joint was obtained with process of pre-bonding and final bonding. The impact tests and shear tests of ACF joints were completed with different aging conditions such as high temperature, thermal cycling and hygrothermal aging.

The cured ACF exhibited unique time-, temperature- and loading rate-dependent behaviors and a strong memory of loading history. Prior stress cycling with higher mean stress or stress amplitude restrained the ratcheting strain in subsequent cycling with lower mean stress or stress amplitude. The impact strength and adhesive strength of ACF joints increased with increase of bonding temperature, but they decreased with increase of environment temperature. The adhesive strength and life of ACF joints decreased with hygrothermal aging, whereas increased firstly and then decreased with thermal cycling.

This study is to review the recent investigations on the mechanical properties of ACF material and joints in microelectronic packaging applications.