Investigating the impact resistance of E-glass/ Polyester composite materials in variable fiber-to-matrix weight ratio composition

Abstract

E-glass/polyester composite is formed by combining E-glass fiber as reinforcement with a polyester resin matrix. These constitute materials have different properties from the composite they built. The fiber mat with 65, 55, and 35 weight percentages and a matrix with weight percentages 35, 45, and 65 have been prepared. In each composition reinforcement, the test samples are modeled using Ansys ACP—pre and fabricated using the hand-layup technique. By setting three test samples for each class of composition, a total of nine test samples are prepared. Impact tests are conducted on each test sample using an Izod impact testing machine and using Ansys explicit dynamics numerically. The maximum mechanical properties are obtained in 65 by 35 fiber-to-matrix ratios of the composite experimentally and numerically when compared with the other stated composition. Results of the numerical analysis show that good mechanical properties can be achieved using balanced and compatible reinforcement with the matrix in the composite.

Keywords:

• Composite material
• Impact properties
• E-glass/polyester
• FEM
• Izod impact test
• Resin

Public Interest Statement

Nowadays, there is an increased demand for the use of a lightweight and strong functional composite structure to replace the existing conventional materials. As a structural material E-glass/polyester composites are widely used for many applications. In recent days, fiber-reinforced composites with variable fiber and matrix have been used to robust the strength performance of composite structures. In this article, the impact resistance capabilities of E-glass/polyester with variable fiber-matrix weight ratios are carried out.

1. Introduction

Nowadays, it is commonly observed that most manufacturers are fussing to produce failure-resistance materials to meet the needs of their customers. However, the main challenge remains to find strong and lightweight materials with minimal cost for different structural parts. This is because most manufacturing industries use conventional materials as raw materials to produce various components.

Using conventional materials to manufacture structural parts have many disadvantages, such as higher weight, lower wear, fatigue, and impact resistance. Due to such undesirable material properties, parts fail catastrophically while working. Therefore, to overcome such kinds of problems, evaluating the effectiveness of alternative materials, such as composite materials, that allow overcoming the drawbacks of conventional materials is vital for engineers and manufacturers.

High impact resistance and strong materials provide better guarantee during many work activities of the system by maintaining each part of structural strength (Ferdous et al., 2021). Therefore, composites are preferred for impact loading and structural applications (Kowshik et al., 2022). These materials are developed by combining two or more materials in an appropriate weight ratio and orientation angle (Vaghasia & Rachchh, 2018).

Composite materials consist of reinforcement and matrix. The reinforcement may be synthetics or natural fibers (Muneer Ahmed et al., 2021). These constituents have different properties with each other and within the composite. In particular, natural fibers are very important in terms of their abundance, renewability, environmental richness, biodegradability, and better economy (Balaji et al., 2022; AL-Oqla 2021; Uma Devi et al., 1997).

Natural and synthetic fiber composites are used to enhance the overall properties of the material and innovate new-generation materials (Prabhu and Balaji et al., 2022). Moreover, hybrid composites can improve strength properties for structural applications (Prabhu et al., 2021). Its durability and its good mechanical properties, when compared to conventional materials, are its primary manifestations (Eslami et al., 2015; Prabhu et al., 2022).

Composite structures have been used for a variety of structural applications in various industries, such as automotive, aerospace, sporting goods, and home appliances (Hiremath et al., 2021). In many industrial applications, polymeric-embedded composites are widely preferred as an alternative substitute for conventional materials (Bdaiwi, 2018; Panciroli & Giannini, 2021). Fiber composites are particularly important for lighter and highly stiffened applications (Duflou et al., 2014; Gopinath et al., 2014).

