Long-period Structures Research Articles

Vulnerability of structures designed with seismic provision due to explosions in mines

The effect of blast-induced ground vibration on structures was examined. The aim was to investigate the extent to which the strength attributed by seismic design can resist the effect of mine blasts, as both earthquakes and blasts generate lateral forces. The study was conducted to see whether and how blasts can be controlled such that seismic design of structures may suffice the purpose of withstanding mine blasts. The responses in the elastic and post-elastic regions were compared for implementation of the concept of performance-based design. The responses of structures were investigated for both single and sequential blasts. The results showed that sequential blast events are more damaging than earthquakes. On the other hand, medium- and long-period structures under a single blast event can withstand blast-induced vibration if designed as per seismic provisions. To safeguard structures under sequential blasts, it is recommended that the number of blast events is controlled. The safety of structures under blast can be determined by knowing the additional strength attributed from the seismic effect. This may help to decide whether separate design provisions for blast-induced ground motion are needed.

Exact Solution of Nonlinear TVMD Based on Maximizing Damping Enhancement Effect for Acceleration Response Control

The tuned viscous mass damper (TVMD) exhibits superior control effect and energy dissipation capability compared to the viscous damper (VD). Existing literature has primarily focused on the control of absolute acceleration response in structures by linear TVMD, with limited research on nonlinear damper for controlling structural performance and efficiency. This study proposes a methodology for determining the optimal parameters of linear TVMD. The closed-form solution of the nonlinear TVMD is derived through stochastic linearization based on the linear TVMD, aiming to minimize the damping ratio of TVMD by utilizing the damping enhancement effect of the system. For lightly damped structures, the closed-form solution remains a reliable method for accurately approximating TVMD design parameters. Compared to traditional fixed-point theory, the TVMD developed through the proposed methodology demonstrates superior control performance, especially in terms of absolute acceleration, with a smaller damping ratio and minimal deviation from the optimal state of the TVMD. Additionally, the study investigated the influence of the damping index on the optimal parameters and the efficacy of the TVMD in vibration control. It is observed that reducing the damping index can improve structural performance, particularly in long-period structures with small mass ratios, although it may reduce the efficiency of the TVMD. Notably, TVMDs with lower mass ratios maintain higher efficiency regardless of the structural natural period. The damping index does not affect the optimal frequency ratio or the mean square response. Ultimately, the effectiveness of the optimization method is displayed through the examination of response spectra following 22 real seismic events, showcasing its adaptability across various structural types. The comparison of the root-mean-square response between the VD and TVMD across different periods shows consistent results, with a maximum deviation of only 10%. The TVMD is highly effective at regulating the structural response, excelling particularly in controlling the absolute acceleration of long-period structures, where it reduces maximum absolute acceleration by 20% more than displacement. The proposed exact solution rapidly and precisely identifies the design parameters of nonlinear TVMD by the desired specifications, thereby offering theoretical guidance for practical engineering applications.

Twinning and 9R Phase Transition Mediated Extraordinary Cold-drawn Deformability in NiCoCrFeMo High-Entropy Alloy.

The production and application of materials are evolving towards the low-dimensional micro-nano scale. Nevertheless, the fabrication of micron-scale alloy fibers remains a challenge. Herein, a novel Ni-Co-Cr-Fe-Mo high-entropy alloy (HEA) fiber with a cold-drawn reduction rate of 99.9995% and a strain (ɛ) of 12.19 is presented without requiring intermediate annealing. The exceptional deformation strain of 11.62 within the fiber leads to extraordinary tensile strengths of 2.8GPa at room temperature and 3.6GPa at 123K. The in-depth investigation of the microstructure of fibers has revealed the cold drawing deformation mechanisms mediated by the synergistic effects of plane defects. Specifically, various geometrically necessary dislocation interfaces, such as dislocation walls and microbands, along with deformation twins and long-period 9R structures, form in response to external stress when ɛ≤2.7. As the strain increases, the saturated layered structure emerges and progressively evolves into a 3D equiaxed crystal. Moreover, the formation and evolution of the 9R structure (i.e., the migration of incoherent twin boundaries), coupled with the interaction of partial dislocations and the role of deformation twins, are crucial factors determining the fiber's plastic response. This work provides a novel approach to discovering new high-strength metallic fibers with excellent deformability through plane defects engineering.

Structures of the First Epitaxial Layer Created in Colloidal Heteroepitaxy.

