Hard Body Impact Research Articles

Full-Scale Assessment of Seismic and Wind Load Performance in the Design of a Flexible Solar-Shading Double-Skin Façade

Cable-supported façades represent a novel approach in the design and technology of double skin façades (DSFs). This type of system not only offers flexibility in terms of exterior finishes, but also regulates the access of solar radiation, thereby transforming the appearance of the building in response to varying daylight conditions. However, the structural performance of these façades under wind, impact, and seismic loads remains an active area of research. The study is a groundbreaking work that experimentally evaluates the wind and seismic behaviour of these type of façades. The methodology used for the evaluation of flexible masonry facades includes laboratory tests analysing the individual capacity of the connections and materials of the system under standardized and non-standardized procedures. A full-scale experimental sub-assembly specimen of a representative module of the façade is also subjected to uniformly distributed pressures of wind load tests, as well as hard body and soft body impact tests. The setup considered the border conditions, tension loads, and actual materials. Furthermore, the earthquake assessment includes tests of full-scale specimens subjected to these demands. The results show up to 30% enhanced performance relative to similar systems reported in the literature. Furthermore, research findings facilitated the refinement and redesign of the system components, thereby validating the DSF case study.

Produção e caracterização de pedra artificial para revestimento com resíduo calcário laminado em matriz polimérica

Abstract Exploiting laminated limestone from Cariri Ceará for ornamental and coating purposes has generated about 2.9 million tons of waste, which is discarded of improperly, making it important to search for alternatives to this material. Thus, this work aims to develop artificial stone for wall and floor coating, using laminated limestone waste (Cariri Stone) and a polyester resin. Initially, Cariri stone waste was characterised, and then artificial stone was made with 25% resin and 75% waste, by volume. Water absorption tests and resistance to compression, flexion, abrasion and hard body impact were performed on the composites produced. The results showed that the artificial stone presented water absorption about 5 times lower and abrasion resistance 448% higher than the natural stone, compressive and flexural strength 38.8% and 72.9% lower than the natural stone, respectively, and energy values equivalent to the commercial natural stone in the hard body impact test. It can be observed that the composite produced has a technical potential for use as a coating in civil construction, after adjusting the production process of the artificial stone.

Energy absorption behavior of bamboo concrete composite wall panel

The use of renewable, natural building materials like bamboo for wall construction has a great advantage over conventional non-green walling materials. The woven bamboo striped cement mortar plastered walling system or Bamcrete panel technology has a great prospect with its eco-friendly nature. For a long time, this has been traditionally adopted in north-eastern regions of India in the construction of ‘Assam type house’. But this wall technology is not been exposed in modern-day construction. It is important to emphasize this technology, hence this research study presents an experimental study of energy absorption characteristics of Bamcrete panel under the impact and monotonic loading conditions to highlight the possible improvement of the traditional Ekra wall of Assam type house based on different parametric variations in the fabrication of panels like framing options, type of bamboo species, panel weaving technique, and panel casting using different design mix mortar at different strengths were studied. The standard BS: 5234–2:1992 [1] was followed to carry out the small hard body impact test and static load test in the constructed Bamcrete partition panels. The variation of bamboo species does not affect significantly in the energy absorption capacity of Bamcrete panels and the impact resistance of panels increased significantly using design mix mortar compared to the traditional mason mix mortar.

Comparison between Synthetic and Biodegradable Polymer Matrices on the Development of Quartzite Waste-Based Artificial Stone