Currently, automotive experts need to produce zero-emission and lightweight vehicles. One of the essential reinforcements for such applications was E-glass fiber (Esnaola et al., 2016). It is less expensive and easily available and critical for enhancing the properties of the matrix (Singh et al., 2013). The addition of glass fibers to various matrices leads to lower density and improved mechanical properties of the composite (Rachchh & Trivedi, 2018). But the oversensitivity of E-glass/polyester composite to impact damage even at lower impact energy and speed during the manufacturing process, and maintenance activities were the major disadvantages. Moreover, matrix cracking and delamination of the composite layers are caused by low-velocity impact (Bhagavathiyappan et al., 2020). Therefore, to overcome such limitations, it is desirable to conduct more investigations on glass fiber-reinforced composite materials.

A balanced and moderate amount of matrix and fiber reduces brittleness properties and increases various damage-resistant abilities. This could be achieved through the right proportion of matrix and filler materials during composite fabrication.

Different researchers have studied the failure properties of the composite under low-velocity impact loading by performing experimental, analytical, and numerical simulations (Zouggar et al., 2016). Kurzawa et al. (2020) investigate the effects of impact on a composite structure with thirty and forty percent fiber volume. Long propagation cracks and fragmented surfaces were observed on the specimen. This is due to the incompatible combination of fiber and matrix in the composite (Claus et al., 2020).

In addition, Shahzad (2011) studied the impact behavior of hemp and fiberglass composite. As can be seen from the result, when eleven percent of the hemp fiber was replaced with glass fiber, the damage tolerance was exceeded. This implies that better strength properties are achieved in a hybrid composite of natural and synthetic fibers than only in a natural fiber composite (Bhoopathi et al., 2017).

Her and Liang (2004) conducted a study on composite structures using Ansys/LS-Dyna computational software. The affluence of different variables, like impact velocity, shell curvature, and boundary conditions was determined. Their result conveyed that higher stiffness leads to greater contact force and lower deflections. Similarly, Bhagavathiyappan et al. (2020) investigated the impact characteristics of various composite materials by executing structural analysis subjected to impact loading conditions. The result shows that unidirectional E-glass/Epoxy has the lowest strain energy of 10 different composite materials. Suresh et al. (2021) investigated experimentally and numerically the drive shaft for automotive applications considering five different chopped-strand glass fibers and they showed that half a percent of the composite shaft can withstand static loads. Moreover, Kostopoulos et al. (2002) investigated the damage from impact loading for motorcycle helmets with glass, Kevlar, and carbon fiber composites. The result shows that Kevlar fiber has good impact-resistant regardless of cost. Besides this, Patnaik et al. (2012) evaluated the mechanical properties of composite materials using variable weight percentages of reinforcement. Their results show that the higher the fiber content, the higher the strength properties. But the disadvantage of the increased amount of fiber content in a composite is increasing the delamination probability (Liao & Liu, 2018).

Panse and Nagayach (2016) conducted impact analysis on two composite materials, Kevlar 149 and graphite, to evaluate the deformation and stress with an explicit dynamic solver for the striking of 8 mm thick armor with a bullet velocity of 928 m/s. The result shows that graphite has higher impact resistance compared to Kevlar 149. Irfan et al. (2015) performed an experimental and numerical investigation to determine the damage behavior of glass fiber-reinforced composites subjected to low-velocity impact. The difference between the numerical and experimental results is very small and appears as the expected state and their conclusion assures that the thickness of the composite laminate determines the deflection of the structure. Also, Alwan et al. (2010) determined the damping characteristics of the composite shafts by analyzing the different frequency levels. As observed from the result, the stiffer shafts could be produced by adding layers in a transverse direction where the composites are boron/epoxy and the smallest frequencies are observed. Similarly, Gao et al. (2015) investigated an adhesively bonded cant lever beam subjected to three different low-velocity impacts. The bonded area of the material was the main location of maximum strain energy, and this is cited as the main reason for the occurrence of higher strain energies and higher equivalent stresses in the final stage. Therefore, this stress concentration area and impact location can lead to catastrophic failure and reduced load-bearing capacity (Sutherland & Guedes Soares, 1999).