Brownian dynamics simulations have been performed to investigate the structural dependence of the first epitaxial layer in colloidal heteroepitaxy. When the epitaxial particles were larger than the substrate particles and the interactions were dominated by the depletion force, a hexagonal structure formed on a closely packed hexagonal substrate. The orientation of this hexagonal structure varied with the size ratio of the epitaxial to substrate particles to make the interaction between the substrate and epitaxial particles strong. When the sizes of the substrate and epitaxial particles were similar, long-period structures formed instead of hexagonal structures to strengthen the interaction between the substrate and epitaxial layer at the expense of the interaction between particles in the first epitaxial layer.

Heterogeneous microstructure of γ-irradiated pre-oxidized PAN fiber revealed by microfocus SR-SAXS reconstruction and molecular simulation.

The microstructure plays a crucial role in the manufacturing and application of polyacrylonitrile fibers, which serve as precursors for carbon fibers. Synchrotron radiation small angle x-ray scattering (SR-SAXS) is a non-destructive and precise technique for analyzing fiber structures. This study employed one-dimensional SR-SAXS mapping to extract key structural parameters such as periodicity, lamellae thickness, and the extent of amorphous regions, as well as the directional orientation in γ-irradiated, pre-oxidized polyacrylonitrile fibers. The analysis revealed a three-layered structure comprising a surface skin, a transitional layer, and a central core. Notably, the lamellar thickness exhibits a "U"-shaped distribution, while the long-period structures, amorphous regions, and orientational properties demonstrate a "wave-like" pattern. Within this structure, the skin exhibits a higher level of orientation, with the orientation decreasing progressively from the skin toward the core layer. The structure of the layered crystal was further corroborated by the morphological analysis. In addition, molecular simulations were performed to propose the mechanisms underlying the formation of this layered structure. This comprehensive investigation using SR-SAXS and one-dimensional mapping provides detailed insights into the microstructural and morphological characteristics of polyacrylonitrile fibers, which can inform future advancements in material processing and refinement techniques for the production of advanced fibers.

Simplified assessment of structures with clutching inertia-friction systems by equivalent linearization methods

The innovative Clutching Inertia System (CIS), has garnered increasing recognition for its effectiveness in mitigating structural vibrations. To enhance the efficiency of passive CIS, introducing suitable energy dissipation mechanisms for the rotational inertia component is imperative. This study delves into the dynamic behavior of CIS, augmented with additional friction damping. Initially, the influence of supplementary friction damping within the CIS framework is examined through a dynamic model of a Single-Degree-of-Freedom (SDOF) system, integrated with the CIS and incorporating the Coulomb friction model. Subsequently, to streamline the dynamic analysis of the CIS and optimize the friction force thereby enhancing control efficiency while minimizing inactive durations, the paper introduces two distinct Equivalent Linearization Methods (ELMs). Furthermore, an assessment of the CIS’s dynamic performance, subjected to various external excitations, is presented. The findings highlight the crucial role of supplemental friction damping in reducing the inactivity of CIS and enhancing its overall control effectiveness. The employed ELMs demonstrate commendable accuracy and practicality for both response assessment and CIS performance optimization. In essence, the CIS, when integrated with supplemental friction damping, exhibits superior performance in suppressing structural displacement responses across diverse excitations, particularly in longer-period structures. Conversely, a more pronounced efficacy in mitigating structural acceleration responses is observed in structures with shorter periods. The study concludes that enhancing the CIS’s supplemental friction damping is more advantageous than increasing the inertia for structural displacement response control.

Simultaneous Measurement of Two-Trace Two-Dimensional (2T2D) Near-Infrared (NIR) Asynchronous Correlation Spectra and Small-Angle X-ray Scattering (SAXS) to Characterize Thermally Aged Polypropylene (PP).