The development of artificial stone from the agglutination of polymeric resin using industrial wastes can be a viable alternative from a technical, economic, and sustainable point of view. The main objective of the present work was to evaluate the physical, mechanical, and structural properties of artificial stones based on quartzite waste added into a synthetic, epoxy, or biodegradable polyurethane polymer matrix. Artificial stone plates were produced through the vacuum vibration and compression method, using 85 wt% of quartzite waste. The material was manufactured under the following conditions: 3 MPa compaction pressure and 90 and 80 °C curing temperature. The samples were characterized to evaluate physical and mechanical parameters and microstructure properties. As a result, the artificial stone plates developed obtained ≤0.16% water absorption, ≤0.38% porosity, and 26.96 and 10.7 MPa flexural strength (epoxy and polyurethane resin, respectively). A wear test established both artificial quartzite stone with epoxy resin (AS-EP) and vegetable polyurethane resin (AS-PU) high traffic materials. Hard body impact resistance classified AS-EP as a low height material and AS-PU as a very high height material. The petrographic slides analysis revealed that AS-EP has the best load distribution. We concluded the feasibility of manufacturing artificial stone, which would minimize the environmental impacts that would be caused by this waste disposal. We concluded that the production of artificial rock shows the potential and that it also helps to reduce environmental impacts.

Small Hard Body Impact on Annealed, Heat Strengthened and Fully Tempered Laminated Glass

Neglecting the accidental soccer or golf ball hitting the window of the neighbors in a movie, actual impact on glass is rare. In architecture, the only significant case in the literature is where a fully tempered laminated panel of the New York Apple cube was hit by a small stone launched by a snow blower. Nowadays a lot of glass is used in sound screens next to high ways. These are however subjected to regular impact of small, fast-moving hard bodies. Mostly small stones which are removed from the asphalt road surface due to wear and are launched by car tires. This is a regular occurrence leading to safety questions and also to considerable cost as replacing the sound screen panels not only costs money but also requires closing down at least the outer lane of the highway, thus reducing the traffic flow. Thus a study was made of the impact resistance of annealed, heat-strengthened, and fully tempered laminated glass using test panels. This was followed by the testing of a full-size sound screen panel. The results show that the impact resistance of tempered glass is determined by the amount of compressive surface pre-stress. However, it is also noted that although fully tempered glass better resists impact, it has no residual strength after an impact with the critical energy.

Exploratory Finite Element Analysis of Monolithic Toughened Glass Panes Subjected to Hard-Body Impact

The paper reports the results of an extensive experimental campaign, in which simply supported toughened glass samples with dimensions of 500 × 360 mm2 and three thicknesses (6, 8 and 10 mm) were subjected to hard-body impact. A steel ball (4.11 kg) was released from different drop heights, starting from 10 cm above the sample and increasing by 10 cm in each step until glass breakage occurred. In this way, for all samples a critical drop height (causing fracture of glass) was determined. Experiments were carried out for 35 samples for each thickness; thus 105 samples were tested in total. A 3D numerical model of the experimental setup was developed using the commercial finite element analysis (FEA) software ABAQUS and Implicit Dynamic solver. The numerical study was aimed at numerical reproduction of the experiments and determination of the maximum principal stress in the glass that occurs during the impact. To reduce the number of FEs and increase the computational efficiency of the simulations, only a quarter of the nominal geometry with appropriate boundary conditions were modelled. The simulations were performed for a given weight of the steel impactor, glass thickness and the corresponding critical/breaking drop height found in the experimental campaign. In this way, an impact strength of the toughened glass was retrospectively evaluated. The simulations were used to investigate the impact history in terms of stress in glass, acceleration and velocity. Moreover, the resulting history of impact force was determined.

An investigation of impact resistance capacity of polypropylene (PP) added plasterboard subjected to soft-body impact

Plasterboard is one of the most-commonly used construction materials because of its low cost and easy installation characteristics. Although the low strength and fragility make plasterboard functioned as non-load-bearing components. Plasterboard walls are always required to satisfy impact resistance against impact from accidental body strike, hard-body impact from wheelchair, etc. during its usage. This study investigates the impact resistance capacity of plasterboards being subjected to soft-body impact load. Laboratory sandbag impact tests are conducted to examine the responses of plasterboard and PP fibre strengthened plasterboard system at different velocities. Detailed numerical models of plasterboards are also generated to assist the analysis. Different damage and failure modes are observed on the plasterboards when subjected to impactor strike at different velocities. It is found that the coupled deformation of plasterboard and sandbag leads to different impact load time histories from sandbag soft impact, which results in the different failure modes. The PP fibre strengthened board exhibits better impact resistance than conventional plasterboard. Parametric study is then conducted to quantify the peak central deflections under different strength and thickness variances on plasterboard. An empirical formula is then derived based on the parametric results for preliminary assessment of the plasterboard impact resistance capacity.