On the other hand, Nunes et al. (2004) investigate the damaged area of E-glass/ epoxy composite for ballistic impact application. The result shows that the ballistic performance was determined by the delamination ability of the composite structure. Sivasaravanan and Bupesh Raja (2014) experimented with hybrid epoxy/Nano—clay/glass fiber using Izod and Charpy impact testing machines, and the impact strength capabilities were determined. Finally, as observed from the result, the weight percentage of nano-clay is the main determinant of the composite materials and when it is increased to ten percent, the impact strength decreased and the material is easily delaminated. Cheon et al. (1999) determined the impact energy absorption capacity of hybrid glass fiber reinforced epoxy using the instrumented Charpy impact test and compared the energy absorption strength of pure glass fiber/epoxy to the hybrid composite. Similarly, Raj Kumar et al. (2019) Investigate passenger vehicle bumpers to optimize impact energy by developing composite models using steel and glass fiber reinforcement based. The result shows that glass fiber-based composites are preferable. On the other hand, Abdel-Nasser et al. (2017) evaluated the ballistic velocity threshold using different laminate layers numerically by modeling two different composite materials. From their observation, material properties and layer orientations are the fundamental factors in ballistic impact resistance. Rama Subba et al. (2015) determined the ballistic performance of E—glass fiber reinforcement with a phenolic resin matrix. From the result, the indirect relationship between the laminate thickness and the impact speed was observed.

Overall, the summary of existing studies indicates the presence of various studies conducted for different composite materials related to impact resistance. Some of them focus on the humidity effect under impact load conditions (Alawsi et al., 2009). The others also investigate the impact behavior of composite materials subjected to various parameters, like thickness, laminate order, stacking sequence, orientation angle, and even different variable compositions. The findings from these studies provide insightful evidence about the issues under the study. Therefore, for this study, it is better to refine the composite contents differently and work on a new route to obtain persuasive results. In addition, the concentrations used in this study have not been included so far, and to construct a sufficient understanding of the behavior of composite materials for structural application, it is critical to conduct a study on E-glass/polyester composite using different fiber weight matrix ratios, which are not well investigated so far. With this in mind, the main objective of this study is to explore and identify the correct fiber-to-matrix weight ratios (fiber and matrix contents) in a composite regarding impact strength in a structural application. Thus, knowing the correct and balanced contents of fiber and matrix in the composite leads us to develop a strongly adhered and delamination-free composite structure. This enables the automotive industry to produce various structural components using E-glass/polyester composite for practical use.

2. Material and method

2.1. Materials

The linear long-chain polymers dissolved in vinyl monomers give polyester resin. It has densities of 1.1–1.43 g/cm³ with a glass transition temperature of 70–120°C and good mechanical properties, corrosion resistance, low weight, and less costly are the main features of polyester resin. It is mainly used for chemical, marine, electrical and automotive applications.

Glass fibers are processed from bulk glass and are mainly obtained from a mixture of molten limestone, dolomite, paraffin, and quartz sand, and the main component is silica (Yi et al., 2017). It is used mainly to enhance polymer. For structural applications, E-glass fiber is preferred in various industries. The choice of E-glass fiber as an appropriate material among the list of fiber reinforcements is conducted considering various measures. For instance, compared with other materials, it is available in multiple forms. Furthermore, it also has good strength properties and lower cost with considerable performance (Indira Prasanth et al., 2020). For the numerical analysis, the maximum stress failure criterion was applied. It is extensively used and is simple. As such, each stress on the material must be less than the respective strength of the given material (Echaabi et al., 1996). Table 1 presents the mechanical properties of various types of glass fiber families. It is adopted from (Morampudi et al., 2020) for comparison of our results with the strength properties of E-glass fiber and compliance with the maximum failure criteria

Table 1. Mechanical properties of glass fibers (Morampudi et al., 2020)