In this study, a new system was developed to carry out simultaneous near-infrared (NIR) and small-angle X-ray scattering (SAXS) measurements. Aged polypropylene (PP) was examined with the NIR-SAXS system to demonstrate how it can be utilized to derive pertinent information about the polymer structure. Pairs of SAXS profiles and NIR spectra of PP in its initial state and after aging were measured to derive an in-depth understanding of the aging phenomenon. The SAXS profiles of the PP samples showed a clear shift of the SAXS peak to the lower q direction induced by the thermal aging, indicating an increase in the length of the long-period structure. Two-trace two-dimensional (2T2D) asynchronous correlation spectra derived from NIR spectra clearly revealed that the aging treatment leads to a substantial increase in the spectral intensity of the regularity bands representing the longer helix present in a folded lamellar structure. In other words, it suggests that the long helix structure is more abundantly present than the short helix structure in the aged PP than in the initial PP. By combining the information derived from the SAXS profiles and NIR spectra, the details of the aging-induced variation were clearly determined. Namely, aging causes additional crystallization of the PP by developing more helical structures, which involves an increase in the lamellar thickness as well as a decrease in the amorphous region. The growth of the rigid crystalline phase restricts the elastic deformation in the amorphous structure, which eventually induces the deterioration of PP by making the polymer hard but brittle. Such observation, in turn, implies that retarding or accelerating the crystallized structure of PP substantially works to control the progress of aging.

Enhanced mechanical properties of LPSOp/Mg composites using super high pressure treatment

The super high pressure (SHP) technique was employed to fabricate the magnesium matrix composites (MMCs) reinforced with long-period stacking order structure powder (LPSOp) by cubic-anvil large-volume press with six rams. The LPSOp was optimized through high energy ball milling (HEBM) with a chemical composition of Mg85Zn6Y9 (at%). The microstructure and mechanical properties of LPSOp/Mg composite was characterized by X-ray diffraction (XRD), scanning electron microscopy/transmission electron microscopy (SEM/EDS), transmission electron microscopy (TEM), microhardness and compressive tests. The microhardness of LPSOp exhibits a notable increase after HEBM, and the thermal stability of LPSOp is affirmed through elevated annealing. The SHPed LPSOp/Mg consists of Mg and LPSO phase. Upon annealing at 400 °C for 1 h, the LPSO phase precipitates from solid solution of Mg and W phase is also identified. The strength of composites by SHP treatment and subsequently annealing is significantly improved compared with the pure Mg without LPSOp, which demonstrates the maximum compression yield strength (CYS) of 250 MPa and ultimate compression strength (UCS) of 375 MPa with satisfactory ductility. The enhanced mechanical properties are attributed to the synergistic reinforcement effects of the dispersed and 3D skeletal structure of LPSOp with excellent interfacial bonding, the coexistence of nano-scale LPSO and W phase and partial solid solution strengthening.

Hierarchically heterogeneous microstructure and mechanical properties in laser-directed energy deposition of γ-TiAl alloy through intrinsic cyclic heat treatment

The complex thermal effects of laser direct energy deposition (L-DED) provide significant advantages for production of high-performance γ-TiAl alloy, whereas challenges still exist in microstructure tailoring and mechanical properties. This work focuses on the influence of intrinsic cyclic heat treatment (ICHT) on the evolution of microstructures and mechanical properties in different building height regions of an L-DED TiAl alloy thin-wall sample. The results indicate that ICHT induces discontinuous coarsening (DC) effects by consuming the lamellar interface energy of the initial lamellae, resulting in grain refinement. With the increase in building height, the thermal accumulation leads to an increase in the initial lamellar spacing, which weakens the DC effect. At the top, insufficient thermal cycles prevent fine grain growth and erode coarse grains, hindering overall grain refinement. Ultimately, the hierarchically heterogeneous microstructure forms in the L-DED TiAl alloy, including refinement of hierarchical lamellar colony structure decorated with fine (α2+γ) lamellar structure and (α2+6H-LPS) lamellar structure (6H-LPS refers to 6H long-period structure phase). Specifically, the bottom region exhibits the best combination of ultimate tensile strength (706 ± 33 MPa) and strain (0.68 ± 0.05 %). The high tensile strength can be attributed to the hindrance of dislocation movement by the fine lamellae and the 6H-LPS phase ,caused by the high cooling rate of L-DED, while the elongation is attributed to the reduction in crack propagation energy due to the presence of fine grains.

Performance analysis of a novel single-flywheel resettable-inertia damper with eddy-current damping

The clutching inertia model presents an ideal Bang-Bang control approach, but it is challenging to realize practically through passive means. In this paper, a single-flywheel resettable-inertia damper (SRID) is proposed on the basis of the clutching inertia model. This device is implemented with a rack-and-pinion system, a right-angle gearbox system, and a flywheel-mounted eddy-current damping system. Initially, a mechanical analysis model of this device is established according to its working mechanism. Subsequently, comparative analyses are performed on the performance of SRID in a single degree-of-freedom (SDOF) structure compared to viscous dampers (VDs) subjected to harmonic and seismic excitations. The results show that the SRID can achieve a comparable control effect as VDs with a much smaller need for the damping coefficient, reflecting a damping amplification effect over 100 times. The SRID is effective in controlling peak displacement and absolute acceleration responses, especially for long-period structures. Moreover, the control performance is significantly improved with increasing magnetic induction intensity.