Nonlinear analytical study of structural laminated glass under hard body impact in the pre-crack stage

Emerging glass structures, which frequently use laminated glass (LG) as load bearing elements, see a significant rise in recent decade. Existing analytical solutions for LG under impact present limitation when introduced into structural LG products, as structural LG having more glass plies and soft polymeric interlayers requires more accurate nonlinear analytical model. In this study, a nonlinear analytical model was proposed for the simply supported square structural LG subjected to hard body impact. The motion equations were established based on a third order shear deformation theory and von Kármán nonlinear strain–displacement relationship. Based on a two-step perturbation method, the solutions of the motion equations were obtained. The fourth-order Runge–Kutta method was used to capture the impact force variation. Drop weight impact tests with increasing impact velocity, were conducted to record the impact force of LG panels before breakage. Eighteen LG panels with PVB or SG interlayers were tested. Through analysing the fracture initiation from high speed photos as well as the impact force variation in the impact attempt causing fracture, certain feature of the experimental impact force response was determined to be validated with analytical prediction. The validation results show that the proposed model can well reproduce the examined feature and achieve satisfactory impact force response. Case study was then designed to investigate the influence due to the safety windows film on reducing the pre-crack impact response. The effective thickness of LG based on the equivalence of indentation was also proposed for the hard body impact.

Experimental and analytical study on the pre-crack impact response of thick multi-layered laminated glass under hard body impact

This study presents a combined experimental and analytical study on the impact response of multi-layered laminated glass (MLG) under low-velocity hard body impact before glass breakage. The drop weight impact tests using repeated attempts with increasing impact velocities were firstly performed on 12 MLG panels with double PVB or SG interlayers to record the impact response, high speed fracture process. The experimental results identify that: (1) the indentation is the predominant factor for glass fracture in the examined impact scenarios; (2) the key time interval of the pre-crack impact response is within 0.6 ms. The indentation which hasn't been considered in the existing analytical works was hence introduced into the proposed nonlinear analytical model, which employed third order shear deformation theory and obtained the solutions of motion equations by a two-step perturbation method, according to the former finding. The calculated impact response based on the proposed model was validated with the experimental results within 0.6 ms based on the latter finding and showed satisfactory agreement.A parametric study was subsequently conducted to investigate the influence of factors such as the number of glass layers, glass thickness and ratio, panel size on the pre-crack impact response. The results show the increase of peak force and indentation is more sensitive to the increase of total glass thickness after the thickness reaches 24 mm and presents less sensitivity when the thickness approaches 57 mm. The variation of the glass thickness ratio has no influence on the pre-crack behavior once the total glass thickness is fixed.

Experimental mechanical analysis of traditional in-service glass windows subjected to dynamic tests and hard body impact

The large use of glass in buildings, and especially the presence of fenestrations and facade systems, represents a potential critical issue for people safety. The brittle nature of glass (with limited elastic deformation and resistance) is often enforced by its use in combination of several secondary components, whose reciprocal interaction and potential damage should be properly assessed. In the case of windows, accordingly, a special care should be spent for glass members but also for the framing system and possible adhesive or mechanical connections. This study aims at exploring the dynamic response and damage sensitivity of traditional glass window systems, based on the experimental derivation of few key material properties and mechanical parameters. To this aim the attention is focused on traditional, in-service windows that belongs to existing residential buildings and are typically sustained by timber frames, through a linear flexible connection. In doing so, major advantage is taken from experimental analysis, both in the static and dynamic field, for whole window assemblies of single components. For comparative purposes, selected window specimens including plastic (PVC) frame members and Insulated Glass Units (IGUs) are also taken into account in the paper. The static characteristics of the windows components are first preliminary derived. The dynamic performance of such a kind of systems is then experimentally explored with the support of modal analysis techniques and hard body impact procedures, including the experimental derivation of stiffness parameters for the frame members and the glass panels. Further assessment of experimental outcomes is finally achieved with the support of Finite Element numerical analyses.