Types of glass fiber	Density(g/cm^3)	Maximum strength (Gpa)	Young’s modulus (Gpa)
E-glass	2.58	3.445	72.3
C-glass	2.52	3.31	68.9
D-glass	2.12	2.415	51.7
S-glass	2.46	4.89	86.9
A-glass	2.44	3.13	68.9

2.2. Methods

The study was conducted using experimental testing of glass fiber-reinforced polyester composite and finite element simulation subjected to impact loading. To obtain better mechanical properties the direction of fibers in the matrix kept suitable (Blumentritt et al., 1975). To do this firstly, an E-glass fibers mat was obtained from world glass fiber Ltd in Addis Ababa Ethiopia and the unidirectional lamina of the E-glass fiber mat (200 × 200 × 0.5 mm) are laminated using the hand layup method. Figure 1 shows the E-glass fiber mat as ready for lamination.

Figure 1. E-glass fiber mate.

Similarly, polyester resin, hardener, and wax were obtained from world glass fiber Ltd. To create a laminated structure we first prepare polyester resin as a matrix, Trim Ethylhex Methylene Demine hardener, and mold releasing agent of miracle gloss V₃. The hand lay-up technique was used for the specimen preparation processes due to its cost and ease of processing (Morampudi et al., 2020). To apply the hand layup method, we start by cutting the reinforcement to the mold size as shown in Figure 1 and prepare the matrix by mixing the resin with the activator (hardener) in a 10:1 ratio. Then, we apply a mold release agent (wax) by smearing it on the surface of the mold to facilitate the removal of the developed structure. Then, using the rule of the matrix (RoM), the sum of the weight fraction of reinforcing material (w_f) and matrix material (w) of the composite is equal to the total weight of the composite (w_c).

(1) $w_c=w_f+w_m$(1)

Maintaining the correct fiber matrix weight ratio as 65/35, 55/45, and 35/65 and using these concentrations help us to reduce material costs. Since resin is more costly, it could be balanced with the required fibers. Moreover, testing these ratios and knowing the right fiber-to-matrix ratio enable us to reduce the weight, and brittleness of the composite and create strong adhesion between the laminates. In addition to this, as we review different works of literature which are studied on contents of fiber and matrix in a composite so far, most of them are works on the same fiber and matrix composition such as 50% fiber and 50% matrix and some of the other also works with 60 by 40 fiber and matrix, respectively. Salgar et al. (2017) studied composite structure by maintaining 40%, 50%, and 60% fiber composition. However, it was costly due to more matrixes being required. Therefore, by considering the above points, our study focuses on 35%, 55%, and 65% of fiber composition that have not been investigated so far. The following Figure depicts the hand-layup process for fabricating of test specimen using the above weight ratios. As observed in Figure 2, the mold-releasing agent was painted to the mold and we apply the matrix and fiber successively over the surface of the mold until the required size of the specimen was attained. Following this, 50 tone load was applied over the composite inside the mold and cured for 2 and a half days.

Figure 2. Hand lay-up technique.

For an explanation, the fiber-to-matrix weight ratio can be represented as A, B, and C, respectively. To clearly show the procedures followed to conduct this study, Figure 3 presents the summary of the methods employed in our study.

Figure 3. Methodology of the study.

As shown in Figure 4, the composite laminate in the mold during the curing process. After complete curing, the upper and the lower molds are removed to release a single composite structure.

Figure 4. The curing process of composite material.

2.3. Impact test set up and experiment

The test was conducted using ASTM D256 standard impact testing machine with the specification of a pendulum failing height of 0.0204 m, failing angle of 120°, and striking (impact) velocity of 3.8 m/s. The impact specimens are sized following the given standard with a length, width, and thickness of 65 mm, 12.5 mm, and 3 mm, respectively with a “V”- notch of 2 mm deep at 45° angle. Three test specimens were prepared for three fiber-to-matrix weight ratios each, and the test was conducted on a total of nine impact specimens using an Izod impact testing machine. Figure 5(a) presents the impact test specimen geometry and (b) the composite specimen tested. With this test sample in the Izod impact test machine (c) the dial indicator shows the impact energy values of the test specimen.