Truncating ground motions using the VMD-Hilbert transform for nonlinear dynamic analyses

Nonlinear dynamic analyses of engineered structures under long-duration ground motions usually require significant computational time, especially when performing incremental dynamic analyses or when developing fragility curves. This study proposes a truncation method of seismic records to reduce the computation cost of nonlinear structural analyses based on the Variational Mode Decomposition and the Hilbert Transform. The truncation-starting and -ending time instants are identified using the relative cumulative spectral energy, which is used to represent the Hilbert spectrum energy variation over time. The effectiveness of the proposed method is verified by the elastic pseudo-response spectrum, three different inelastic single-degree-of-freedom models and a multi-degree-of-freedom system. The proposed method, compared with the Arias intensity-based method, proves to be effective, not only for short-period structures, but also for medium- and long-period structures, allowing for reduction of ground motion duration of about 65% on average.

Microstructures and improved properties of Cu–Mo alloys induced by high current pulsed electron beam irradiation

In this paper, a Cu–Mo alloying layer with improved properties was fabricated by high current pulsed electron beam (HCPEB) irradiation. The microstructure of the modified layer was investigated by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The microhardness and friction properties were also measured. After HCPEB irradiation, nano Mo particles, solid solution, and long-period superlattice structures were generated on the surface of Cu–Mo alloys, together with the formation of defect structures. These microstructures led to a significant increase in the surface hardness. The results of sliding wear tests indicated that the HCPEB-irradiated samples exhibited better properties compared with the initial one, which was attributed to the ultrafine Mo particles and the hardened surface.

Theoretical study of long-range ordered vacancy distribution in two-dimensional boron structures

<sec>In a two-dimensional boron structure, the ordered high-concentration vacancy distribution can enhance structural stability and significantly modulates material properties. Based on recent experimental progress, herein we particularly focus on the two-dimensional boron structures with a striped distribution of hexagonal vacancies, in order to explore the formation of long-period boron structures.</sec><sec>Utilizing the structures of alloy generation and recognition (SAGAR) program developed by our group, we eliminate duplicate structures according to the structural symmetry to reduce computational cost. An effective model system is proposed to investigate the effect of vacancy distribution on the stability of the system, where the interactions between vacancies are utilized for estimating the total energy. By selecting structures with appropriate concentrations and combining first-principles calculations, the parameters in the model are fitted for different vacancy neighbor interactions, which can be further used to predict stable structures at various vacancy concentrations. The feasibility of model analysis is emphasized for structural screening, showing the good agreement between the parameterized model and the first-principles calculations.</sec><sec>Interestingly, under the same vacancy concentration, stable boron structures with different cell sizes exhibit distinct vacancy distributions, indicating a trend of long-period distribution for ground state structures. To address this phenomenon, when the stable candidate structures from the 1/6 series are dominant in number within the computable range and the changes in neighbor statistics can be clearly seen, we select the structures from this concentration series for detailed calculations.</sec><sec>The calculation results indicate that the convergence of the average energy is primarily influenced by the interaction between the fourth nearest neighbor and the sixth nearest neighbor. When considering only these two neighbors, the system energy changes with the increase of cell size as follows: the average energy of structures with a cell size being an even multiple of the minimum cell size keeps unchanged, while the average energy of structure with a cell size being an odd multiple of the minimum cell size gradually decreases, eventually converging to a stable value. When including the interactions between the ninth nearest neighbor and the tenth nearest neighbor, the average energy of structures with a cell size being an even times the minimum cell size also decreases gradually. The average energy decreases with oscillations, with the magnitude gradually diminishing and eventually stabilizing. This discovery reveals that the enhanced stability of long-period structures is attributed to the competitive interactions among different neighboring vacancies.</sec>

Characteristics of earthquake ground motions requiring extended dynamic analysis

ABSTRACT The absolute maximum response (AMR) of structures might occur posterior to the end of earthquake excitations, hence, extending the dynamic analysis to the post-shaking phase is required. This phenomenon was found to be more common for long-period and low-damping structures, which are prevailing in regions of low-to-moderate seismicity like Australia. In this article, the mechanism of the occurrence of AMR in the post-shaking phase is first explained using single-degree-of-freedom (SDOF) systems subjected to a simple sine wave. Further investigation on real earthquake ground motions reveals that whether an extended analysis is required depends greatly on the characteristics of the post-significant duration phase. Finally, suitable metrics for describing ground motions that require extended analysis (EAGMs) are identified based on the Kolmogorov–Smirnov test. Regression analyses are then conducted to predict the probability of EAGMs.