Static and dynamic measurements on glass panes – experimental analysis

The paper presents testing of glass panels, static test and dynamic test by hard body impact. Pendulum test is presented. Test procedure is described as well as tested samples and their material characteristics. The glass type of tested samples were laminated and float glass, as well as the age of the glass samples were different.

Resistance of External Thermal Insulation Composite Systems with Rendering (ETICS) to Hail.

This paper analyzes the resistance to hail of external thermal insulation composite systems (ETICS), i.e., external thermal insulation of foamed polystyrene with the same finishing coat and various reinforcing mesh and base coats used to make the reinforced layer. The manuscript presents our own new method for assessing ETICS resistance to hail and test results obtained according to this method. The basic premise of the presented new research methodology is evaluation of the thermal insulation system surface damage and fracture toughness, in the function of hit velocity with a polyamide ball with a standardized diameter and weight. The results of hail resistance tests were compared with the values of hard body impact resistance obtained in the tests done according to ETAG 004. Results obtained by the new method help to evaluate precisely the resistance of thermal insulation sets to damage as a result of impact of heavy objects of permanent shape, with greater accuracy than the hard body impact test. They also confirmed that thermal insulation sets with dispersion adhesive in the reinforcement demonstrate greater resistance to damage as a result of hail impact than the sets with cement-based adhesives and that weight of the reinforcing mesh used in the system is not significant to affect the hail resistance.

An adhesively-bonded cast glass system for the Crystal Houses façade

Chapter 4 provided an overview of the three structural systems utilizing cast glass components in architecture, including a brief overview of the work presented in this dissertation. This chapter presents the design principles and experimental work for the first of the two systems explored in this work: a transparent, adhesivelybonded glass block system designed for self-supporting envelopes. The proposed system was developed for the Crystal Houses facade in Amsterdam, designed by MVRDV Architects. The system is exclusively constructed by solid cast glass blocks, bonded with DELO Photobond 4468, a colourless, UV-curing adhesive. This allows for a system of an increased transparency, sparing the necessity of an opaque substructure. In contrast with previous realized projects, solid soda-lime glass blocks are used rather than borosilicate ones. Initially, several architectural prototypes, comprising glass elements of different tolerance ranges, are built to evaluate the visual performance and the thickness of the adhesive that allows for an even spread. The prototypes indicate that a homogeneous bond thicker than 0.3 mm cannot be obtained by the selected adhesive due to the latter’s flow properties and low viscosity. Based on the adhesive’s optimum application thickness, it is determined that the glass blocks’ top and bottom surfaces should be flat within 0.25 mm for guaranteeing an even adhesive layer of the highest strength. The structural verification of the system is demonstrated by physical testing of prototypes in compression, 4-point bending, hard-body impact and thermal shock. Compressive tests on individual blocks highlight the need for proper detailing and uniform load distribution of the system. Compressive tests on columns made of adhesively bonded glass blocks further confirm that strict size tolerances are essential for maximizing the load-bearing capacity of the system: specimens with larger size deviations fail in considerably lower stress values than specimens with smaller size deviations. Furthermore, series of 4-point bending tests on adhesively bonded glass beams demonstrate that the chosen adhesive enables the glass brick wall to behave monolithically under such loading when the adhesive is applied in a constant layer of the optimum thickness. Overall, the results show that the adhesively bonded glass block structure can provide the required structural performance, but only if strict tolerances are met in the geometry of the glass blocks so that the chosen adhesive can be evenly spread in a constant thickness.