Figure 5. Test sample geometry (a), the composite test specimen (b), and the Izod impact tester machine (c).

3. Results and Discussion

In this section, we present and discuss the main findings of our study.

As observed from the Izod impact test result, we understood that E-glass/polyester composites are suitable for structural applications with optimal performance. Furthermore, good mechanical properties were achieved with increased fiber content in the composite but this can lead to brittleness and delamination behavior of the materials (Salgar et al., 2017).

At fiber-to-matrix weight ratios of 65/35, the impact energy values of samples 1, 2, and 3 are 11.7, 13.6, and 12.4 Joule, respectively with average values of 12.6 Joule. Similarly, for 55/45 composition, the impact energies of samples 1, 2, and 3 are 10.3, 10.8, and 11 Joule respectively with average values of 10.7 Joule, and for 35/65 composition 10.8, 9.6, and 10.1 Joule of impact energies are obtained for samples 1, 2 and 3, respectively and 10.17 Joule of average values.

As can be seen from the impact energy values obtained from testing 65/35, 55/45, and 35/65 fiber-to-matrix weight ratios, each sample has approximately similar values and the impact damage resistance abilities are as efficient as required for practical use. However, the weight ratio of 65 by 35 fiber-matrix content has an appreciable impact on energy absorption compared to the other stated weight ratio of composite materials. Table 2 presents the respective impact energy absorption values of each specimen with their average weight ratio.

Table 2. Impact test result

Contents of composite weight ratio
65/35		55/45		35/65
Sample	Impact energy (Joule)	Sample	Impact energy (Joule)	Sample	Impact energy (Joule)
1	11.7	1	10.3	1	10.8
2	13.6	2	10.8	2	9.6
3	12.4	3	11	3	10.1
Average	12.6	Average	10.7	Average	10.17

Similarly, Figure 6 conveys the relative impact energy resistance capabilities between three different fibers to matrix weight ratios. Among these, the one having 65% fiber and 35% matrix has better strength properties as indicated in material A.

Figure 6. Impact energies of E-Glass/ Polyester composite samples.

3.1. Finite Element Result

First, the 3D model of the composite specimen was modeled using Ansys Acp-pre which is one of the Ansys packages and has various design features that allow modeling the required composite laminate structure by accessing the desired constituents as shown in Figure 7(a).

Figure 7. 3D Model of the composite specimen (a) Zoomed, triangular element of meshes (b) and Load and boundary condition of discretized impact specimen (c)

To determine the numerical result, Ansys explicit dynamics software was used, which is the other element of Ansys packages and is preferred for analysis purposes. To make our analysis more robust and support the software to easily solve for different equations during the analysis, triangular elements of meshes are used as shown in Figure 7(b) and a grid independence test was performed by varying mesh size before analysis, as shown in Table 3. At 0.05 mm mesh size 1420601 number of triangular elements has been obtained, which is capable to produce better results in a short time. After this mesh, the number of elements is almost similar and does not affect the result, but requires a longer execution time. Therefore, for this analysis, all the corresponding values can be used for the mentioned mesh size and the number of elements. The benefit of using these values are minimizing computer processing time during analysis and getting better simulation results in a shorter period.