Effect of damping on the seismic response of long-period structures considering crossover phenomena

This study systematically investigates the effect of damping on the seismic response of long-period structures. For long-period single-degree-of-freedom systems, the addition of damping would on average reduce the relative deformation and velocity, but increase the absolute acceleration. However, the crossover phenomena, i.e., the increase of the damping leads to the larger structural response, would occur in the spectral displacement or velocity of some certain ground motions, which is more pronounced with the increase of structural periods. The percentage of ground motions developing crossover phenomena attends approximately 100%, 40% and 20% for the acceleration, velocity and displacement, respectively, at very long structural periods. For long-period multiple-degree-of-freedom systems, illustrated by two cable-stayed bridges, the addition of linear viscous fluid dampers (VFDs) would averagely lead to the reduction of the displacement responses, but the crossover phenomena might also occur. It is recommended that VFDs be implemented to cable-stayed bridges as the deck longitudinal displacement is generally reduced and the deck longitudinal vibration is damped out during a short time compared to the uncontrolled case. However, the damping coefficient of the VFDs needs to be restricted such that the damping force is limited to a reasonable range, and significant response increments of some components are avoided.

Evaluation of the relationships in the tensile plastic deformations and the nano-micro structures of PA6 and PAMXD10 with different thermal histories

Polyamide (PA) is a semi-crystalline polymer in which the main chain is configured by repeating units of amide bonds (NHCO). The strength of PA is achieved by the intermolecular hydrogen bonds between the hydrogen and oxygen atoms of the amide bonds. The thermal history conditions change the crystallization rate and crystalline structure of the PA, which affects its macroscopic mechanical properties. In this study, the relationship between the nano-micro structure of PAs and their macroscopic plastic deformation behavior was investigated. PA6 and PAMXD10 specimens were prepared with different microstructures obtained from two different crystallization processes, called the “isothermal” and “annealing” conditions, respectively. The microstructures were investigated using differential scanning calorimetry, small angle X-ray scattering (SAXS), large angle X-ray scattering and polarized optical microscopy, and the mechanical behaviors were evaluated using uniaxial tensile tests. The maximum stresses of the stress strain curves for PA6 and PAMXD10 increased with temperature under isothermal and annealing conditions. Although the ductility of PA6 and PAMXD10 obtained under isothermal conditions at a higher temperature decreased, both PA specimens obtained under the annealing condition at a higher temperature elongated without fracture across a large strain range. The SAXS measurements revealed that the nano-micro structures of the brittle specimens in PA6 and PAMXD10 consisted of thick lamellae and thick amorphous phases. In contrast, large and small long-period structures co-existed in the specimen obtained under annealing conditions. This indicates that the presence of a composite structure, in which large and small long-period structures are mixed, inhibits the propagation of fractures in the later stages of deformation.

Simplified engineering geomorphic unit-based seismic site characterization of the detailed area plan of Dhaka city, Bangladesh

Severe failure of improperly designed and poorly constructed structures may occur due to the amplified and prolonged ground motion during an earthquake, and hence prediction of the ground motion characteristics at the soil surface is crucial. In this study, based on the prepared simplified engineering geomorphic map, we performed a one-dimensional (1D) nonlinear site response analysis for seismic site characterization of the recently proposed Detailed Area Plan (DAP) area of Dhaka City, the Capital of Bangladesh. The engineering geomorphic unit-based map was prepared from image analysis and verified with the collected borehole data and surface geology map. The study area was classified into three major geomorphic units and seven sub-units subject to the subsurface soil profiles. Nine earthquake time histories, seven from the PEER NGA WEST2 data set and two synthetics, and seven identified subsurface soil profiles were used for nonlinear site response analysis, along with the BNBC 2020 uniform hazard spectrum as the target spectrum. For the selected earthquake ground motions, the near-surface soil response of the DAP area showed de-amplification of acceleration in the short period and amplification of acceleration in the long period. The amplified long-period acceleration could cause severe damage in inappropriately designed and poorly constructed long-period structures. The outcome of this study could be used to prepare a seismic risk-sensitive land use plan for the future development of the DAP of Dhaka City.