Experimental investigation into the post-breakage performance of pre-cracked laminated glass plates

SentryGlas® (SG) laminated glass (LG) is commonly used as a load bearing material in structural applications. Like other conventional structural materials, SG LG plates are expected to have adequate stiffness and resistance to breakage so that they can withstand loads from either external action or their self-weight. This paper reports an experimental study of the post-breakage behaviour of SG LG plates. In the study, a weight-drop impact load was first applied to crack glass plates to create a crack pattern under hard-body impact. These cracked glass plates were subsequently subjected to a continuous static load until collapse. The applied load and the deflections at seven reference points on the specimens were recorded and examined. Two key parameters, the initial stiffness and the peak post-breakage resistance, were identified to evaluate the post-breakage performance of seven groups of specimens. The effects of glass make-up and the support condition were observed and are discussed. It was found that the support condition determines the load transfer path and further influences the ‘yield line’ pattern and post-breakage resistance. It was also observed that the different crack patterns created various load bearing mechanisms and the glass make-up also played an important role in the post-breakage resistance and the failure mode. Experimental results reveal that the annealed glass (ANG) sheet yields the highest initial stiffness and resistance in the post-breakage phase. With an increasing number of SG interlayers, the LG plate is more likely to be penetrated before the ‘yield lines’ completely form. Finally, a comparison study was carried out to investigate the post-breakage performance. Results indicate that in comparing ANG and the fully tempered glass (FTG) plates, the former exhibits a better ability in retaining the post-breakage capacity.

An adhesively-bonded cast glass system for the Crystal Houses façade

Chapter 4 provided an overview of the three structural systems utilizing cast glass components in architecture, including a brief overview of the work presented in this dissertation. This chapter presents the design principles and experimental work for the first of the two systems explored in this work: a transparent, adhesivelybonded glass block system designed for self-supporting envelopes. The proposed system was developed for the Crystal Houses façade in Amsterdam, designed by MVRDV Architects. The system is exclusively constructed by solid cast glass blocks, bonded with DELO Photobond 4468, a colourless, UV-curing adhesive. This allows for a system of an increased transparency, sparing the necessity of an opaque substructure. In contrast with previous realized projects, solid soda-lime glass blocks are used rather than borosilicate ones. Initially, several architectural prototypes, comprising glass elements of different tolerance ranges, are built to evaluate the visual performance and the thickness of the adhesive that allows for an even spread. The prototypes indicate that a homogeneous bond thicker than 0.3 mm cannot be obtained by the selected adhesive due to the latter’s flow properties and low viscosity. Based on the adhesive’s optimum application thickness, it is determined that the glass blocks’ top and bottom surfaces should be flat within 0.25 mm for guaranteeing an even adhesive layer of the highest strength. The structural verification of the system is demonstrated by physical testing of prototypes in compression, 4-point bending, hard-body impact and thermal shock. Compressive tests on individual blocks highlight the need for proper detailing and uniform load distribution of the system. Compressive tests on columns made of adhesively bonded glass blocks further confirm that strict size tolerances are essential for maximizing the load-bearing capacity of the system: specimens with larger size deviations fail in considerably lower stress values than specimens with smaller size deviations. Furthermore, series of 4-point bending tests on adhesively bonded glass beams demonstrate that the chosen adhesive enables the glass brick wall to behave monolithically under such loading when the adhesive is applied in a constant layer of the optimum thickness. Overall, the results show that the adhesively bonded glass block structure can provide the required structural performance, but only if strict tolerances are met in the geometry of the glass blocks so that the chosen adhesive can be evenly spread in a constant thickness.