Table 3. Grid Independence test and mesh information

meshes	mesh size	number of nods	number of element	element quality
				minimum	maximum	average	standard deviation
1	coarse	686	75	0.183	0.95	0.56	0.15
2	medium	829	94	0.36	0.83	0.58	0.0064
3	fine	1585	192	0.59	0.86	0.77	0.0030
4	2.5	2096	260	0.56	0.91	0.85	0.0029
5	2	2743	3.46	0.66	0.96	0.91	0.00304
6	1.8	4136	535	0.78	0.99	0.97	0.00223
7	1.4	5417	708	0.76	1.00	0.98	0.003024
8	1	13,561	2298	0.60	0.95	0.88	0.00213
9	0.5	23,300	4012	0.81	0.99	0.97	0.00168
10	0.1	68,747	13,245	0.67	0.99	0.97	0.00158
11	0.08	3,038,301	699,770	0.63	1	0.99	0.00113
12	0.05	6,056,373	1,420,601	0.66	0.99	0.99	0.00137

As shown in Figure 7, in the free and mesh model of the specimens, the boundary condition was initialized as the bottom areas of the specimens were tightened in the anvil of the Izod impact testing machine as shown in Figure 7(c). Therefore, the specimens are fixed at the lower ends and the impact loads are applied in the notched area of the specimens.

Figures 8, 9, and 10 show the result of equivalent stress, total and directional deformations of E-glass/polyester composite for each variable fiber to matrix ratios using impact loading. This result allows us to recognize the practical application of glass-reinforced composite materials. These maximum stress and displacement values are presented in Table 4.

Figure 8. Equivalent stress (a), Total deformation (b), and Directional deformation (c) of material A.

Figure 9. Equivalent stress (a), Total deformation (b), and Directional deformation (c) of material B.

Figure 10. Equivalent stress (a), Total deformation (b), and Directional deformation (c) of material C.

Table 4. Summary of maximum stress and displacement result

Materials	Striking force (N)	The maximum stress (N/mm^2)	Maximum displacement (mm)
A	30	51.56	1.4
B	30	97.8	1.58
C	30	111.5	3.78

Figure 8 represents the 65/35 fiber-matrix weight ratio, and the red color of the simulation result indicates the maximum values of each parameter. For this content, as shown in Figure 8(a), the maximum equivalent stress is 51.46 Mpa when the impact load is applied over the specimen. The total and directional deformation of this material is also 10 mm and 1.4 mm, respectively, as shown in Figure 8(b & c). This agrees well with the stated fiber matrix weight ratios. However, if the increased deformation of the composite has occurred, high delamination behavior has certainly been shown within the composite (Claus et al., 2020).

Similarly, Figure 9 shows composites having a 55/45 fiber–matrix weight ratio. And 97.79 Mpa stress and 1.58 mm directional deformations are obtained. The main load-bearing element in a composite is a fiber and the load-transfer element is a matrix. when more fiber contents are available in a composite, high strength properties are achieved (Singh et al., 2013). Therefore, for this study, the main load-carrying element is E-glass fiber, and as the fiber content decreased from 65% to 55% the load-bearing capacity of the composite also decreased. And then when matrix content increased to 45%, 97.79 Mpa of stress was transferred to a composite as presented in Figure 9(a). Figure 10 shows 35/65 fiber–matrix contents. The maximum equivalent stress as depicted in Figure 10a) is 111.47 Mpa and 14.5 mm and 3.178 mm total, and directional deformations are obtained respectively as presented in Figure 10(b & c) in the analysis. Since the stress of 111.47 Mpa was transferred from the matrix to the fiber in the composite, this is due to a matrix increasing by 65%. Moreover, the deformation behavior of 35%, 45%, and 65% matrix composition was evaluated. As shown in Figure 10(b & c) with 35% fiber composition, the total and directional deformations are 10 and 1.4 mm respectively. Whereas for 45% of the fiber composition, as shown in Figure 9(b & c), total and directional deformations are 10.092 and 1.588 mm, respectively, and for 65% of the matrix in the composite 14.49 mm total and 3.78 mm directional deformations are determined. This reveals that as the matrix increased from 35% to 65% in a composite, the higher deformation properties resulted and the brittleness of the composite increased. As such, the composite structure was easily delaminated when the load was transferred from the matrix to the fiber. However, this has been improved by increasing the fiber content in the composite and this is the assertion and attribute of E-glass fiber to have better elasticity properties than the matrix in the composite (Patnaik et al., 2012).