Development of high barrier biodegradable poly(butylene carbonate-co-terephthalate)-based blends with balanced mechanical properties by self-reactive compatibility and co-crystallization

Compatibility and crystal structure are the most crucial factors to affect the mechanical properties of blending materials. In this work, dozens of kilogram-scaled biodegradable polyester poly(butylene carbonate-co-terephthalate) (PBCT) have been synthesized by a 150L pilot plant, and successfully prepared a series of PBCT-based blends with excellent compatibility by self-reactive compatibility without any extra compatibilizer. The tensile results illustrated that blending PBCT with these industrial biodegradable polyesters could significantly improve the mechanical properties, including tensile strength and elongation at break. Based on the analysis of molecular weights, thermal properties, rheology behavior, and long-period structure, it was clear that the compatible mechanism of PBCT-based blends conformed to reactive compatibility. Wide-angle X-ray diffraction indicated that the reactive compatibility facilitated the formation of co-crystallization. Thus, the chain segments’ reactive compatibility and co-crystallization behavior simultaneously improve the mechanical properties of PBCT-based blends. In addition, the improvement of barrier properties of PBCT-based blends indicated that PBCT as a blending material would significantly expand the application scope of biodegradable polyesters and reduce the dependence on compatibilizer.

EBSD patterns simulating multilayer twins based on dynamical theory of electron diffraction.

Electron backscatter diffraction (EBSD) can be employed to determine crystal structures but has not been used alone to identify defects at the atom scale due to the lack of understanding of the EBSD patterns generated by various structure defects. In the present work, the EBSD patterns of FCC-Fe with 9-layer, 6-layer and 3-layer twin structures are simulated, respectively, using the revised real space (RRS) method and compared with the counterpart of perfect crystals. Our results show that when the electron beam is incident along a direction parallel to the twin plane, the pattern appears symmetrical with respect to the corresponding Kikuchi band of the twin plane, and the diffraction details within the Kikuchi band also exhibit symmetry with respect to the middle line of the Kikuchi band. Moreover, the overall clarity of the patterns decreases, and the pattern becomes more blurred with increasing the distance from the Kikuchi band corresponding to the twin plane. By contrast, the incident electron beam along the direction perpendicular to the twin plane results in diffraction superposition of the matrix region and the shear region, which shows twofold rotational symmetry with respect to the Kikuchi pole corresponding to the normal to the twin plane. In addition, some extra Kikuchi bands appear in the EBSD patterns due to the long-period structures of the multilayer twins. As the number of multilayer twins decreases, the number of extra Kikuchi bands decreases and the area of the blurring pattern increases. The correlation between twin structures and EBSD patterns provides theoretical insights for identifying twin structures by the EBSD technique.

Construction of novel Cu-α-diimide interactions for enhancing thermal resistance and dimensional stability of polyimide films

The new-generation polyimide films with simultaneously outstanding thermal stability and low coefficient of linear thermal expansion (CTE) are urgently needed. Herein, coordination bonds were employed to improve polyimide films' heat resistance and dimensional stability. Polyimide-Cu complex films were fabricated by incorporating α-diimide units (bidentate ligands) into the BPDA-ODA (the structure of commercially available Upilex-R® polyimide films) backbones. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Energy dispersive X-ray mapping results showed that the coordination interactions occur between α-diimide and copper ions. Wide-angle X-ray diffraction (WAXD) and two-dimensional small-angle X-ray scattering (SAXS) spectra demonstrated that Cu-α-diimide coordination structures introduced in intermolecular chains leading polyimide films transformed from a semi-crystalline state to amorphous state, and inhibited the long-period formation structures. The plateau modulus and longer characteristic relaxation time (τ∗ = 1996.5 s) revealed by dynamic thermomechanical analysis indicated that crosslink networks were successfully formed by constructing coordination bonds. As a result, polyimide films' thermal resistance and dimensional stability were simultaneously enhanced. The typical PI-Cu50 films exhibited elevated glass transition temperatures of 353 °C (pristine PI-Cu0 ∼ 302 °C) and a lower CTE of 47.4 ppm/K (pristine PI-Cu0 films ∼ 64.4 ppm/K) in ranges of 300–400 °C, showing a promising application in the field of high-temperature environments.