Experimental investigations into SGP laminated glass under low velocity impact

The structural use of laminated glass (LG) is growing rapidly. To meet safety and post-breakage strength requirements, a SentryGlas®Plus (SGP) interlayer has been widely used in LG. Limited data has been available to date concerning the impact resistance of SGP LG. This paper describes an experimental investigation into the damage behaviour of SGP LG panels under hard-body impact. A mean minimum breakage velocity (MMBV) test approach has been employed to determine the breakage energy. By tracing the crack initiation through the use of high speed filming, six categories of breakage sequence have been classified. The characteristics of crack propagation, including the lagging time between the initiation of different cracks and the typical crack propagation speed, were also obtained. This is followed by the identification of the representative cracking morphology and the motion behaviour of the impactor. The impact resistance of SGP LG has been calculated by examining the effects of the design variables such as the LG panel size, interlayer thickness, the support conditions and the glass make-up. It was found that the influence of LG panel size on the MMBV and both pre- and post-breakage stiffness is limited, and increasing the interlayer thickness cannot improve the resistance to glass breakage under impact. The LG panel with clamped edges requires more MMBV to trigger glass breakage and has an increase of 44% in pre-breakage stiffness compared to the panel with bolted connections at four corners. The evident improvement in post-breakage stiffness due to the beneficial fragmentation pattern of heat strengthened (HS) glass, compared to its counterpart of fully tempered (FT) glass, has also been revealed. However, the differences in MMBV between them are modest. Results also indicate that a significant degradation of dynamic stiffness in the post-breakage stage can be found in both the double layered LG with thicker interlayer, and in the triple layered LG. The energy dissipation behaviours were also examined, and results suggest that the energy dissipation ratio can be greater than 40% in most instances, and the thicker interlayer will produce negative effects on dissipating impact energy. Two types of delamination are identified, and the dependency of their delamination growth on the impact velocity is analysed.

Experimental Study of Multiple Layered SGP Laminated Glass under Hard Body Impact

Experimental Study of Multiple Layered SGP Laminated Glass under Hard Body Impact

Impact resistance of external thermal insulation systems

In the paper the results of an experimental program intended to determine factors influencing the impact resistance of the External Thermal Insulation Composite Systems (ETICS) were presented. For the research the systems based on polystyrene have been chosen. The insulation material was faced with a rendering consisting of base coat reinforced with standard or armored glass fibre mesh and silicone or silicone-silicate binders as finishing coats. The influence of various renderings components was evaluated with respect to resistance to hard body impact and resistance to hail. The test results were discussed in the context of the possible impact level on ETICS in use.

Modelling impact fracture and fragmentation of laminated glass using the combined finite-discrete element method

Fracture and fragmentation responses of laminated glass under hard body impact are modelled with the combined finite-discrete element method (FEM-DEM). The method is essentially a discrete element method with finite element mesh be embedded in, yielding more accurate contact forces as well as mass and energy conservation. Failure models of glass, interlayer and glass-interlayer interface are discussed respectively and proven to be reliable in simulating the rupture of laminated glass. Numerical examples are presented and validated with results from different sources, and the advantage of the FEM-DEM modelling on the impact failure of laminated glass over its parent FEM and DEM is demonstrated. The influences of Young's modulus of interlayer are further discussed, showing that a stiff resin can effectively improve the deformation performance at little expense of energy absorption. In general, modelling the impact failure of laminated glass using the combined finite-discrete element method is successful.

A comparative study of numerical modelling techniques for the fracture of brittle materials with specific reference to glass

This paper presents a comparative study on the available numerical approaches for modelling the fracturing of brittle materials. These modelling techniques encompass the finite element method (FEM), extended finite element method (XFEM), discrete element method (DEM) and combined finite-discrete element method (FEM/DEM). This study investigates their inherent weaknesses and strengths for modelling the fracture and fragmentation process. A comparative review is first carried out to illustrate their fundamental principles as well as the advantages for the modelling of cracks, followed by the state-of-the-art trial application in the example cases. An example of a glass beam subjected to low velocity hard body impact is examined as a plane stress problem. By evaluating the applicability of different models, the most desirable model for the entire dynamic fracture response is identified, and this is found to be the FEM/DEM. The FEM/DEM model is further examined by comparing results with the experimental data from high velocity and oblique impact tests. The study reveals that the FEM/DEM yields the most satisfactory results when modelling the dynamic fracture process of brittle materials such as glass.