The energy summaries of materials A, B, and C are presented in Figures 11, 12, and 13, respectively.

Figure 11. Energy summary of material A.

Figure 12. Energy summary of material B.

Figure 13. Energy summary of material C.

The Figure shows when the impact load hits the specimen, the kinetic energy, and internal energies remain lower. Since the speed of the striker has been decreased due to the impact on the specimen, this triggers the occurrence of lower energy associated with the motion of the striker. However, after impact, the load rebounds at a certain speed, and the kinetic and internal energies are increased. In addition to this, hourglass energy appears in the distorted part of the specimen. It indicates the deformation elements and as the cycle increased, it also increased proportionally. On the other hand, contact energy has occurred between the surface of the striker and its target. This interface energy was generated when the contact force was multiplied by the displacement of the target nodes and it depends on the intensity of the impact force and the change of deformation.

As can be seen from the figures below, the contact energy is lower and steadily increases with increasing time (cycles). This affirms the composite’s uniform resistance to impact penetration through fiber and matrix. As shown in Figure 12, kinetic and internal energy are smaller when the impact load hits the sample. Thus, during the impact, the striker stays attached for a short time and its motion was lowered until the load bounce and increases gradually. Similarly, as shown in Figure 13, the internal and kinetic energies are increased as the striker returns. However, the increase in internal energy is high than the kinetic energy. Thus, kinetic energy is one element of internal energy as such, it should be lower.

4. Conclusion

The E-glass fiber mat as reinforcement and the polyester resin as a matrix with the fiber weight ratio of 65%, 55%, and 35% composite specimens are repaired using hand lay-up techniques. E-glass/polyester impact strength was experimentally studied using an Izod impact testing machine and Ansys explicit dynamics for the numerical analysis. The main findings from the analysis are mentioned as follows:

• The results of this study show that the percentages of fiber determine the load-bearing capacity of the composite and load transformation capabilities are depending on the contents of the matrix. Thus, 65% fiber composite provides maximum impact strength of 12.6 Joule and 51.46 Mpa stress concentration with 1.4 mm deformation.

• The available contents of fiber and matrix have a significant consequence on the properties of the composite. In 55% fiber composite the maximum impact energy absorption was 10.7 Joule with 97.79 Mpa stress and 1.588 mm deformation.

• For 35% E-glass fiber mat composition 10.17 Joule impact energies are achieved and 111.47 Mpa stress and 3.78 mm, deformations are developed on the composite structure and these loads are easily transferred through the matrix to the fiber in the composite while it was loaded.

• The comparative investigation of E-glass/polyester with variable fiber weight composition (65%, 55%, and 35%) results show that the presence of matrix than the fiber in a composite precipitate higher stress concentration and more brittle properties. thus, the composite with 65% of fiber sustains good mechanical properties and it attributed that the desirable properties have been improved by adding more fiber than matrix during composite fabrication.

• Finally, we suggest that the produced E-glass/polyester composite is a very essential material for the fabrication of vehicle structural parts (such as bumpers, roofs, trunk lids, window frames, etc.) due to its better mechanical properties and lightweight as observed from this study.

• Even though our study has an important contribution to the literature, it is not without limitations. This study has not included morphological characterization and other mechanical tests due to the inaccessibility of the apparatus. The upcoming study could focus on these concepts and it would be insight full to analyze the overall characteristics of composite materials.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors received no direct funding for this research.

Notes on contributors

Sisay Asmare

Sisay Asmare is a faculty member of Woldia University, Institute of Technology and Department of Mechanical Engineering, Woldia Ethiopia. The author’s areas of interest are fiber-reinforced polymer matrix characterization, machinability, thermal resistance capability, etc. of polymer composite. In this manuscript, the author found that, the influence of varying weight percentages of E-glass fiber and polyester resin matrix in the impact strength properties of a composite.